博士(獣医学)

Fertility decreases during aging in human and bovine females, but the exact pathophysiological mechanisms in the oviducts and uteri are not clarified yet. Anti- Müllerian hormone (AMH) is a glycoprotein that belongs to the transforming growth factor -β superfamily. Plasma AMH concentration can predict the fertility of adult female goats, ewes, cows, and women via unknown physiological mechanisms. This thesis study attempted to clarify whether AMH, and the main receptor for AMH, AMH receptor type 2 (AMHR2) have important roles for the age-related infertility. In first, I investigated whether the primary receptor for AMH, AMHR2, is expressed in bovine oviducts and endometria. Reverse transcription polymerase chain reaction (RTPCR) detected expression of AMHR2 mRNA in oviductal and endometrial specimens. Western blotting and immunohistochemistry were performed to analyse AMHR2 protein expression using anti-bovine AMHR2 antibody. Immunohistochemistry revealed robust AMHR2 expression in the tunica mucosa of the ampulla and isthmus, as well as in the glandular and luminal epithelium of the endometrium. The number of AMHR2-positive fibroblasts increased, suggesting the presence of fibrosis in the oviducts and uteri of old cows. AMHR2 mRNA (measured RT-qPCR) and AMHR2 protein expression in these layers did not significantly differ among oestrous phases in adult Japanese Black (JB) cows (P>0.1). In addition, AMHR2 mRNA and protein expression in these layers did not differ Among old Holsteins (mean (±SEM age 91.9±6.4 months ) and young (26.6±0.8 months) and old (98.8±10.2 months) JB cows. Therefore, AMHR2 is expressed in bovine oviducts and endometria. Other important hormones for endocrinological regulation have paracrine and autocrine roles. Therefore, in the next study, I investigated whether bovine oviducts and endometria produce AMH. RT-PCR and western blotting detected AMH expression in oviductal and endometrial specimens. Immunohistochemistry revealed robust AMH expression in the ampulla and isthmus epithelia, and the glandular and luminal endometrial epithelia (caruncular endometria). The number of AMH-positive fibroblasts increased, suggesting the presence of fibrosis in the oviducts and uteri of old cows. AMH mRNA and protein expression in these layers did not significantly differ among estrous phases in adult JB heifers (p > .1). Furthermore, the expression in these layers also did not differ among Holstein cows (93.8 ± 5.8 months old), JB heifers (25.5 ± 0.4 months old), and JB cows (97.9 ± 7.9 months old). We also compared AMH concentrations in the oviduct and uterine horn fluids among the three groups (measured by immunoassays). Interestingly, the AMH concentration in the oviduct fluid, but not in the uterine horn fluid, of Holstein cows was lower than those in JB heifers and cows (p < .05). Therefore, bovine oviducts and endometria express AMH and likely secrete it into the oviduct and uterine fluids. Collagen, the most abundant extra-cellular matrix in oviducts and uteri, performs critical roles in pregnancies. I hypothesised that the locations and amounts of both denatured collagen and the collagen-specific molecular chaperone 47-kDa heat shock protein (HSP47) in the oviducts and uteri of old cows are different compared with those of young heifers because of repeated pregnancies. Since detecting damaged collagen in tissues is challenging, we developed a new method that uses a denatured collagen detection reagent. Then, we compared damaged collagen in the oviducts and uteri between postpubertal growing nulliparous heifers (22.1 ± 1.0 months old) and old multiparous cows (143.1 ± 15.6 months old). Further, I evaluated the relationship between denatured collagen and HSP47 by combining this method with fluorescence immunohistochemistry. Picro sirius red staining showed collagen in almost all parts of the oviducts and uteri. Expectedly, damaged collagen was increased in the oviducts and uteri of old cows. However, damaged collagen and HSP47 were not located in the same area in old cows. The number of HSP47- positive fibroblasts increased, suggesting the presence of fibrosis in the oviducts and uteri of old cows. These organs of old cows showed higher HSP47 protein amounts than those of heifers. However, the uteri, but not oviducts, of old cows had lower HSP47 mRNA amounts than those of heifers. These findings revealed the specific location and amounts of denatured collagen and HSP47 in the oviducts and uteri of old cows compared with those of heifers. Therefore, I discovered the AMH, AMHR2 expression in several important layers of oviducts and uteri, and I discovered the increased AMH, AMHR2, and HSP47 in the fibroblasts after aging. However, still role of AMH, AMHR2 in oviducts and uteri were not clarified yet. Therefore, in the next study, I hypothesized that AMH stimulate HSP47 expression in fibroblast and epithelium. I cultured uterine fibroblasts and epithelial cells obtained from heifers. Then, I treated the cells with recombinant with increasing concentrations (0, 1, 10, or 100 ng mL-1) of AMH. HSP47 expression was measured by western blotting. AMH stimulated (P<0.05) HSP47 expression in epithelial cells but not in fibroblasts. Therefore, these findings suggested the role of AMH to cause the abnormal high HSP47 expression in the oviducts and uteri of old cows. In conclusion, this thesis discovered the AMH and AMHR2 in bovine oviducts and uteri, which have important roles for collagen synthesis via HSP47.

近年、イヌ・ネコ・フェレットといった様々な動物が愛玩動物として飼育されており、ヒトと同様に多様な感染症に罹ることが知られている。愛玩動物における感染症の治療法や診断法を確立することはOne Healthの観点でも重要で、ヒトの健康の維持に直結するような公衆衛生上重要な課題である。ネコヘルペスウイルス1（FHV-1）は猫ウイルス性鼻気管炎の原因となるヘルペスウイルスとして知られ、上部呼吸器症状や流産などを引き起こす。インフルエンザAウイルス（IAV）は人において呼吸器症状を引き起こす季節性のウイルスとして知られ、イヌ・ネコ・ブタといった様々な動物に感染することが知られている。季節性のIAV以外にも、動物の体内で生まれる遺伝子再集合体のパンデミックも問題となる。本研究では、愛玩動物に感染が認められる上記の2種類のウイルスを解析し、FHV-1の新規治療薬の提案とIAVの診断法の確立を目的とし、全2章で構成された。