Chemoarchitecture of glial fibrillary acidic protein (GFAP) and glutamine synthetase in the rat optic nerve: an immunohistochemical study.

An immunohistochemical analysis of the chemoarchitecture of glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) was conducted in the rat optic nerve. The optic nerve has been divided into 3 regions: the intraretinal, unmyelinated, and myelinated regions. However, it currently remains unclear whether the chemoarchitecture of GFAP and GS is homogeneously organized, especially in the myelinated region. The intraretinal region was divided into intraretinal regions 1 (i1) and 2 (i2). GFAP immunoreactivity was very strong in the i2 and unmyelinated regions, and strong in the i1 region. GS immunoreactivity was moderate in the i1 and i2 regions, and weak in the unmyelinated region. The myelinated region was separated into myelinated regions 1 (m1) and 2 (m2). In the m1 region, GFAP immunoreactivity was strong and GS immunoreactivity was moderate; however, GFAP immunoreactivity was moderate and GS immunoreactivity was weak in the m2 region. Thus, the chemoarchitecture was heterogeneously organized in the myelinated region, with the i1, i2 and m1 regions being the main GS distribution sites. Moreover, most GS-immunoreactive glial cells were oligodendrocytes in the myelinated region. Since GS is a key enzyme in glutamate metabolism, these results may facilitate future investigations for a clearer understanding of glutamate metabolism.

Chemoarchitecture of glial fibrillary acidic protein (GFAP) and glutamine synthetase in the optic nerve of the monkey (Macaca fuscata): An immunohistochemical study.

An immunohistochemical analysis of the chemoarchitecture of glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) was conducted in the monkey optic nerve. The optic nerve has been divided into 3 regions: the prelaminar, lamina cribrosa, and retrolaminar regions. However, it currently remains unclear whether the chemoarchitecture of GFAP and GS is homogeneously organized, especially in the retrolaminar region. Strong-to-moderate GFAP immunoreactivity was observed in all 3 regions. The retrolaminar region was further divided into anterior (RLa) and posterior (RLp) retrolaminar regions. More GFAP immunoreactive punctations were observed in the RLa region than in the RLp region. Regarding GS immunoreactivity, moderately GS immunoreactive glial cells were observed in the prelaminar and retrolaminar regions. In the retrolaminar region, there were more of these cells in the RLa region than in the RLp region. GS immunoreactivity was markedly weaker in the prelaminar and retrolaminar regions than in the retina. Thus, the chemoarchitecture of GFAP and GS was heterogeneously organized in the retrolaminar region, and the RLa region was the main GS distribution site in the retrolaminar region. Since GS is a key enzyme of glutamate metabolism, these results may provide clues as to how glutamate is metabolized in the primate optic nerve.

Wolfram syndrome 1 (Wfs1) mRNA expression in the normal mouse brain during postnatal development.

Wolfram syndrome is a rare genetic disorder accompanying diabetes insipidus, sensorineural hearing loss, neurological complications, and psychiatric illness. This syndrome has been attributed to mutations in the WFS1 gene. In this study, we made a detailed histochemical analysis of the distribution of Wfs1 mRNA in the brain of developing mice. There were three patterns of change in the strength of Wfs1 mRNA signals from birth to early adulthood. In type 1, the signals were weak or absent in neonates but strong or moderate in young adults. This pattern was observed in the CA1 field, parasubiculum, and entorhinal cortex. In type 2, the signals were of a relatively constant strength during development. This pattern was seen in limbic structures (e.g. subiculum and central amygdaloid nucleus) and brainstem nuclei (e.g. facial and chochlear nuclei). In type 3, the signals peaked in the second week of age. This pattern was observed in the thalamic reticular nucleus. Thus, Wfs1 mRNA was widely distributed in the normal mouse brain during postnatal development. This evidence may provide clues as to the physiological role of the Wfs1 gene in the central nervous system, and help to explain endocrinological, otological, neurological, and psychiatric symptoms in Wolfram syndrome patients.

Wolfram syndrome 1 (Wfs1) gene expression in the normal mouse visual system.

Wolfram syndrome (OMIM 222300) is a neurodegenerative disorder defined by insulin-dependent diabetes mellitus and progressive optic atrophy. This syndrome has been attributed to mutations in the WFS1 gene, which codes for a putative multi-spanning membrane glycoprotein of the endoplasmic reticulum. The function of WFS1 (wolframin), the distribution of this protein in the mammalian visual system, and the pathogenesis of optic atrophy in Wolfram syndrome are unclear. In this study we made a detailed analysis of the distribution of Wfs1 mRNA and protein in the normal mouse visual system by using in situ hybridization and immunohistochemistry. The mRNA and protein were observed in the retina, optic nerve, and brain. In the retina, Wfs1 expression was strong in amacrine and Müller cells, and moderate in photoreceptors and horizontal cells. In addition, it was detectable in bipolar and retinal ganglion cells. Interestingly, moderate Wfs1 expression was seen in the optic nerve, particularly in astrocytes, while little Wfs1 was expressed in the optic chiasm or optic tract. In the brain, moderate Wfs1 expression was observed in the zonal, superficial gray, and intermediate gray layers of the superior colliculus, in the dorsomedial part of the suprachiasmatic nucleus, and in layer II of the primary and secondary visual cortices. Thus, Wfs1 mRNA and protein were widely distributed in the normal mouse visual system. This evidence may provide clues as to the physiological role of Wfs1 protein in the biology of vision, and help to explain the selective vulnerability of the optic nerve to WFS1 loss-of-function.

Endoplasmic reticulum stress induces Wfs1 gene expression in pancreatic beta-cells via transcriptional activation.

OBJECTIVE: The WFS1 gene encodes an endoplasmic reticulum (ER) membrane-embedded protein. Homozygous WFS1 gene mutations cause Wolfram syndrome, characterized by insulin-deficient diabetes mellitus and optic atropy. Pancreatic beta-cells are selectively lost from the patient's islets. ER localization suggests that WFS1 protein has physiological functions in membrane trafficking, secretion, processing and/or regulation of ER calcium homeostasis. Disturbances or overloading of these functions induces ER stress responses, including apoptosis. We speculated that WFS1 protein might be involved in these ER stress responses. DESIGN AND METHODS: Islet expression of the Wfs1 protein was analyzed immunohistochemically. Induction of Wfs1 upon ER stress was examined by Northern and Western blot analyses using three different models: human skin fibroblasts, mouse pancreatic beta-cell-derived MIN6 cells, and Akita mouse-derived Ins2 (96Y/Y) insulinoma cells. The human WFS1 gene promoter-luciferase reporter analysis was also conducted. RESULT: Islet beta-cells were the major site of Wfs1 expression. This expression was also found in delta-cells, but not in alpha-cells. WFS1 expression was transcriptionally up-regulated by ER stress-inducing chemical insults. Treatment of fibroblasts and MIN6 cells with thapsigargin or tunicamycin increased WFS1 mRNA. WFS1 protein also increased in response to thapsigargin treatment in these cells. WFS1 gene expression was also increased in Ins2 (96Y/Y) insulinoma cells. In these cells, ER stress was intrinsically induced by mutant insulin expression. The WFS1 gene promoter-luciferase reporter system revealed that the human WFS1 promoter was activated by chemically induced ER stress in MIN6 cells, and that the promoter was more active in Ins2 (96Y/Y) cells than Ins2 (wild/wild) cells. CONCLUSION: Wfs1 expression, which is localized to beta- and delta-cells in pancreatic islets, increases in response to ER stress, suggesting a functional link between Wfs1 and ER stress.

Neuroanatomical distribution of Huntingtin-associated protein 1-mRNA in the male mouse brain.

Huntingtin-associated protein 1 (HAP1) was identified as an interactor of the gene product (Huntingtin) responsible for Huntington's disease and found to be a core component of the stigmoid body. Even though HAP1 is highly expressed in the brain, detailed information on HAP1 distribution has not been fully described. Focusing on the neuroanatomical analysis of HAP1-mRNA expression using in situ hybridization histochemistry, the present study clarified its detailed regional distribution in the entire mouse brain. Mouse HAP1 (Hap1)-mRNAs were abundantly expressed in the limbic-related forebrain regions and midline/periventricular brainstem regions including the olfactory bulb, limbic-associated cortices, hippocampus, septum, amygdala, bed nucleus of the stria terminalis, preoptico-hypothalamic regions, central gray, raphe nuclei, locus coeruleus, parabrachial nuclei, nucleus of the solitary tract, and area postrema. In contrast, little expression was detected in the striatum and thalamus, implying that Hap1 is associated with neurodegeneration-sparing regions rather than target lesions in Huntington's disease. The distribution pattern, resembling that of the stigmoid body, suggests that HAP1 and the stigmoid body are implicated in protection from neuronal death rather than induction of neurodegeneration in Huntington's disease, and that they play an important role in integrating instinct behaviors and underlying autonomic, visceral, arousal, drive, memory, and neuroendocrinergic functions, particularly during extensive homeostatic or emotional processes. These data will provide an important morphological base for a future understanding of functions of HAP1 and the stigmoid body in the brain.

Expression of estrogen receptors (alpha, beta) and androgen receptor in serotonin neurons of the rat and mouse dorsal raphe nuclei; sex and species differences.

Sex steroids have been inferred to be involved in the regulation of affective status at least partly through the serotonergic (5-HT) system, particularly in the dorsal raphe nucleus (DRN), which innervates enormous projections to the cerebral cortex and limbic system. In the present study, the expression of estrogen receptors-alpha and -beta (ERalpha, ERbeta), androgen receptor (AR) and 5-HT was examined immunohistochemically in the rat and mouse DRN in both sexes. The results showed that large numbers of ERalpha- and/or ERbeta-immunoreactive (ERalpha-I, ERbeta-I) cells were found in the DRN of both male and female mice, whereas only small numbers of ERalpha-I cells and no ERbeta-I cells were seen in the rat DRN of each sex. With respect to AR-immunoreactive (AR-I) cells, moderate numbers of such cells were present only in male rats and mice, and no or very few could be observed in female ones. The ERalpha-I, ERbeta-I, and AR-I cells were mainly distributed in the rostral DRN. In double-immunostaining, many 5-HT-I neurons were found to show ERalpha and/or ERbeta expression specifically in the rostral DRN (particularly dorsal, ventral and interfascicular parts) of mice of both sexes, but not in that of rats. In contrast, only a few 5-HT neurons were observed to show AR expression in the DRN of both rodents. The current results strongly suggest that sex steroids can modulate the affective regulation of the serotonergic system through ERalpha and/or ERbeta in 5-HT neurons of the mouse rostral DRN (but not so much through AR), and that such effects might be different depending on the sex and species, as shown by the prominent sex differences in AR expression and prominent species differences in ERalpha and ERbeta expression.

Gonadal and adrenal effects on the glucocorticoid receptor in the rat hippocampus, with special reference to regulation by estrogen from an immunohistochemical view-point.

Focusing on the hippocampal CA1 region, effects of peripheral gonadal and adrenal steroids on the glucocorticoid receptor (GR) were immunohistochemically evaluated in male and female adult rat brains after adrenalectomy (ADX), gonadectomy (GDX), and administration of estradiol (E2) and/or corticosterone (CS). In ADXed male rats, the hippocampal nuclear GR decreased and turned back to the cytoplasm, whereas in females, nuclear localization persisted even after ADX. In GDX+ADXed female rats, the GR was dispersedly translocated from the nucleus to the cytoplasm as well as in GDX+ADXed males. The dispersed cytoplasmic GR was again translocated into the nucleus by administration of CS. In addition, administration of a small dose of E2 for 4-13 days was found to sufficiently recover the nuclear location of GR in GDX+ADXed rat brains, whereas medium-to-large doses could not do this. Also, a longer administration more strongly enhances the nuclear GR location and expression. The present study provided strong immunohistochemical evidence that the sexually dimorphic effects of ADX on hippocampal GR are attributable to gonadal hormones, and that E2 is implicated in the effects in inversely-dose- and directly-duration-dependent manner. Taken together, intriguing gonadal and adrenal crosstalk is considered to play some important role in regulating hippocampal GR morphology and to have a possibly crucial influence on stress-related disorders such as depression.