Neuroscience
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With the exception of parturition and lactation, male California deer mice (Peromyscus californicus) exhibit the same parental responses toward offspring as conspecific females. A closely related species, Peromyscus maniculatus, however, rarely exhibits paternal responses. In the current study, a comparative species approach was used to assess paternal responses in both Peromyscus species with varying levels of paternal experience (biological fathers, pup-exposed virgins, and pup-naïve virgins). ⋯ Finally, fos-ir was increased in the medial preoptic area, involved in the maintenance of maternal behavior, in the biological fathers of both species. Thus, although biological predispositions toward pup-directed behaviors were observed in P. californicus males, evidence of a few shifts toward the paternal neural activation profile was apparent in P. maniculatus males. Specifically, modifications in fear responses and social processing may represent the cornerstones of the gradual shift from social tentativeness to social attentiveness in the presence of pups.
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The capability to integrate into degenerative environment, release neurotrophic cytokines, contrast oxidative stress and an inherent differentiation potential towards siteappropriate phenotypes are considered crucial for the use of stem cells in tissue repair and regeneration. Naïve human chorial villi- (hCVCs) and amniotic fluid- (hAFCs) derived cells, whose properties and potentiality have not been extensively investigated, may represent two novel foetal cell sources for stem cell therapy. We previously described that long-term transplantation of hAFCs in the lateral ventricles of wobbler and healthy mice was feasible and safe. ⋯ Both cell types express several specific neural stem/progenitor markers, such as nestin and connexin 43, and release significant amounts of brain-derived neurotrophic factor, as well as vascular endothelial growth factor. hCVC and hAFC populations comprise several interesting cell lineages, including mesenchymal stem cells (MSCs) and cells with neural-like phenotypes. Moreover, although CMs obtained from both cell cultures actively sustained metabolic activity in a 6-OHDA-induced Parkinson's disease (PD) cell model, only hCVC-derived CMs significantly reduced neurotoxin-induced apoptosis. In conclusion, this study demonstrates that naïve hAFCs and hCVCs may enhance cell-recovery following neuronal damage through multiple rescue mechanisms, and may provide a suitable means of stem cell therapy for neurodegenerative disorders including PD.
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Women may be more vulnerable to certain stress-related psychiatric illnesses than men due to differences in hypothalamic-pituitary-adrenocortical (HPA) axis function. To investigate potential sex differences in forebrain regions associated with HPA axis activation in rats, these experiments utilized acute exposure to a psychological stressor. Male and female rats in various stages of the estrous cycle were exposed to 30min of restraint, producing a robust HPA axis hormonal response in all animals, the magnitude of which was significantly higher in female rats. ⋯ Dual fluorescence in situ hybridization analysis of neurons containing c-fos and corticotropin-releasing factor (CRF) mRNA in these regions revealed significantly more c-fos and CRF single-labeled neurons, as well as significantly more double-labeled neurons in females. Surprisingly, there was no effect of the estrous cycle on any measure analyzed, and an additional experiment revealed no demonstrable effect of estradiol replacement following ovariectomy on HPA axis hormone induction following stress. Taken together, these data suggest sex differences in HPA axis activation in response to perceived threat may be influenced by specific populations of CRF neurons in key stress-related brain regions, the BSTav, MPOA, and PVN, which may be independent of circulating sex steroids.
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Seasonal affective disorder (SAD) is a major depressive disorder that recurs in the fall and winter when day-length gets short. It is well accepted that day-length is encoded by the principal circadian clock located in the suprachiasmatic nucleus (SCN), but very little is known about day-length encoding in diurnal mammals. The present study utilized the grass rat, Arvicanthis niloticus, to investigate how the circadian system responds to photoperiodic changes in a diurnal mammal that shows day-length-dependent mood changes. ⋯ The depression-like behaviors were assessed using sweet solution preference (SSP) and forced swimming test (FST). Animals in the SP group showed decreased SSP and increased immobility time in FST as compared to the EP group, suggesting a depressive phenotype. The present study serves as the first step toward exploring the role that the circadian system plays in SAD using a diurnal rodent model.
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The cholinergic system plays important roles in neurotransmission in both the peripheral and central nervous systems. The cholinergic neurotransmitter acetylcholine is synthesized by choline acetyltransferase (ChAT) and its action terminated by acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The predominance of AChE has focused much attention on understanding the relationship of this enzyme to ChAT-positive cholinergic neurons. ⋯ BuChE-positive neurons without ChAT were found in close proximity with ChAT-positive neuropil in areas such as the thalamus and amygdala. BuChE-positive neuropil was also found closely associated with ChAT-positive neurons, particularly in tegmental nuclei of the pons. These observations provide further neuroanatomical evidence of a role for BuChE in the regulation of acetylcholine levels in the CNS.