This study was undertaken to investigate whether bovine granulosa and theca interna cells could be luteinized in vitro into luteal-like cells. Granulosa and theca cells were cultured for 9 days in the presence of forskolin (10 microM), insulin (2 micrograms/ml), insulin-like growth factor I (100 ng/ml), or a combination of these agents. During the first day of culture, granulosa and theca cells secreted estradiol and androstenedione, respectively; progesterone rose only after 3-5 days in culture and reached a maximum on the ninth day of culture. Cells incubated in the presence of forskolin plus insulin exhibited morphological and functional characteristics of luteal cells isolated from the corpus luteum. It was found that cell diameter, basal and stimulated progesterone secretion, and pattern of cell replication for both cell types were comparable to those of luteal cells. Numerous lipid droplets and intensified mitochondrial adrenodoxin staining also indicated active steroidogenesis in luteinized cells. After 9 days in culture, stimulants were withdrawn, and the culture proceeded in basal medium for an additional 5 days; elevated progesterone levels were maintained by luteinized granulosa cells (LGC), whereas in contrast a dramatic drop in progesterone production was observed in luteinized theca cells (LTC). On Day 9, cells were challenged for 3 h with LH (10 ng/ml), forskolin (10 microM), or cholera toxin (100 ng/ml), resulting in a 4-fold increase in progesterone secretion by LTC; the same treatments failed to stimulate progesterone in LGC.(ABSTRACT TRUNCATED AT 250 WORDS)
The effects of gonadal hormones, testosterone (Te) and estrogen (E2) as factors in the development of the immune system in two lines, high response (HC) and low response (LC), of broiler chickens divergently selected for early or late immune maturation were studied. For this purpose, plasma Te and E2 levels were tested and correlated with immune response. Also, the effects of exogenous administration of gonadal steroids testosterone propionate (TP), dihydrotestosterone (DHT), and estradiol 3-benzoate (EB), and the nonsteroidal androgen antagonist flutomide (Flu) and anti-estrogen tamoxifen (Tam) on the immune system were studied. Male chicks of the LC line had a higher level of endogenous Te during first 30 d posthatch. The administration of TP or DHT had no noticeable effect on the humoral immune response, whereas DHT suppressed growth of the bursa of Fabricius of both sexes of HC line. No differences in the endogenous E2 level were observed between sexes in either line. Administration of EB inhibited comb and testicle growth and enhanced significantly the humoral immune response to Escherichia coli and sheep erythrocytes (SRBC). The anti-androgen Flu and anti-estrogen Tam strongly inhibited humoral immune response to E. coli and SRBC antigen, whereas no effects on comb and testicle growth were observed. The experimental results suggest that gonadal hormones have similar principal posthatch effects in avian as in mammals; however, the gonadal steroids prehatch effects and the genetic-physiological-environmental effects require further study.
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