Parvalbumin-positive Neurons in the Mouse A8 Region were Lesser than those in the Rat

Dopaminergic neurons play crucial roles in various physiological functions, such as reward, goal-directed behavior, memory formation, and pain sensation. One of the main dopaminergic cell groups in the brain is located in the retrorubral field (RRF, A8 region). A recent electrophysiological study using rats revealed that distinct neurons within the A8 region respond to the different degrees of the threat and aversive stimuli, and that the RRF is the origin of neural signals for threat and aversive outcomes. However, neurochemical characterization of the constituents of the A8 region is not enough. The aim of this study is to determine the neurochemical characteristics of these A8 neurons. To examine the neurochemical cellular organization of the A8 region, we performed immunohistochemistry for two GABAergic neuronal markers, parvalbumin (PV) and neuronal nitric oxide synthase (nNOS), in relation to tyrosine hydroxylase, a marker of dopaminergic neurons. We observed that the number of PV-positive neurons in the mouse A8 region was lesser than in rats. Moreover, nNOS-positive neurons were not detected within the A8 region in either species. These results indicate that the neurochemical organization of the A8 region was distinct between mice and rats. In addition, the cellular composition of the A8 dopaminergic cell group was distinct from other dopaminergic cell groups, such as the A9 and A10 region, in both mice and rats. Understanding these differences among species and cell groups is worth noting for translating the results obtained with distinct animal models into a clinical application.journal articl

Novel Targeting to XCR1+ Dendritic Cells Using Allogeneic T Cells for Polytopical Antibody Responses in the Lymph Nodes

Vaccination strategy that induce efficient antibody responses polytopically in most lymph nodes (LNs) against infections has not been established yet. Because donor-specific blood transfusion induces anti-donor class I MHC antibody production in splenectomized rats, we examined the mechanism and significance of this response. Among the donor blood components, T cells were the most efficient immunogens, inducing recipient T cell and B cell proliferative responses not only in the spleen, but also in the peripheral and gut LNs. Donor T cells soon migrated to the splenic T cell area and the LNs, with a temporary significant increase in recipient NK cells. XCR1+ resident dendritic cells (DCs), but not XCR1− DCs, selectively phagocytosed donor class I MHC+ fragments after 1 day. After 1.5 days, both DC subsets formed clusters with recipient CD4+ T cells, which proliferated within these clusters. Inhibition of donor T cell migration or depletion of NK cells by pretreatment with pertussis toxin or anti-asialoGM1 antibody, respectively, significantly suppressed DC phagocytosis and subsequent immune responses. Three allogeneic strains with different NK activities had the same response but with different intensity. Donor T cell proliferation was not required, indicating that the graft vs. host reaction is dispensable. Intravenous transfer of antigen-labeled and mitotic inhibitor-treated allogeneic, but not syngeneic, T cells induced a polytopical antibody response to labeled antigens in the LNs of splenectomized rats. These results demonstrate a novel mechanism of alloresponses polytopically in the secondary lymphoid organs (SLOs) induced by allogeneic T cells. Donor T cells behave as self-migratory antigen ferries to be delivered to resident XCR1+ DCs with negligible commitment of migratory DCs. Allogeneic T cells may be clinically applicable as vaccine vectors for polytopical prophylactic antibody production even in asplenic or hyposplenic individuals

Locally existing endothelial cells and pericytes in ovarian stroma, but not bone marrow-derived vascular progenitor cells, play a central role in neovascularization during follicular development in mice

BACKGROUND: Neovascularization is necessary for follicular growth. Vascularization is first observed in preantral follicles, and thereafter the vasculature markedly increases in follicles undergoing development. Neovascularization includes angiogenesis and vasculogenesis. Vasculogenesis is the formation of new blood vessels by bone marrow-derived endothelial progenitor cells. It is unclear whether vasculogenesis occurs during follicular growth. Blood vessels must be mature to be functional blood vessels. Mature blood vessels are characterized by the recruitment of pericytes. However, it is unclear where pericytes come from and whether they contribute to neovascularization in the follicle during follicular growth. In this study, we investigated whether bone marrow-derived progenitor cells that differentiate into vascular endothelial cells or pericytes contribute to neovascularization during follicular growth. METHODS: A parabiosis model was used in this study. Six-week-old wild-type and transgenic female mice expressing green fluorescent protein (GFP) were conjoined between the lateral abdominal regions to create a shared circulatory system. After 6 weeks, the ovaries were obtained and immunostained for CD31/CD34 (a vascular endothelial cell marker), platelet-derived growth factor receptor-β (PDGFR-β) (a pericyte marker), and GFP (a bone marrow-derived cell marker). RESULTS: Cells that were positive for CD34 and PDGFR-β were observed in the stroma adjacent to the primary or early preantral follicles and in the theca cell layer of the follicles from the late preantral stage to the preovulatory stage. CD31/CD34 and GFP double-positive cells were observed in the theca cell layer of the follicle from the antral stage to the preovulatory stage while the number of double-positive cells in the preovulatory follicles did not increase. PDGFR-β and GFP double-positive cells were observed in the theca cell layer of the preovulatory follicle but not in the smaller follicle. CONCLUSIONS: Locally existing endothelial cells and pericytes in the stroma play a central role in the neovascularization during follicular growth, while bone marrow-derived endothelial cells and pericytes partially contribute to this process

FABP7 expression in normal and stab-injured brain cortex and its role in astrocyte proliferation

Reactive gliosis, in which astrocytes as well as other types of glial cells undergo massive proliferation, is a common hallmark of all brain pathologies. Brain-type fatty acid-binding protein (FABP7) is abundantly expressed in neural stem cells and astrocytes of developing brain, suggesting its role in differentiation and/or proliferation of glial cells through regulation of lipid metabolism and/or signaling. However, the role of FABP7 in proliferation of glial cells during reactive gliosis is unknown. In this study, we examined the expression of FABP7 in mouse cortical stab injury model and also the phenotype of FABP7-KO mice in glial cell proliferation. Western blotting showed that FABP7 expression was increased significantly in the injured cortex compared with the contralateral side. By immunohistochemistry, FABP7 was localized to GFAP+ astrocytes (21% of FABP7+ cells) and NG2+ oligodendrocyte progenitor cells (62%) in the normal cortex. In the injured cortex there was no change in the population of FABP7+/NG2+ cells, while there was a significant increase in FABP7+/GFAP+ cells. In the stab-injured cortex of FABP7-KO mice there was decrease in the total number of reactive astrocytes and in the number of BrdU+ astrocytes compared with wild-type mice. Primary cultured astrocytes from FABP7-KO mice also showed a significant decrease in proliferation and omega-3 fatty acid incorporation compared with wild-type astrocytes. Overall, these data suggest that FABP7 is involved in the proliferation of astrocytes by controlling cellular fatty acid homeostasis

Localization of Melanocortin 1 Receptor in the Substantia Nigra

Recent findings have revealed that melanocortin 1 receptor (MC1R) deficiency leads to Parkinson’s disease-like dopaminergic neurodegeneration in the substantia nigra (SN). However, its precise distribution and expressing-cell type in the SN remain unclear. Therefore, in this study, we analyzed the localization and characteristics of MC1R in the SN using histological methods, including in situ hybridization and immunohistochemistry. Our findings reveal that MC1R was slightly present in dopaminergic neurons in the ventral tier of SN pars compacta dorsal (vSNCD), a region particularly vulnerable to PD-related neurodegeneration. Notably, we discovered that MC1R is highly present in parvalbumin (PV)-positive neurons, which were also vesicular GABA transporter messenger RNA-expressing inhibitory neurons of the lateral SN pars reticulata (lSNR). Intracellular analysis demonstrated that MC1R was present not only in the plasma membrane but also in mitochondrial and endoplasmic reticulum membranes. Furthermore, MC1R co-localized with attractin (Atrn), a known MC1R modulator, in nearly all MC1R-positive neurons. Therefore, it has been suggested that MC1R and Atrn work together to regulate dopaminergic neurons in the SN through both direct expression and indirect modulation via PV-positive inhibitory neurons. These findings provide new insights into MC1R’s role in the SN and its potential contribution to PD pathophysiolog

Selective involution of thymic medulla by cyclosporine A with a decrease of mature thymic epithelia, XCR1+ dendritic cells, and epithelium-free areas containing Foxp3+ thymic regulatory T cells

AbstractImmunosuppressive drugs such as cyclosporine A (CSA) can disrupt thymic structure and functions, ultimately inducing syngeneic/autologous graft-versus-host disease together with involuted medullas. To elucidate the effects of CSA on the thymus more precisely, we analyzed the effects of CSA on the thymus and T cell system using rats. In addition to confirming the phenomena already reported, we newly found that the proportion of recent thymic emigrants also greatly decreased, suggesting impaired supply. Immunohistologically, the medullary thymic epithelial cells (mTECs) presented with a relative decrease in the subset with a competent phenotype and downregulation of class II major histocompatibility complex molecules. In control rats, thymic dendritic cells (DCs) comprised two subsets, XCR1+SIRP1α−CD4− and XCR1−SIRP1α+CD4+. The former had a tendency to selectively localize in the previously-reported epithelium-containing areas of the rat medullas, and the number was significantly reduced by CSA treatment. The epithelium-free areas, another unique domains in the rat medullas, contained significantly more Foxp3+ thymic Tregs. With CSA treatment, the epithelium-free areas presented strong involution, and the number and distribution of Tregs in the medulla were greatly reduced. These results suggest that CSA inhibits the production of single-positive thymocytes, including Tregs, and disturbs the microenvironment of the thymic medulla, with a decrease of the competent mTECs and disorganization of epithelium-free areas and DC subsets, leading to a generation of autoreactive T cells with selective medullary involution.</jats:p