Profiles of Circulating Steroid Hormones, Gonadotropins, Immunoreactive Inhibin and Prolactin During Pregnancy in Goats and Immunolocalization of Inhibin Subunits, Steroidogenic Enzymes and Prolactin in the Corpus Luteum and Placenta

Abstract

Abstract. The current study was performed to follow up the circulating hormonal changes and to correlate the findings with the physiological activity of the corpus luteum (CL) and placenta during pregnancy in goats. Blood samples were collected weekly from five goats during pregnancy for measuring steroid and protein hormones. A gradual increase was observed in immunoreactive (ir-) inhibin, with maximal levels at the 17th week. The plasma concentrations of estradiol and prolactin (PRL) showed nearly similar patterns during pregnancy, where they declined to basal levels during the first 4 weeks post-breeding and then increased significantly, with the maximal concentration during late pregnancy. The plasma FSH and LH concentrations were maintained at basal levels throughout the gestation period. The plasma progesterone concentration abruptly increased in the first week post-breeding and remained at high values throughout the pregnancy period. Immunohistochemical localization of inhibin alpha, betaA, betaB and steroidogenic enzymes cytochrome P450 aromatase, 3alpha-hydroxysteroid dehydrogenase (3betaHSD), cytochrome 17alpha-hydroxylase P450 and cholesterol side-chain cleavage cytochrome P450 in the cyclic and pregnant goat CL revealed positive immunoreactivity without affinity differences between the luteal and pregnancy stages. The placental syncytiotrophoblasts also showed positive staining, except for inhibin betaA and 3betaHSD. The giant binucleate cells of the placenta showed positive immunoreactions to PRL. These results suggest that the high concentrations of irinhibin, estradiol and PRL during late pregnancy are of placental origin and that the placenta may have a vital role in the maintenance of pregnancy, regulation of mammary growth and preparation for kidding and lactation in goats. Key words: Goat, Hormone, Inhibin, Placenta, Pregnancy (J. Reprod. Dev. 56: [243][244][245][246][247][248][249][250] 2010) tudying hormonal changes during the gestation period knocks down doors that block understanding of the regulatory mechanisms accompanying fetal development and maintenance of pregnancy; the most important stage of animal reproductive life. In goats, pregnancy is dependant on the corpus luteum (CL) with minimal contribution from placenta. However, day by day, scientists are working hard to discover the additional roles played by the placenta. The pattern of progesterone levels during pregnancy is changeable; it is low from mating until the 6th day [1], increases noticeably by the 3rd week and remains high until the 19th week [2][3][4][5][6][7]. Maintenance of progesterone secretion by the CL during pregnancy in the goat is luteinizing hormone (LH)-dependant; moreover, prolactin (PRL) is synergistic with LH in stimulating this function [8]. The highest concentration of estradiol in the blood is found 2 days before ovulation [1,9]; the concentration decreases during the first 30 days after mating and then increases again between weeks 7 and 11, with the maximal output near parturition [7,10].Up till now,...

Ovarian Expression of Inhibin-Subunits, 3.BETA.-Hydroxysteroid Dehydrogenase, and Cytochrome P450 Aromatase during the Estrous Cycle and Pregnancy of Shiba Goats (Capra hircus)

“…The highhe highest levels of inhibin A were measured during the growth phase of the estrous cycle dominant follicles [14]. In golden hamsters, the ovarian follicles secrete large amounts of inhibin A and inhibin B during the second half of pregnancy [18], and the late stage of pregnancy in goats is associated with an increase in plasma ir-inhibin levels [13]. The present results show that both P450arom and 3βHSD expression in follicles is nearly stable in cyclic and pregnant goats ovarian follicles.…”

“…Earlier studies showed that all luteal cells express P450arom without difference in affinity between the luteal phase and pregnancy, however, weak positive staining was observed in late pregnancy [31] and this was associated with an increase in plasma estradiol levels during mid pregnancy in goats [13]. On the other hand, 3βHSD showed a unique expression in luteal cells characterized by a gradual increase from the luteal phase to late pregnancy, with the maximum intensity being observed during late pregnancy.…”

Secretion of Inhibin during the Estrous Cycle in the Female Asian Elephant (Elephas maximus)

“…Inhibins are produced mainly by the granulosa cells of ovarian follicles when the follicles develop from the small antral to preovulatory stages and suppress follicle stimulating hormone (FSH) secretion [12], such as in rats [10,13], golden hamsters [11,17], guinea pigs [19,20], sheeps [3], goats [7,8], monkeys [18], mares [15,16] and ducks [29,30]. Although changes in circulating inhibin in elephants have been reported [1,2], its cellular sources of ovaries have not been studied yet.…”

Endocrine Mechanisms Responsible for Different Follicular Development During the Estrous Cycle in Hatano High- and Low-avoidance Rats

“…Immunohistochemical analysis was conducted according to previously described methods [5,6]. Briefly, sections were incubated overnight at 4 C with the primary rabbit polyclonal antibody at a dilution of 1:1000.…”

“…After washing (as above), these sections were subsequently incubated with 2% (v/v) avidin-biotin complex (Elite ABC kit) in PBS at 37 C for 45 min and washed as above, and then the reaction products were visualized by treatment with 0.025% (w/v) 3,3′-diaminobenzidine tetrachloride (DAB; Sigma-Aldrich Co., St. Louis, MO, USA) in 0.01 M PBS containing 0.01% (v/v) H 2 O 2 for 1-20 min until a brown color developed. The specificity of each primary polyclonal antibody was examined as above but using normal rabbit serum instead of the primary antibody [5,6]. In order to identify the structural components and cell types within the ovaries, the sections were counterstained with hematoxylin (Wako Pure Chemical Industries, Osaka, Japan).…”