共查询到6条相似文献,搜索用时 15 毫秒
1.
Nahoko IEDA Yoshihisa UENOYAMA Yoko TAJIMA Tomoko NAKATA Masatoshi KANO Yousuke NANIWA Youki WATANABE Shiori MINABE Junko TOMIKAWA Naoko INOUE Fuko MATSUDA Satoshi OHKURA Kei-ichiro MAEDA Hiroko TSUKAMURA 《The Journal of reproduction and development》2014,60(4):312-316
Puberty is associated with an increase in gonadotropin secretion as a result of an increase in gonadotropin-releasing hormone
(GnRH) secretion. Kisspeptin is considered to play a key role in puberty onset in many mammalian species, including rodents,
ruminants and primates. The present study aimed to determine if changes in hypothalamic expression of the KISS1
gene, encoding kisspeptin, are associated with the onset of puberty in pigs. The animals (n=4 in each group) were perfused with 4%
paraformaldehyde at 0, 1, 2, 3 and 4 months old, as prepubertal stages, and at 5 months old, as the peripubertal stage, following
each blood sampling. KISS1 gene expressions in coronal sections of brains were visualized by in
situ hybridization. Plasma luteinizing hormone (LH) was measured by radioimmunoassay. KISS1 mRNA
signals were observed in the arcuate nucleus (ARC) at all ages examined without any significant difference in the number of
KISS1-expressing cells, indicating that the KISS1 gene is constantly expressed in the ARC
throughout pubertal development in pigs. The plasma LH concentration was the highest in 0-month-old piglets and significantly
decreased in the 1- and 2 month-old groups (P<0.05), suggesting a developing negative feedback mechanism affecting gonadotropin
release during the prepubertal period. Considering the potent stimulating effect of kisspeptin on gonadotropin release in
prepubertal pigs, kisspeptin secretion rather than kisspeptin synthesis may be responsible for the onset of puberty in pigs. 相似文献
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3.
Tomomi TANAKA Satoshi OHKURA Yoshihiro WAKABAYASHI Takenobu KUROIWA Kiyosuke NAGAI Natsumi ENDO Akira TANAKA Hisanori MATSUI Masami KUSAKA Hiroaki OKAMURA 《The Journal of reproduction and development》2013,59(6):563-568
The aim of the present study was to determine if the estradiol-induced luteinizing
hormone (LH) surge is influenced by the constant exposure to TAK-683, an
investigational metastin/kisspeptin analog, that had been established to depress the
pulsatile gonadotropin-releasing hormone (GnRH) and LH secretion in goats.
Ovariectomized goats subcutaneously received TAK-683 (TAK-683 group, n=6) or vehicle
(control group, n=6) constantly via subcutaneous implantation of an osmotic pump.
Five days after the start of the treatment, estradiol was infused intravenously in
both groups to evaluate the effects on the LH surge. Blood samples were collected at
6-min intervals for 4 h prior to the initiation of either the TAK-683 treatment or
the estradiol infusion, to determine the profiles of pulsatile LH secretion. They
were also collected at 2-h intervals from –4 h to 32 h after the start of estradiol
infusion for analysis of LH surges. The frequency and mean concentrations of LH
pulses in the TAK-683 group were remarkably suppressed 5 days after the start of
TAK-683 treatment compared with those of the control group (P<0.05). On the other
hand, a clear LH surge was observed in all animals of both groups. There were no
significant differences in the LH concentrations for surge peak and the peak time of
the LH surge between the TAK-683 and control groups. These findings suggest that the
effects of continuous exposure to kisspeptin or its analog on the mechanism(s) that
regulates the pulsatile and surge mode secretion of GnRH/LH are different in
goats. 相似文献
4.
Faidiban Oktofianus RUDOLF Hiroya KADOKAWA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2014,76(12):1623-1625
STX is an agonist for a
recently characterized membrane estrogen receptor whose structure has not been identified.
We evaluated whether STX suppresses gonadotropin-releasing hormone (GnRH)–induced
luteinizing hormone (LH) release from bovine anterior pituitary (AP) cells. We cultured AP
cells (n=12) for 3 days in steroid-free conditions, followed by increasing concentrations
(0.001, 0.01, 0.1, 1 and 10 nM) of 17β-estradiol or STX for 5 min before GnRH stimulation
until the end of the experiment. Estradiol (0.001 to 0.1 nM) significantly suppressed
GnRH-stimulated LH secretion, whereas STX did not affect GnRH-stimulated LH secretion at
any of the tested concentrations. In conclusion, STX, unlike estradiol, possesses no
suppressive effect on GnRH-induced LH release from bovine AP cells. 相似文献
5.
Minami W. OKUYAMA Michito SHIMOZURU Yojiro YANAGAWA Toshio TSUBOTA 《The Journal of reproduction and development》2014,60(2):155-161
The raccoon is a seasonal breeder with a mating season in the winter. In a previous
study, adult male raccoons exhibited active spermatogenesis with high plasma testosterone
concentrations, in the winter mating season. Maintenance of spermatogenesis generally
requires high testosterone, which is produced by steroidogenic enzymes. However, even in
the summer non-mating season, some males produce spermatozoa actively despite low plasma
testosterone concentrations. To identify the factors that regulate testosterone production
and contribute to differences in spermatogenetic activity in the summer non-mating season,
morphological, histological and endocrinological changes in the testes of wild male
raccoons should be known. In this study, to assess changes in the biosynthesis, metabolism
and reactivity of testosterone, the localization and immunohistochemical staining
intensity of four steroidogenic enzymes (P450scc, P450c17, 3βHSD, P450arom) and the
androgen receptor (AR) were investigated using immunohistochemical methods. P450scc and
P450c17 were detected in testicular tissue throughout the year. Seasonal changes in
testosterone concentration were correlated with 3βHSD expression, suggesting that 3βHSD
may be important in regulating the seasonality of testosterone production in raccoon
testes. Immunostaining of P450arom and AR was detected in testicular tissues that
exhibited active spermatogenesis in the summer, while staining was scarce in
aspermatogenic testes. This suggests that spermatogenesis in the raccoon testis might be
maintained by some mechanism that regulates P450arom expression in synthesizing estradiol
and AR expression in controlling reactivity to testosterone. 相似文献
6.
Celina Emiko OKAMOTO-OKUBO Renata Navarro CASSU Jean Guilherme Fernandes JOAQUIM Luciane dos REIS MESQUITA Sheila Canevese RAHAL Hugo S Salvador OLIVEIRA Regina TAKAHIRA Isadora ARRUDA Leandro MAIA Fernanda da CRUZ LANDIM Stelio Pacca Loureiro LUNA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(5):881