scholarly journals Cytochemical Studies of the Effects of Activin on Gonadotropin-releasing Hormone (GnRH) Binding by Pituitary Gonadotropes and Growth Hormone Cells

1997 ◽  
Vol 45 (12) ◽  
pp. 1603-1610 ◽  
Author(s):  
Gwen V. Childs ◽  
Geda Unabia
Keyword(s):  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Gonadotropin Releasing Hormone ◽  
Target Cells ◽  
Pituitary Cells ◽  
Releasing Hormone ◽  
Average Area ◽  
Gnrh Receptors ◽  
Gh Cells

Activin stimulates the synthesis and secretion of follicle-stimulating hormone (FSH). It inhibits the synthesis and release of growth hormone (GH). It acts on gonadotropes by stimulating the synthesis of gonadotropin-releasing hormone (GnRH) receptors. To test activin's effects on GnRH target cells, pituitary cells from diestrous or proestrous rats were exposed to media with and without 60 ng/ml activin for 24 hr and stimulated with biotinylated GnRH (Bio-GnRH). The populations were double-labeled for Bio-GnRH and/or luteinizing hormone-β (LH-β), FSH-β, or GH antigens. In both diestrous and proestrous rats, activin stimulated more LH and FSH cells and increased the percentages of GnRH target cells. In diestrous rats, activin stimulated increases in the average area and density of Bio-GnRH label on target cells. In addition, more FSH, LH, and GH cells bound Bio-GnRH. The increment in binding by gonadotropes was not as great as that normally seen from diestrus to proestrus, suggesting that additional factors (such as estradiol) may be needed. These data suggest that activin plays an important role in the augmentation of Bio-GnRH target cells normally seen before ovulation. Its actions on GH cells may reflect a role in the transitory change from a somatotrope to a somatogonadotrope that is seen from diestrus to proestrus.

scholarly journals Annual Change of Reproductive Hormones in Female Angora Goats

2017 ◽  
Vol 5 (4) ◽  
pp. 343
Author(s):  
Erkan Pehlivan ◽  
Hüseyin Polat ◽  
Gürsel Dellal
Keyword(s):  
Luteinizing Hormone ◽  
Repeated Measures ◽  
Follicle Stimulating Hormone ◽  
Reproductive Hormones ◽  
Gonadotropin Releasing Hormone ◽  
Blood Samples ◽  
Releasing Hormone ◽  
Angora Goats ◽  
Turkish State ◽  
Stimulating Hormone

In this research, annual changes of melatonin, gonadotropin-releasing hormone, follicle stimulating hormone, luteinizing hormone, estrogen, testosterone and progesterone were studied on 6 heads of 1.5 years old female Angora goat. To determine hormones concentrations, blood samples were taken from jugular vein of each goat in every month for a year. The blood samples were centrifuged at 4000xg for 5 min. and serum was stored at -20°C until analyses time. Hormones analyses in the serum were performed by enzyme immunoassay (EIA) method. Monthly climatic values and photoperiod were obtained from the Turkish State Meteorological Service and temperature-humidity index was calculated with climatic values. In the study, in order to determine any possible differences in the observed hormones concentrations with respect to months, repeated measures ANOVA analysis was performed. As a result of statistical analysis, there were no significant differences among the months for gonadotropin-releasing hormone, follicle stimulating hormone and testosterone concentration, while significant differences were found among the months for melatonin, luteinizing hormone and progesterone, and estrogen concentration in female Angora goats. According the results of this study, could be concluded that the releases of reproductive hormones examined in female Angora goats was seasonally dependent.

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