TY - JOUR
T1 - Gonadotrophin and prolactin secretion in castrated male sheep following subcutaneous or intracranial treatment with testicular hormones
AU - Blache, Dominique
AU - Tjondronegoro, Soedjiharti
AU - Blackberry, Margaret A.
AU - Anderson, Stephen T.
AU - Curlewis, Jonathan D.
AU - Martin, Graeme B.
N1 - Funding Information:
This work was funded by the Australian Research Council and the CSIRO Division of Animal Production. For their assistance during these studies, we would like to thank the Animal Science Group of the University of Westerrl Australia, particularly S. R. D. Sutherland, R. Boukhliq, and D. W. Miller. For supplying the FSH and prolactin assay
PY - 1997
Y1 - 1997
N2 - Interactions between testosterone, estradiol, and inhibin in the control of gonadotrophin secretion in males are poorly understood. Castrated rams were treated with steroid-free bovine follicular fluid (bFF), testosterone, or estradiol and for 7 d (2 x 2 x 2 factorial design). Given independently, none of the exogenous hormones affected follicle-stimulating hormone (FSH) concentrations, but the combination of one or both steroids with bFF reduced FSH secretion. Testosterone and estradiol reduced luteinizing hormone (LH) pulse frequency (there was no synergism), and bFF had no effect. Plasma prolactin concentrations were not affected by any treatment. To locate the central sites of steroid action, castrated rams were bilaterally implanted in the preoptic area (POA), ventromedial nucleus (VMH), or arcuate nucleus (ARC). These implants did not affect FSH or prolactin concentrations, or LH pulse amplitude. The frequency of the LH pulses was not affected by testosterone in any site. Estradiol located in the ARC, but not the POA or VMH, decreased LH pulse frequency. In summary, FSH secretion is controlled by synergistic interactions between inhibin and estradiol or testosterone, whereas GnRH/LH pulse frequency is controlled by testicular steroids. Estradiol acts partly, at least, in the ARC, but the central site of action, testosterone remains unknown.
AB - Interactions between testosterone, estradiol, and inhibin in the control of gonadotrophin secretion in males are poorly understood. Castrated rams were treated with steroid-free bovine follicular fluid (bFF), testosterone, or estradiol and for 7 d (2 x 2 x 2 factorial design). Given independently, none of the exogenous hormones affected follicle-stimulating hormone (FSH) concentrations, but the combination of one or both steroids with bFF reduced FSH secretion. Testosterone and estradiol reduced luteinizing hormone (LH) pulse frequency (there was no synergism), and bFF had no effect. Plasma prolactin concentrations were not affected by any treatment. To locate the central sites of steroid action, castrated rams were bilaterally implanted in the preoptic area (POA), ventromedial nucleus (VMH), or arcuate nucleus (ARC). These implants did not affect FSH or prolactin concentrations, or LH pulse amplitude. The frequency of the LH pulses was not affected by testosterone in any site. Estradiol located in the ARC, but not the POA or VMH, decreased LH pulse frequency. In summary, FSH secretion is controlled by synergistic interactions between inhibin and estradiol or testosterone, whereas GnRH/LH pulse frequency is controlled by testicular steroids. Estradiol acts partly, at least, in the ARC, but the central site of action, testosterone remains unknown.
KW - CNS
KW - Gonadotrophin
KW - Male
KW - Sex steroid
KW - Sheep
UR - http://www.scopus.com/inward/record.url?scp=0031431388&partnerID=8YFLogxK
U2 - 10.1007/bf02778146
DO - 10.1007/bf02778146
M3 - Article
C2 - 9549050
AN - SCOPUS:0031431388
SN - 1355-008X
VL - 7
SP - 235
EP - 243
JO - Endocrine
JF - Endocrine
IS - 2
ER -