|
| |
 |
|
| ORIGINAL ARTICLE |
|
| Year : 2023 | Volume
: 11
| Issue : 1 | Page : 52-59 |
|
The possible effects of vitamin D3 on AlCl3-Induced histological and morphometric alterations of adult male albino rat hippocampus
Jana Kamel Bashraheel1, Zienab A Alrefaie2, Hossam Eldin Ahmed Awad Hammad3, Soad Shaker Ali4
1 Department of Physiology, Faculty of Medicine, King Abdulaziz University; Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
2 Department of Physiology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia; Department of Physiology, Faculty of Medicine, Cairo University, Cairo, Egypt
3 Department of Physiology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia, Saudi Arabia
4 Faculty of Medicine, King Abdulaziz University, Jeddah Saudi Arabia; Faculty of Medicine, Assuit University, Egypt; Member of YAJ, Chair, Center of Excellence of Prophet Medicine Applications, KAU, Jeddah Saudi Arabia
| Date of Submission | 26-Apr-2021 |
| Date of Decision | 02-Jun-2021 |
| Date of Acceptance | 05-Jul-2021 |
| Date of Web Publication | 06-Nov-2021 |
Correspondence Address:
Ms. Jana Kamel Bashraheel
Department of Physiology, Faculty of Medicine, King Abdulaziz University, Jeddah
Saudi Arabia
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/jmau.jmau_42_21
Context: Alzheimer's disease (AD) is a challenging neurodegenerative disease, and Vitamin D was proved to have neuroprotective effects. Aim: This study was conducted to evaluate the potential neuroprotective effects of Vitamin D3 supplementation on AlCl3-induced AD rat model in different hippocampal subregions (CA1, CA2, and CA3). It also aimed to compare the protective effects of protective versus therapeutic effects of Vitamin D3 regiments on the number of degenerated neurons and the neuronal layer thickness. Materials and Methods: Twenty-four adult male Albino Wister rats were sorted into GI: control; GII: AlCl3-AD model (100 mg/kg) orally for 42 days; GIII: Rats were co-treated with AlCl3 (as GII) and Vitamin D3 (400 IU/kg/day) orally for 42 days; GIV: Rats were treated with AlCl3 for 42 days then with Vitamin D3 for further 2 weeks. Sagittal sections (5 μ) from paraffin-processed brains previously fixed in 10% neutral-buffered formalin were stained with hematoxylin and eosin to evaluate the thickness and number of degenerated neurons in the hippocampal CA1, CA2, and CA3 subregions. Statistical Analysis: The results of this study were expressed as mean ± standard deviation and analyzed by using IBM SPSS Statistics for Windows, version 23 (IBM SPSS, IBM Corp., Armonk, N.Y., USA). P < 0.05 was considered statistically significant. Results: Vitamin D3 supplementations modulated the degenerative changes observed in the hippocampus of AD rat model. In all hippocampal subregions, the thickness was higher in rats treated with Vitamin D3 after the AD induction than rats treated with Vitamin D3 during AD induction. However, this increase was only significant in CA2. Comparison of the number of degenerated neurons between both groups treated with Vitamin D3 revealed that in CA1, the number of degenerated neurons did not statistically differ between the two groups. However, it was insignificantly lower in CA2 in rats treated with Vitamin D3 after the AD induction, and in CA3, it was insignificantly lower in rats treated with Vitamin D3 during the AD induction. Conclusions: Vitamin D3 was found to be effective in ameliorating histological and morphometric alterations in AlCl3-induced AD in rat model and could be proposed as both preventive and therapeutic supplements in high-risk AD patients.
Keywords: Alzheimer's disease, rat hippocampal subregions and histological alterations, Vitamin D3 supplementations
How to cite this article:
Bashraheel JK, Alrefaie ZA, Hammad HE, Ali SS. The possible effects of vitamin D3 on AlCl3-Induced histological and morphometric alterations of adult male albino rat hippocampus. J Microsc Ultrastruct 2023;11:52-9 |
How to cite this URL:
Bashraheel JK, Alrefaie ZA, Hammad HE, Ali SS. The possible effects of vitamin D3 on AlCl3-Induced histological and morphometric alterations of adult male albino rat hippocampus. J Microsc Ultrastruct [serial online] 2023 [cited 2023 Mar 20];11:52-9. Available from: https://www.jmau.org/text.asp?2023/11/1/52/329881 |
| Introduction | |  |
Alzheimer's disease (AD) is a worldwide epidemic that is a major cause of morbidity and higher death rate in the elderly population. The global number of AD patients is estimated by the World Health Organization and Alzheimer's Association to be more than 35 million individuals. Numerous national and international attempts were made to discover successful methods to either protect against or slow AD progression, but still no cure exists for AD.[1]
The hippocampus is a region of the brain that is crucial for the creation and storage of semantic declarative and episodic memories. Its synaptic plasticity aids in the process of memory consolidation and long-term memory storage. Thus, this area is vital for learning as well as the new memories acquisition and retention.[2] In AD's early stages, the neurogenesis of the hippocampus is impaired and is believed to aid in the early decline of cognition.[3]
Vitamin D is a member of vitamins that are soluble in fat.[4] It has several biological effects including skeletal and nonskeletal functions.[5] Sources of Vitamin D include diet, sunlight, and medicinal supplementation,[6] and its deficiency is revealed by accumulating evidence to be a global health problem.[7] Furthermore, Vitamin D is suggested by mounting evidence to have positive effects on the risk of the development of neurodegenerative diseases,[8] including AD.[9]
Vitamin D acts on tissues and cells that possess its receptor. Vitamin D receptors (VDRs) are expressed in several brain areas in both humans and animals, including the hypothalamus, the thalamus, and the hippocampus,[10] where its expression is among the highest areas.[11]
Vitamin D and its metabolites have the ability of crossing the blood–brain barrier (BBB). VDRs were also reported to be expressed in glial and neuronal cells, which could indicate a possible influence of Vitamin D on the functions of the central nervous system.[12]
Moreover, several reported biological actions of Vitamin D in the brain including modification of the growth and differentiation of neurites as well as modulation of synaptic plasticity and neurotransmission.[13]
Aim
This study was conducted to evaluate the potential neuroprotective effects of Vitamin D3 supplementation on AlCl3-induced AD rat model in different hippocampal subregions (CA1, CA2, and CA3). It also aimed to compare the protective versus therapeutic effects of Vitamin D3 regiments on the number of degenerated neurons and the neuronal layer thickness.
| Materials and Methods | | |
Animals
Twenty-four adult male Albino Wistar rats (200–225 g) were used in this study. Ethical approval with the reference number (774-19) was granted from the Ethical Committee, Faculty of Medicine, at King Abdulaziz University. All international guidelines of animal care were followed. Rats were kept for 1 week at optimum laboratory conditions (12-h light/dark cycle, temperature [23°C ± 3°C] with free access to food and water).
Animal grouping and study plan
A total of 24 rats were randomly divided into four groups, with six rats in each group as follows:
- Group I: Control group received only standard rat pellets and water
- Group II: AD group, where rats received AlCl3 orally (100 mg/kg bw) for 42 days[14]
- Group III: Preventive group, rats received AlCl3 in the same dose and manner of Group II and also received Vitamin D3 at the same time (400 IU/kg/day) orally for 42 days[15]
- Group IV: Therapeutic group, rats received AlCl3 in the same dose and manner of Group II and also orally received Vitamin D3 in the same dose of Group III but after the end of establishment of AD induction and for a time period of 2 weeks.
Rat sacrifice and brain samples collection
Animals were euthanized by gentle cervical dislocation, and their heads were immediately placed on ice and the brain was dissected out, washed with ice-cold saline, and then cut in sagittal plane for further processing.[16]
Histological examination
For histological examination, 10% neutral-buffered formalin was used to fix dissected brains for 24 h followed by dehydration with serial grades of 99.7%–100% ethanol. Xylene was then used to clear the samples; then, they were impregnated in paraffin at 56°C for 24 h followed by paraffin blocking in hard paraffin. Four-micron sections were stained with hematoxylin and eosin (H and E) stain.[17] The Olympus, BX51TF, Brightfield Microscope connected to a digital camera was used to examine and photograph the slides.
Morphometric study
The thickness of hippocampal subregions (CA1, CA2 and CA3) as well as the number of degenerated dark stained cells were estimated in three non-overlapping visual fields (x1000) in four random sections from each rat using Image Pro Plus software (Media Cybernetics, Silver Spring, USA, version 4.5) connected to a Brightfield Microscope, (Olympus Corporation, Tokyo, Japan, BX51TF) and a digital camera, (Olympus Corporation, Tokyo, Japan, DP-70), [Figure 1]. | Figure 1: Photomicrographs from rat hippocampal regions to show low power (×40) to demonstrate different subhippocampal regions (CA1, CA2, and CA3) and dentate gyrus (DG); scale bar (500 μ). Further, the software methodology of measuring neuronal layer thickness (at ×1000). Scale bar = 20 μ
Click here to view |
Data analysis
The results of this study were expressed as mean ± standard deviation (SD) and analyzed by IBM SPSS Statistics for Windows, version 23 (IBM SPSS, IBM Corp., Armonk, N.Y., USA). P < 0.05 was considered statistically significant. Data were expressed as mean ± SD. Significance was made using one-way ANOVA test followed by Turkey's test for multiple comparison between groups. For data that are not normally distributed, data were expressed as mean ± SD and mode (interquartile range). Significance between groups was made using Mann–Whitney test.
| Results | | |
Assessment of histological changes in rat hippocampal subregions (CA1, CA2 and CA3) in all studied groups
In the present study, H and E-stained paraffin sections of the hippocampal regions were used to evaluate the role of Vitamin D3 as both preventive and therapeutic supplements against AlCl3-induced alteration (AD) in the rat in different hippocampal subregions. [Figure 2], [Figure 3], [Figure 4] demonstrated the low power of rat hippocampus with labeled CA1, CA2, and CA3 subregions. Rats treated with AlCl3 (B), showed marked degenerative (apoptotic) changes in the form of neuronal shrinkage, shape deformity and dark-stained cytoplasm that masked the degenerated ill-defined nuclei when compared to the viable neurons with their active vesicular nuclei in the control group (A). Furthermore, the presence of both extra and intracellular tangles (fine acidophilic filamentous deposition that is characteristic to Alzheimer's disease) besides to increased glial cells were also observed in group (B). The presence of both extra and intracellular tangles (as fine acidophilic filamentous deposition) which is characteristic to AD lesions besides increasing glial cells was also observed in AD group (B). | Figure 2: Paraffin sections from CA1 subregion of rat hippocampus stained by hematoxylin and eosin and photographed at ×600 to show: (a) Normal control showing normal layers of viable pyramidal cells. They possess large euchromatic active nuclei with prominent nucleoli (black arrow). Few sporadic dark stained degenerated (apoptotic) cells could be seen (white arrows). Glial cells with its small dark nuclei are infrequent and could be seen among the neurons (dotted arrow). (b) Alzheimer's disease group (AlCl3-Alzheimer model): Pyramidal cells looked deformed with dark stained cytoplasm (white arrow) masking the degenerated pyknotic nuclei. The nuclei of the rest of neurons looked abnormal and showed vacuolated or reticulated nucleoplasm (black arrow). Glia cells showed smaller nuclei (dotted arrow). (c) Preventive group (AlCl3 + Vitamin D3) showing decrease in the number of degenerated cells (white arrows) compared to Alzheimer's disease group. Viable neuronal cells showed normal vesicular active nuclei (black arrow). Glia cells are identified by their small nuclei (dotted arrow). (d) Therapeutic (AlCl3 then Vitamin D3) showing also decrease in the number of degenerated cells (white arrows). Viable cells showed cytoplasm and nuclei (black arrow) which looked more similar to control group. Glia cells showed smaller nuclei (dotted arrows)
Click here to view |
 | Figure 3: Paraffin sections from CA2 subregion of rat hippocampus stained by hematoxylin and eosin and photographed at ×600 to show: (a) Normal control showing viable pyramidal cells having large vesicular (euchromatic) active nuclei with prominent nucleoli (black arrows). Sporadic dark stained degenerated (apoptotic) cell could be seen (white arrow). Glial cells with its small dark nuclei are infrequently observed (dotted arrows), white mater (white star) is homogenously stained. (b) Alzheimer's disease group (AlCl3-Alzheimer model) showing marked disorganization of neuronal cell layers. Pyramidal cells looked deformed with dark stained cytoplasm (white arrows) masking the degenerated pyknotic nuclei. White matter (white star) among the cells looked rarified and reticulated with deposition of filamentous material known as tangles (black stars). Nuclei of glial cells could also be seen among neurons (dotted arrows). (c) Preventive group (AlCl3 + Vitamin D3) showing slight disorganization of neuronal layers. Most neurons looked viable with vesicular (euchromatic) nuclei and well-defined nucleoli (black arrows) indicating activity. No degenerated cells could be observed but some cells looked elongated or abnormal in shape with darker stained cytoplasm (white arrow) compared to normal neurons. White mater looked normal (white star). Glia cells showed smaller nuclei (dotted arrows). (d) Therapeutic group (AlCl3 then Vitamin D3) showing nearly normal neuronal organization. Neuronal cytoplasm and nuclei (black arrows) looked similar to control group. Glial cells also are infrequent (dotted arrow). Sporadic few degenerated cells could be seen (white arrow), white mater is homogenously stained and looked normal (white star)
Click here to view |
 | Figure 4: Paraffin sections from at CA3 subregion of rat hippocampus stained by hematoxylin and eosin and photographed at × 600 showed: (a) Normal control with viable pyramidal cells having large euchromatic active nuclei with prominent nucleoli (black arrow). One sporadic dark stained degenerated (apoptotic) cell could be seen (white arrow). Glial cells with its small dark nuclei are infrequent and could be seen among neurons (dotted arrows). White mater showed normal homogenous acidophilic staining intensity (white star). (b) Alzheimer's disease group (AlCl3-Alzheimer model): Pyramidal cells looked deformed with dark stained cytoplasm (white arrow) masking the degenerated pyknotic nuclei. The white matter beneath the cells looked rarified and reticulated (white star) with deposition of filamentous material known as tangles (black stars) among the cells. Nuclei of glial cells could be seen among the neurons (dotted arrows). (c) Preventive group (AlCl3 + Vitamin D3): The number of degenerated cells (white arrow) is less compared to Alzheimer's disease group. White mater (white star) looked also less affected compared to nontreated Alzheimer's disease group. Viable neuronal cells showed normal vesicular active nuclei (black arrow). Glial cells could be identified by their smaller nuclei (dotted arrow). (d) Therapeutic group (AlCl3 then Vitamin D3): There is also apparent decrease in the number of degenerated cells (white arrow). Viable cells showed cytoplasm and nuclei (black arrow) which looked more similar to control group. White matter (white star) and glial cells (dotted arrow) could be observed
Click here to view |
Histological studies also demonstrated the role of Vitamin D3 as a preventive supplement (C) in amelioration of the toxic insult of AlCl3 on hippocampal neurons or as a therapeutic supplement (D) when the toxic AlCl3 was stopped and replaced by Vitamin D3 where most neurons and glial cell population looked nearly normal and similar to those of the control group.
Assessment of changes in the thickness of hippocampal subregions (CA1, CA2, and CA3) in all studied groups
The morphometric changes in the thickness of hippocampal subregions in the all studied groups are demonstrated in [Table 1]. | Table 1: Comparison of thickness of hippocampus at different areas in different studied groups
Click here to view |
The thickness of CA1 and CA3 in AD (AlCl3-treated) rats was shown to be nonsignificantly reduced compared to control rats. However, CA2 thickness in AD rats was found to be significantly decreased compared to normal rats. On the contrary, CA1 and CA3 thickness was shown to be insignificantly high in both groups treated with Vitamin D3 compared to normal rats and significantly high compared to AD rats.
However, the thickness of CA2 subregion in rats treated with Vitamin D3 during the AD induction was significantly increased in comparison to both normal and AD rats. Moreover, the thickness of CA2 in rats treated with Vitamin D3 after the AD induction (was insignificantly increased compared to normal rats and significantly increased compared to AD rats.
Interestingly, treatment with Vitamin D3 after the AD induction insignificantly increased CA1 and CA3 thickness in comparison to Vitamin D3 treatment during the AD induction. Furthermore, in CA2, treatment with Vitamin D3 after the AD induction significantly increased the thickness in comparison to Vitamin D3 treatment during the induction of AD.
Assessment of the number of degenerated neurons in the hippocampal subregions (CA1, CA2, and CA3) in all studied groups
The number of degenerated neurons in the hippocampal subregions (CA1, CA2, and CA3) in the studied groups is demonstrated in [Table 2]. | Table 2: Comparison of number of degenerated cells of hippocampus at different areas in different studied groups
Click here to view |
It was observed that in AD (AlCl3-treated) rat group, the number of degenerated deeply stained neurons in the CA1 subregion was insignificantly high compared to the normal group.
It was also demonstrated that the number of such degenerated neurons was significantly higher in CA2 and CA3 subregions in the AD (AlCl3-treated) rat group compared to matched regions of control hippocampus.
Moreover, rats treated with Vitamin D3 during the AD induction demonstrated an insignificantly higher number of degenerated neurons than normal rats in all three hippocampal subregions. Treatment with Vitamin D3 during the AD induction insignificantly lowered degenerated neuron number in CA1 compared to AD rats and also significantly reduced the number of these cells in both CA2 and CA3 compared to AD rats.
Furthermore, rats treated with Vitamin D3 post their AD induction demonstrated an insignificantly higher number of degenerated neurons in the CA1 and CA3 compared to the normal rats. However, compared to AD rats, rats treated with Vitamin D3 post their AD induction demonstrated an insignificantly less degenerated neurons number in CA1 and a significantly low number of degenerated neurons in CA2 and CA3.
Moreover, in CA1, no statistical difference was found in the number of degenerated neurons between the two groups treated with Vitamin D3. However, in CA2, treatment with Vitamin D3 after AD induction caused an insignificantly lower number of degenerated neurons than treatment with Vitamin D3 during the induction of AD. On the contrary, in CA3, the number of degenerated cells was insignificantly lower in rats treated with Vitamin D3 during the AD induction (preventive group) than rats treated with Vitamin D3 after the AD induction.
| Discussion | | |
Recent literature focused the attention on the implication of Vitamin D3 deficiency as a risk factor of AD.[18] The neuroprotective effects of Vitamin D3 and its capability in preventing the oxidative stress consequences were also reviewed by Kalueff et al. and Panza et al.[19],[20]
The present study was designed to evaluate the possible protective as well as therapeutic efficacy of Vitamin D3 on the hippocampus of the AD model in rats induced by AlCl3.
Histological examination combined by quantitative morphometric studies was used to evaluate the efficacy of Vitamin D3 supplementation to ameliorate the alteration in rat hippocampal subregions (CA1, CA2, and CA3) that result from AlCl3-induced insult. The hippocampus of the rat is composed of several regions and includes the hippocampus proper (with its three subregions: CA1, CA2, and CA3), the dentate gyrus, and the subiculum.[21]
AlCl3 is an identified neurotoxin that has been linked to AD since it leads to neuronal inflammation, worsens the oxidative injury of the brain, and triggers the deposition of Aβ, which impairs the working memory.[22] AlCl3 was also reported to possess the ability of crossing the BBB and the accumulation in many brain regions.[23]
In the present study, H and E sections demonstrated the presence of marked histological alterations in all hippocampal subregions, especially in CA2 in the rats treated with AlCl3. Histological changes included neuronal shape deformity, shrinkage, and dark cytoplasmic staining with degenerated pyknotic nuclei. The present data are in consistence with the results reported by Zhao et al.,[24] in which the neurons in the hippocampi of rats treated with intraperitoneal AlCl3 (100 mg/kg/bw) for 60 days were shrunken and had hyperchromatic nuclei.
The results are also consistent with the study of Haider et al.,[23] who reported that neuronal cytoplasm in the hippocampi of rats treated via intraperitoneal route with AlCl3 (150 mg/kg/bw) and D-galactose (300 mg/kg/bw) for 1 week looked darkly stained. The present results also go in hand with that of Khalaf et al.,[25] who reported the presence of several apoptotic bodies in the hippocampi of Sprague–Dawley rats treated with AlCl3 (100 mg/kg/bw) orally for 42 days.
The results of the current study are also similar to those previously reported by Aboelwafa et al.,[22] who demonstrated marked alterations in the hippocampi of rats treated with intraperitoneal AlCl3 (17 mg/kg/bw) for 15 days.
The presence of acidophilic extracellular neurofibrillary tangles (NFTs) among dark-stained degenerated neurons could be explained in view of the study done by Haider et al.,[23] who reported that changes in the morphology of the neurons are the most common reported characteristic of AlCl3 toxicity which causes functional and structural alterations in cytoskeletal proteins, the buildup of hyperphosphorylated proteins that lead to NFT formation, and the breaking of axons and dendritic system with subsequent neurodegeneration.
In the present study, morphometric measurements were done to provide quantitative evidence for alterations in hippocampus regions. Furthermore, this study demonstrated that, in AD (AlCl3-treated) rats, the thickness of hippocampal CA1, CA2, and CA3 subregions was generally decreased compared to the normal rats. However, this decrease was only significant in CA2 subregion. These findings are consistent with that of Harakeh et al.,[26] in which the mean thickness of CA3 subfield was reported to be reduced in Sprague–Dawley rats orally treated with (17 mg/kg/bw) AlCl3 for 28 days to induce AD.
These results are also consistent with what was reported by Al-Neklawy,[27] in which the thickness of CA1 and CA2 subregions was insignificantly reduced and significantly reduced, respectively, in male albino Wistar rats treated with (80 mg/kg/bw) orally chloroquine, for 2 weeks, in comparison to normal. However, the present study disagrees with Al-Neklawy[27] in regard to CA3 thickness, in which it was reported to be significantly decreased, whereas it was found in the present study to be insignificantly decreased. The difference could be attributed to the substance used for AD induction and the duration of induction.
Moreover, the current study agrees with the study of Aboelwafa et al.,[22] where the thickness of CA1 was reported to be reduced in male Wistar rats treated with (17 mg) intraperitoneal AlCl3 for 15 days. However, their study reported an insignificant reduction in CA2 thickness, whereas herein it was found to be significantly reduced. This could be attributed to the different durations and doses of AlCl3 treatment.
The thickness of CA1 and CA3 subregions was insignificantly increased by both treatment methods of Vitamin D3 in comparison to normal. In CA2, however, treatment with Vitamin D3 during the AD induction (preventive group) significantly increased the thickness compared to normal. Moreover, treatment with Vitamin D3 after the AD induction (therapeutic group) insignificantly increased the thickness of CA2 compared to normal.
It is noteworthy that treatment with Vitamin D3 after the AD induction increased the thickness of all three hippocampal subregions in comparison to treatment with Vitamin D3 during the AD induction. However, this increase only reached significance in CA2.
Neurogenesis impairment is well known to be linked to aging processes and development of AD in mammalian species.[28] Demars et al.[28] also reported that impaired neurogenesis in hippocampal region is early evidence of AD in transgenic mice.
In the present study, counting the number of degenerated (apoptotic) neurons was used to evaluate the neurotoxic degenerative effects of AlCl3 and the possible preventive or therapeutic role of Vitamin D3 against this effect. AlCl3 administration was found to result in a significant increase in the number of dark-stained degenerated neurons in CA2 and CA3 in comparison to normal. Their number was also increased in CA1 in comparison to normal, but it did not reach significance. No or few viable neurons could be seen in most regions.
The results of this study are consistent with the one reported by Auti and Kulkarni,[29] in which the induction of AD in male Albino Wistar rats, with AlCl3 (100 mg/kg, orally), for 42 days resulted in neurodegeneration in their hippocampi neurons.
These results are also consistent with the results of Chiroma et al.,[30] in which the pyramidal cells of all three hippocampus areas were shown to be markedly degenerated in male Albino Wistar rats treated with AlCl3 (100 mg/kg, p.o.) and D-galactose for 10 weeks.
Ravi et al.[31] also reported neurodegenerative alterations in CA1 and CA3 subareas of male Albino Wistar rats treated with AlCl3 (300 mg/kg, p.o.), for 60 days.
When AlCl3 enters the brain, it affects slow and fast axonal transport, causes structural abnormalities, and inhibits long-term potentiation, thereby causing neurodegeneration. Other AlCl3 effects include the depletion of the brain's cell number as clarified by Chiroma et al.[30] AlCl3 also fastens the process of lipid peroxidation and enhances the production of free radicals, which in turn causes severe neurotoxicity.[22]
AlCl3 was also reported to result in AD-like symptoms in animals as it led to depletion of neuronal elements in the hippocampal region. The neurotoxic effect of AlCl3 was reported to be via enhancing formation of free radicals with subsequent lipid peroxidation and neuronal degeneration.[32]
On the other hand, when the two groups treated with Vitamin D3 (preventive and therapeutic) were compared with the AD model, it was found that both procedures of Vitamin D3 treatment significantly decreased the number of degenerated neurons in CA2 and CA3. However, this decrease was not significant in CA1.
Nonetheless, in comparison to normal, the number of degenerated cells in Vitamin D3 preventive and therapeutic groups was insignificantly higher in CA1 and CA3 and significantly lower in CA2.
Antioxidant vitamins including Vitamin D are considered to exert potent neuroprotective effect,[33] and Vitamin D deficiency, especially in elderly people, is implicated in AD development and cognitive impairment.[34] In experimental animals, Vitamin D was reported to improve cognition via the stimulation and improvement of neurogenesis.[3]
Nonetheless, compared to normal rats, the number of degenerated cells in Vitamin D3 preventive and therapeutic groups was insignificantly higher in CA1 and CA3.
Furthermore, in CA1, no statistical difference was found in the number of degenerated neurons between the two groups treated with Vitamin D3. However, in CA2, the number of degenerated neurons was insignificantly lowered by treatment with Vitamin D3 post the AD induction in comparison to treatment with Vitamin D3 during the AD induction. On the contrary, the number of degenerated neurons in CA3 was insignificantly reduced by Vitamin D3 treatment during the AD induction in comparison to Vitamin D3 treatment after the establishment of AD.
| Conclusions | | |
Histological examination combined with morphometric study of hippocampal subregions thickness and number of degenerated neurons provided an evidence for AlCl3 neurotoxic degenerative effects that simulate what occurs in AD disease in human. Such changes were found to be much ameliorated with Vitamin D3 supplementation given as both protective during the induction of AD rat model or as therapeutic effects after establishment of the model. The study provided evidence that may support the suggestion of carrying more researches to clarify the exact underlying mechanism and optimum doses for Vitamin D supplementation and design plans for clinical trials with AD patients.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Tarawneh R. Biomarkers: Our path towards a cure for Alzheimer disease. Biomark Insights 2020;15:1177271920976367.  |
| 2. | Avchalumov Y, Mandyam CD. Plasticity in the hippocampus, neurogenesis and drugs of abuse. Brain Sci 2021;11:404. |
| 3. | Morello M, Landel V, Lacassagne E, Baranger K, Annweiler C, Féron F, et al. Vitamin D improves neurogenesis and cognition in a mouse model of Alzheimer's disease. Mol Neurobiol 2018;55:6463-79. |
| 4. | Aguilar-Shea AL. Vitamin D, the natural way. Clin Nutr ESPEN 2021;41:10-2. |
| 5. | Kumar R, Rathi H, Haq A, Wimalawansa SJ, Sharma A. Putative roles of vitamin D in modulating immune response and immunopathology associated with COVID-19. Virus Res 2021;292:198235. |
| 6. | Charoenngam N, Holick MF. Immunologic effects of vitamin D on human health and disease. Nutrients 2020;12:E2097. |
| 7. | Szymczak-Pajor I, Drzewoski J, Śliwińska A. The molecular mechanisms by which Vitamin D prevents insulin resistance and associated disorders. Int J Mol Sci 2020;21:E6644. |
| 8. | Maretzke F, Bechthold A, Egert S, Ernst JB, Melo van Lent D, Pilz S, et al. Role of Vitamin D in preventing and treating selected extraskeletal diseases – An umbrella review. Nutrients 2020;12:E969. |
| 9. | Mokry LE, Ross S, Morris JA, Manousaki D, Forgetta V, Richards JB. Genetically decreased Vitamin D and risk of Alzheimer disease. Neurology 2016;87:2567-74. |
| 10. | Uberti F, Morsanuto V, Bardelli C, Molinari C. Protective effects of 1α,25-Dihydroxyvitamin D3 on cultured neural cells exposed to catalytic iron. Physiol Rep 2016;4:e12769. |
| 11. | Moretti R, Morelli ME, Caruso P. Vitamin D in neurological diseases: A rationale for a pathogenic impact. Int J Mol Sci 2018;19:E2245. |
| 12. | Lauer AA, Janitschke D, Hartmann T, Grimm HS, Grimm HOW. The Effects of Vitamin D Deficiency on Neurodegenerative Diseases, in Vitamin D Deficiency, J. Fedotova, Editor, intechopen: United Kingdom. 2019. 1:p125-53. |
| 13. | Banerjee A, Khemka VK, Ganguly A, Roy D, Ganguly U, Chakrabarti S. Vitamin D and Alzheimer's disease: Neurocognition to therapeutics. Int J Alzheimers Dis 2015;2015:192747. |
| 14. | Prema A, Thenmozhi AJ, Manivasagam T, Essa MM, Akbar MD, Akbar M. Fenugreek seed powder nullified aluminium chloride induced memory loss, biochemical changes, Aβ burden and apoptosis via regulating Akt/GSK3β signaling pathway. PLoS One 2016;11:e0165955. |
| 15. | Castillo EC, Hernandez-Cueto MA, Vega-Lopez MA, Lavalle C, Kouri JB, Ortiz-Navarrete V. Effects of Vitamin D supplementation during the induction and progression of osteoarthritis in a rat model. Evid Based Complement Alternat Med 2012;2012:156563. |
| 16. | Hagihara H, Toyama K, Yamasaki N, Miyakawa T. Dissection of hippocampal dentate gyrus from adult mouse. J Vis Exp 2009: p. e15431543. |
| 17. | Ahmed H. Modeling stages mimic Alzheimer's disease induced by different doses of aluminum in rats: Focus on progression of the disease in response to time. J Alzheimers Parkinsonism Dement 2016;1:1-11. |
| 18. | Littlejohns TJ, Henley WE, Lang IA, Annweiler C, Beauchet O, Chaves PH, et al. Vitamin D and the risk of dementia and Alzheimer disease. Neurology 2014;83:920-8. |
| 19. | Panza F, La Montagna M, Lampignano L, Zupo R, Bortone I, Castellana F, et al. Vitamin D in the development and progression of Alzheimer's disease: Implications for clinical management. Expert Rev Neurother 2021;21:287-301. |
| 20. | Kalueff AV, Eremin KO, Tuohimaa P. Mechanisms of neuroprotective action of vitamin D(3). Biochemistry (Mosc) 2004;69:738-41. |
| 21. | Kamsu JM, Constans JM, Lamberton F, Courtheoux P, Denise P, Philoxene B, et al. Structural layers of ex vivo rat hippocampus at 7T MRI. PLoS One 2013;8:e76135. |
| 22. | Aboelwafa HR, El-Kott AF, Abd-Ella EM, Yousef HN. The possible neuroprotective effect of silymarin against aluminum chloride-prompted Alzheimer's-like disease in rats. Brain Sci 2020;10:E628. |
| 23. | Haider S, Liaquat L, Ahmad S, Batool Z, Siddiqui RA, Tabassum S, et al. Naringenin protects AlCl3/D-galactose induced neurotoxicity in rat model of AD via attenuation of acetylcholinesterase levels and inhibition of oxidative stress. PLoS One 2020;15:e0227631. |
| 24. | Zhao Y, Dang M, Zhang W, Lei Y, Ramesh T, Veeraraghavan VP, et al. Neuroprotective effects of Syringic acid against aluminium chloride induced oxidative stress mediated neuroinflammation in rat model of Alzheimer's disease. J Funct Foods 2020;71:104009. |
| 25. | Khalaf NE, El Banna FM, Youssef MY, Mosaad YM, Daba MY, Ashour RH. Clopidogrel combats neuroinflammation and enhances learning behavior and memory in a rat model of Alzheimer's disease. Pharmacol Biochem Behav 2020;195:172956. |
| 26. | Harakeh S, Ramadan W, Al Muhayawi M, Al Jaouni S, Mousa S and Hakeem K. Pomegranate peel extract lessens histopathologic changes and restores antioxidant homeostasis in the hippocampus of rats with aluminium chloride induced Alzheimer's disease. Asian Pac J Trop Med 2020;13:456-63. [Full text] |
| 27. | Al-Neklawy AF. Does oral chloroquine affect the hippocampus in rats? A clue to chloroquine induced neuropsychiatric adverse effects. Ain Shams Med J 2020;71:59-79. |
| 28. | Demars M, Hu YS, Gadadhar A, Lazarov O. Impaired neurogenesis is an early event in the etiology of familial Alzheimer's disease in transgenic mice. J Neurosci Res 2010;88:2103-17. |
| 29. | Auti ST, Kulkarni YA. Neuroprotective effect of cardamom oil against aluminum induced neurotoxicity in rats. Front Neurol 2019;10:399. |
| 30. | Chiroma SM, Mohd Moklas MA, Mat Taib CN, Baharuldin MT, Amon Z. d-galactose and aluminium chloride induced rat model with cognitive impairments. Biomed Pharmacother 2018;103:1602-8. |
| 31. | Ravi SK, Ramesh BN, Mundugaru R, Vincent B. Multiple pharmacological activities of Caesalpinia crista against aluminium-induced neurodegeneration in rats: Relevance for Alzheimer's disease. Environ Toxicol Pharmacol 2018;58:202-11. |
| 32. | Zhang W, Hua H, Guo Y, Cheng Y, Pi F, Yao W, et al. Torularhodin from Sporidiobolus pararoseus attenuates d-galactose/AlCl 3-induced cognitive impairment, oxidative stress, and neuroinflammation via the Nrf2/NF-κB pathway. J Agric Food Chem 2020;68:6604-14. |
| 33. | Lee KH, Cha M, Lee BH. Neuroprotective effect of antioxidants in the brain. Int J Mol Sci 2020;21:E7152. |
| 34. | Mohajeri MH, Troesch B, Weber P. Inadequate supply of vitamins and DHA in the elderly: Implications for brain aging and Alzheimer-type dementia. Nutrition 2015;31:261-75. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]
|
Search Pubmed for