Expression patterns of prosaposin and its receptors, G protein-coupled receptor (GPR) 37 and GPR37L1, in the mouse olfactory organ

Prosaposin is a glycoprotein conserved widely in vertebrates, because it is a precursor for saposins that are required for normal lysosomal function and thus for autophagy, and acts as a neurotrophic factor. Most tetrapods possess two kinds of olfactory neuroepithelia, namely, the olfactory epithelium (OE) and the vomeronasal epithelium (VNE). This study examined the expression patterns of prosaposin and its candidate receptors, G protein-coupled receptor (GPR) 37 and GPR37L1, in mouse OE and VNE by immunofluorescence and in situ hybridization. Prosaposin immunoreactivity was observed in the olfactory receptor neurons, vomeronasal receptor neurons, Bowman's gland (BG), and Jacobson's gland (JG). Prosaposin expression was mainly observed in mature neurons. Prosaposin mRNA expression was observed not only in these cells but also in the apical region of the VNE. GPR37 and GPR37L1 immunoreactivities were found only in the BG and/or the JG. Prosaposin was suggested to secrete and facilitate the autophagic activities of the neurons and modulate the mucus secretion in mouse olfactory organ.

Expression of paired box protein PAX7 in prepubertal boar testicular gonocytes

Spermatogenesis involves mitosis, meiosis, growth, and differentiation of spermatogonial stem cells (SSCs), which are capable of self-renewal and differentiation into spermatozoa. Markers of spermatogonia and other spermatogenic cells have been extensively studied in rodents, whereas physiological characteristics and stage-specific markers of germ cells remain largely unknown in large domestic animals. In rodents, paired box protein 7 (PAX7) is known to be a specific marker of a rare spermatogonial subpopulation in adult testes, while being expressed by a large proportion of neonatal testicular germ cells. However, the expression of PAX7 has not yet been investigated in domestic animals. The objective of this study was to characterize PAX7 expression during boar testis development and in in vitro cultured porcine SSCs (pSSCs). Notably, the expression of PAX7 was positively correlated with that of a known boar testis spermatogonial and gonocyte marker, protein gene product 9.5 (PGP9.5), in prepubertal (5-day-old) boar testes but was not observed during or following puberty. Furthermore, the early-stage spermatogonial markers GDNF family receptor alpha-1 (GFRα1) and Sal-like protein 4 (SALL4) were coexpressed in PAX7⁺ testicular cells from 5-day-old boars. PAX7 expression was also maintained in in vitro cultured undifferentiated porcine spermatogonia, with both PAX7 and PGP9.5 strongly expressed in pSSC colonies but not in feeder cells (testicular somatic cells). These data demonstrated that PAX7 expression only occurred in boar testes during prepuberty and was mainly restricted to very early-stage spermatogonial germ cells, such as gonocytes, which implies that PAX7 can be used as a boar gonocyte marker.

Expression patterns and role of SDF-1/CXCR4 axis in boar spermatogonial stem cells

The signaling of chemokine stromal cell-derived factor (SDF)-1 and its receptor C-X-C motif chemokine receptor 4 (CXCR4) is involved in the cellular proliferation, survival, and migration of various cell types. Although SDF-1/CXCR4 has been implicated in the maintenance of the spermatogonial population during mouse testis development, their expression patterns and functions in boar testis remain unclear. In the present study, the expression pattern of SDF-1 and CXCR4 was determined during pre-pubertal and post-pubertal stage boar testes and in vitro cultured porcine spermatogonial stem cells (pSSCs). The role of these proteins in colony formation in cultured pSSCs was also investigated. Interestingly, SDF-1 expression was observed in PGP 9.5-positve spermatogonia in all developing stages of boar testis; however, CXCR4 expression was only detected in spermatogonia from 5-day-old boar testis. In addition, SDF-1 and CXCR4 expression was observed in cultured pSSCs from 5-day-old boar testes, and inhibition of the CXCR4 receptor signaling pathway by AMD3100 significantly decreased the colony formation of pSSCs. These results suggest that SDF-1 and CXCR4 are useful markers for detecting stage-specific spermatogonia in boar testis. Our results reveal the role of the SDF-1/CXCR4 axis in pSSC in vitro culture.

Co-expression of vasoactive intestinal peptide and protein gene product 9.5 surrounding the lumen of human Schlemm's canal

Previous studies of aqueous humor outflow have focused primarily on resistance at the trabecular meshwork (TM), and little is known about the function of Schlemm's canal (SC). Here, we aimed to investigate whether SC is innervated by the peripheral nervous system. Ten eye specimens from eight donors were processed for histological analysis. CD31 was used to identify SC, after which we used protein gene product (PGP) 9.5 as a marker to detect nerve fibers around SC. We then characterized the nerves by double staining for PGP9.5 and sympathetic nerve markers, such as tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DβH), or the parasympathetic marker vasoactive intestinal peptide (VIP), as well as sensory nerve marker calcitonin gene-related peptide (CGRP) and vesicular glutamate transporter 2 (VGLUT2). Immunohistochemistry and immunofluorescence were also performed to detect the expression of γ-epithelial Na⁺ channel (γ-ENaC) in SC. We found that different markers were expressed in the anterior chamber angle, with the luminal surface of SC were only positive stained for PGP9.5, VIP, and γ-ENaC. CGRP and VGLUT2 were expressed in TM and scleral spur (SS), whereas TH and DβH were absent in both TM and SC. Furthermore, PGP9.5 was co-expressed with VIP and γ-ENaC in the region surrounding the SC as well as in SS. Our findings indicate that the peripheral nerves anatomically spread in the tissues around the SC and the local nerve fibers may be parasympathetic or sensory rather than sympathetic.

Species-specific expression of phosphoglycerate kinase 2 (PGK2) in the developing porcine testis

Whereas stage-specific markers for spermatogonial cells have been well investigated in mouse, the specific markers of germ cells in the testis of domestic animals have not been well defined. Phosphoglycerate kinase (PGK), an enzyme that converts 1,3-bisphosphoglycerate and adenosine diphosphate to 3-phosphoglycerate and adenosine triphosphate, has two isozymes: PGK1 and PGK2. In mouse, PGK1 exists only during the early stages of spermatogenesis, and PGK2 is then expressed during the pachytene spermatocyte stage. In this study, we investigated the localization of PGK2 in the developing porcine testis, and compared the similarities and differences in its expression with that of the PGK2 in mouse. The PGK2 protein was found to be exclusively expressed in spermatids of the adult mouse testis, whereas PGK2-positive cells were observed in the prepubertal and postpubertal testes of pigs. Based on this result, we examined the expression of PGK2 in in vitro-cultured porcine undifferentiated spermatogonia and found it to be maintained in the cultured cells. To verify this result and identify the spermatogonial stem cell-like potential in recipient testes, PKH26 dye-stained PGK2-positive cells were transplanted into the testes of busulfan-treated immunodeficient mouse that had been depleted of both testicular germ cells and somatic cells. The transplanted cells colonized the recipient testis at 8 weeks post transplantation, and fluorescence microscopy identified the cells in the basement membranes of the seminiferous tubules of the injected mouse. Taken together, our results suggest that PGK2 is expressed differently in the testes of mouse and pigs according to developmental stage. This finding should contribute to the study of spermatogenesis and the production of transgenic domestic animals through in vitro spermatogonial sperm cell culture.

Redistribution of voltage-gated sodium channels after nerve decompression contributes to relieve neuropathic pain in chronic constriction injury

Nerve decompression is an important therapeutic strategy to relieve neuropathic pain and promote the peripheral nerve regeneration. To address these issues, we investigated the effects of nerve decompression on relief of neuropathic pain behaviors, redistribution of voltage-gated sodium channels (VGSCs), and skin reinnervation with chronic constriction injury (CCI). At post-operative week (POW) 4, animals were divided into a decompression group, in which the ligatures were removed, and a CCI group, in which the ligatures remained. Thermal hyperalgesia and mechanical allodynia at POW 8 had distinct reductions in decompression group compared to CCI group. At that time in CCI group, morphological evidence of pan VGSCs (Pan Nav) and isoforms of VGSCs (Nav1.6, Nav1.9, except for Nav1.8) were shown the widely distribution along the injured sciatic nerve. All of the VGSCs in decompression group became clustering around the node of Ranvier, similar to the pattern of control sciatic nerve at POW 8. Skin reinnervation was demonstrated by epidermal nerve density (END) for protein gene product 9.5 (PGP 9.5)-immunoreactive (IR) nerve fibers and a significant difference between groups only at POW 24 (p=0.01). Growth-associated protein 43 (GAP-43) is participated in the nerve fiber growth and sprouting, a difference in END for GAP-43-IR nerve fibers at POW 24 between groups were also significant (p=0.02). These observations demonstrated that nerve decompression was accompanied with the disappearance of neuropathic pain behaviors after CCI. Morphological studies provided the evidence that redistribution of VGSCs along the injured sciatic nerve but still with an incomplete skin reinnervation. These significant findings demonstrated a role of VGSCs in the pathogenesis of neuropathic pain, and gave an approaching in pharmacological basis of therapeutics.

Loss of nerve fibers in the oviduct isthmus in women with hydrosalpinx

Apart from the abnormalities of tubal anatomy, the main concern linked to infertility is impaired tubal motility associated with hydrosalpinx, which is thought to be controlled by hormones and nerves. The objective of this study was to determine the distribution of nerve fibers in the oviduct isthmus in women with and without hydrosalpinx. Histological sections of the oviduct isthmus tissue were obtained from 18 women undergoing salpingectomy for hydrosalpinx, and from 15 women undergoing hysterectomy and salpingectomy for benign gynecologic diseases. The tissues were immunohistochemically stained for protein gene product (PGP) 9.5, protein S100, neuropeptide tyrosine (NPY), and vasoactive intestinal peptide (VIP) to reveal all nerve fibers, as well as sympathetic and parasympathetic nerve fibers, in the oviduct isthmus. We detected the presence of PGP9.5, S100, VIP, and NPY-immunoreactive nerve fibers in the oviduct isthmus in all study subjects. However, the densities of PGP9.5, S100, VIP, and NPY-immunoreactive nerve fibers in the oviduct isthmus were all significantly decreased in women with hydrosalpinx compared with those in women without hydrosalpinx (P<0.01). Our results suggest that reduced nerve fibers in the oviduct isthmus in women with hydrosalpinx compared with women without hydrosalpinx may have an important function in the mechanism of hydrosalpinx-associated infertility.