Missing self which lacked the expression of MHC class I antigens was prepared in irradiated B6.Ly5.1 mice (H-2^b) which had undergone bone marrow transplantation (BMT) (depleted of T cells) of TAP-1 (−/−) (Ly5.2, H-2^b) mice. Donor cells (Ly5.2⁺) and recipient cells (Ly5.1⁺) were identified by Ly5 markers. For purposes of comparison, syngeneic (B6.Ly5.2 mice) BMT and allogeneic (BALB/c mice, H-2^d) BMT were also conducted. In the case of missing self cells, the ratio of expanding donor cells increased in the liver, spleen and bone marrow on days 14 and 21 after BMT. Such donor cells were mainly NK cells and NKT cells, especially in the liver. The interacting recipient lymphocytes were NKT cells at the early stage (day 7). However, the major lymphocytes became IL-2Rβ⁺CD3^int cells which lacking NK1.1 at the fulminant stage (days 14 and 21). At this time, granulocytes expanded prominently. Since IL-2Rβ⁺CD3^int cells (NK1.1⁻) lacked cytotoxicity, the suppression of expanding donor cells might be mediated by granulocytes. Granulocytes were activated by inflammatory cytokines. These results suggest that in addition to NK1.1-expressing cells (e.g., NK and NKT cells), IL-2Rβ⁺CD3^int cells lacking NK1.1 may be also the lymphocyte subset which recognizes MHC class I-deficient self.

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We examined the role of hepatocyte growth factor (HGF) in the chondrogenesis and endochondral ossification in the forelimbs of mouse embryos by use of immunohistochemistry and organ culture system. In the forelimbs of embryonic day 14 (E14) embryos, intense immunoreactivity for HGF was localized to the chondrocytes located in the proliferative and early hypertrophic zones, and moderate to weak immunoreactivity in the resting and late hypertrophic zones of bone anlagen. Immunoreactivity for the HGF receptor, c-Met, was also localized to the chondrocytes in the resting, proliferative and early hypertrophic zones. In the explants of forelimb buds from E10 embryos cultured for 8 days, exogenous HGF added to the culture media enhanced proliferation of chondrocytes in the forelimb bone anlagen. In contrast, the antisense oligodeoxyribonucleotide (ODN) for HGF as well as the specific HGF antagonist NK4 inhibited proliferation of chondrocytes and caused hypertrophic change and collagen X production, the signs of chondrocyte differentiation, in the arm bone anlagen. Furthermore, the antisense ODN and antagonists for HGF caused a complete lack in the formation of cartilaginous hand and digital bone anlagen. These results suggested that HGF functions in stimulating chondrogenesis and preventing endochondral ossification in the forelimbs of mouse embryos.

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Cancer chemotherapy-induced nausea and vomiting have been demonstrated to involve humoral as well as neuronal mechanisms. A leading role of serotonin (5-hydroxytryptamine, 5-HT) in these mechanisms is supported by inhibition of the emesis by 5-HT₃ receptor antagonists. We compared the effects of granisetron, a selective 5-HT₃ receptor antagonist, and vagotomy on c-fos mRNA expression in the nucleus of the solitary tract (NTS) and the area postrema (AP) of the rat caudal brainstem by means of in situ hybridization. The expression of c-fos mRNA in the NTS and AP was significantly elevated 2 h after cisplatin administration. The induction of c-fos expression by cisplatin in the NTS was significantly inhibited by pretreatment with granisetron. In contrast, the c-fos expression in the AP did not differ between the cisplatin group and the granisetron-treated cisplatin group. The degree of the induction of c-fos mRNA expression in both the AP and NTS was similar between the vagotomy and sham operation groups. Our results suggest that the expression of c-fos mRNA in the NTS may be specifically controlled by 5-HT₃ receptors and that nonspecific humoral factors, such as modulation of transcriptional activity, play an important role in c-fos expression in the AP after vagotomy.

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Prostaglandin E (PGE) induces the penile erection in the mammalians. Receptors for PGE were characterized to 4 different subtypes (EP1—4). The effects of agonists for EP1—4 receptors were studied on phenylephrine (PE, 1 μM)-induced contractions in the rabbit penile corpus cavernosum smooth muscle. The EP4 receptor agonist, ONO-AE1-329 (1 pM—10 μM), markedly relaxed the pre-contracted smooth muscle strips in a concentration-dependent fashion (−65 ± 16% relaxation at 10 nM). The EP2 receptor agonists, ONO-AE1-259-01 (1 nM—10 μM) or butaprost (1 nM—10 μM), also relaxed the smooth muscle strips in a concentration dependent fashion (−58 ± 10% relaxation at 10 μM or −53 ± 10% relaxation at 10 μM). The EP1 receptor agonist, ONO-DI-004 (0.01—10 μM), increased the contractility in the smooth muscle strips. A 12 ± 6% increase was observed with 10 μM of the agonist. The EP3 receptor agonist, ONO-AE-248 (0.01—10 μM), however, did not alter the contractility of the smooth muscle strips. The selective EP4 receptor antagonist, ONO-AE3-208 (0.1 μM), inhibited a relaxant response to ONO-AE1-329 (the EP4 receptor agonist) but did not affect a relaxant response to ONO-AE1-259-01 (the EP2 receptor agonist). It is likely that the relaxant effect of ONO-AE1-329 acts on the EP4 receptor. Neither a nitric oxide synthase (NOS) inhibitor, L-NAME (300 μM), nor a soluble guanylyl cyclase inhibitor, ODQ (30 μM), affected the relaxant responses to ONO-AE1-259-01 (0.1—10 μM) or ONO-AE1-329 (0.01 nM—1 μM). In summary, EP4 and/or EP2 receptors mediate relaxations in rabbit corpus cavernosum smooth muscle, and the EP4 relaxant system is higher in relaxant potency than the EP2 system. Furthermore, the relaxations are independent from a nitric oxide (NO)/cGMP signalling pathway.

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Using newly developed ghrelin specific radioimmunoassay (RIA) combined with high performance liquid chromatography (HPLC), expression and release of ghrelin/des-n-octanoyl ghrelin in mouse testicular Sertoli TM4 cells were demonstrated. The expression and release of the peptides were significantly higher than those of Leydig TM3 cells under the condition used. Testosterone (1—100 ng/mL) increased dose-dependently ghrelin release from Leydig TM3 cells but not from Sertoli TM4 cells. Both TM3 and TM4 cells possessed growth hormone secretagogue receptor (GHS-R). Implication of Sertoli cells in ghrelin expression in the testis has never been discussed. Apart from species-specificity or/and age-dependency in expression of ghrelin in different cell types of the testis, the expression and release of the peptide in TM4 cells which were found in this study raise an issue of physiological significance of ghrelin in Sertoli cells of the testis.

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