ABSTRACT
The Wnt signaling pathway plays key roles in various developmental processes. Wnt5a, which activates the non-canonical pathway, has been shown to be particularly important for axon guidance and outgrowth as well as dendrite morphogenesis. However, the mechanism underlying the regulation of Wnt5a remains unclear. Here, through conditional disruption of Foxg1 in hippocampal progenitors and postmitotic neurons achieved by crossing Foxg1
ABSTRACT
The main lysosomal protease cathepsin D (cathD) is essential for maintaining tissue homeostasis via its degradative function, and its loss leads to ceroid accumulation in the mammalian nervous system, which results in progressive neurodegeneration. Increasing evidence implies non-proteolytic roles of cathD in regulating various biological processes such as apoptosis, cell proliferation, and migration. Along these lines, we here showed that cathD is required for modulating dendritic architecture in the nervous system independent of its traditional degradative function. Upon cathD depletion, class I and class III arborization (da) neurons in Drosophila larvae exhibited aberrant dendritic morphology, including over-branching, aberrant turning, and elongation defects. Re-introduction of wild-type cathD or its proteolytically-inactive mutant dramatically abolished these morphological defects. Moreover, cathD knockdown also led to dendritic defects in the adult mushroom bodies, suggesting that cathD-mediated processes are required in both the peripheral and central nervous systems. Taken together, our results demonstrate a critical role of cathD in shaping dendritic architecture independent of its proteolytic function.
ABSTRACT
Objective: The purpose of the study is to investigate the effects of mobile phone [MP] radiofrequency electromagnetic fields (RF-EMF) exposure for different durations on dendritic morphology and nerve cell damage in CA3 sub region of Hippocampus in Swiss albino mice. Materials &Methods: Total 70 Swiss albino mice of both sexes were used in the study. Animals were divided into 10 groups randomly. Five groups (n=6) were used for assessment of neuronal damage by cresyl violet staining. Another five groups (n=8) were used for assessment of dendritic morphology by Golgi- Cox staining. Groups were divided by exposure duration (15, 30, 45 and 60 minutes/ per day for 30 days); age matched unexposed groups served as controls. Results: Results of the study have shown that there was decrease in the number of viable neurons and dendritic arborization in CA3 sub region of hippocampus in 30, 45 and 60 min exposed groups. Conclusions: Increased neuronal damage and decreased dendritic arborization of hippocampal CA3 neurons was found with increase in exposure duration of MPRF-EMF.
ABSTRACT
The hippocampus is located bilaterally in the medial temporal lobe; within the hippocampus the flow of information is unidirectional. Repeated psychological stress, aging and dementia may leads to the dendritic atrophy in CA1 pyramidal neurons of hippocampus. Accordingly, the present study was designed to investigate the role of aqueous root extract of Glycyrrhiza glabra (Gg) treatment on the dendritic arborization and dendritic intersections of hippocampal CA1 neurons in 3 months old male Wistar albino rats. The aqueous root extract of Glycyrrhiza glabra was administered orally in four different doses (75, 150, 225 and 300 mg/kg) for 2, 4 and 6 weeks duration, respectively. At the end of the spatial memory tests, the rats were sacrificed by deeply anesthetized Pentobarbitone, their brains were removed rapidly and Hippocampal CA1 region studied through Rapid Golgi staining. Hippocampal CA1 neurons were traced using camera lucida, and Quantification of dendritic branching points and dendritic intersections were quantified by using concentric circle method of Sholl. All the doses of aqueous root extract of Gg for 6 weeks showed significantly enhanced dendritic arborization and dendritic intersections however in the dose of 150 and 225 mg/kg/p.o showed a significant (p<0.01) enhancement of dendritic arborization and dendritic intersections along the length of both apical and basal dendrites in hippocampal CA1 pyramidal neurons is comparable to control. However, the rats treated for 2 and 4 weeks did not show any significant change in hippocampal CA1 neuronal dendritic arborization. Thus the constituents present in aqueous root extract of Gg may stimulate the release of neuromodulators or neuronal dendritic growth stimulating factors that alter the activity of neurotransmitters that are involved in learning and memory, which thereby may be useful in management of impaired learning, dementia, Alzheimer’s disease and other neurodegenerative disorders.
ABSTRACT
OBJECTIVE: In the ancient Indian system of medicine, Ayurveda, Bacopa monniera is classified as Medhya rasayana, which includes medicinal plants that rejuvenate intellect and memory. Here, we investigated the effect of a standardized extract of Bacopa monniera on the dendritic morphology of neurons in the basolateral amygdala, a region that is concerned with learning and memory. METHODS: The present study was conducted on 2¹/2-month-old Wistar rats. The rats were divided into 2-, 4- and 6-week treatment groups. Rats in each of these groups were further divided into 20 mg/kg, 40 mg/kg and 80 mg/kg dose groups (n = 8 for each dose). After the treatment period, treated rats and age-matched control rats were subjected to spatial learning (T-maze) and passive avoidance tests. Subsequently, these rats were killed by decapitation, the brains were removed, and the amygdaloid neurons were impregnated with silver nitrate (Golgi staining). Basolateral amygdaloid neurons were traced using camera lucida, and dendritic branching points (a measure of dendritic arborization) and dendritic intersections (a measure of dendritic length) were quantified. These data were compared with the data from the age-matched control rats. RESULTS: The results showed an improvement in spatial learning performance and enhanced memory retention in rats treated with Bacopa monniera extract. Furthermore, a significant increase in dendritic length and the number of dendritic branching points was observed along the length of the dendrites of the basolateral amygdaloid neurons of rats treated with 40 mg/kg and 80 mg/kg of Bacopa monniera (BM) for longer periods of time (i.e., 4 and 6 weeks). CONCLUSION: We conclude that constituents present in Bacopa monniera extract have neuronal dendritic growth-stimulating properties.