02248naa a2200265 a 450000100080000000500110000800800410001902400310006010000150009124501240010626000090023052015080023965000090174765000170175665000150177365000230178865000100181165000140182165300140183565300070184965300230185670000180187970000190189777300660191620712592017-06-22       1988    bl uuuu     u00u1 u    #d7 a10.1677/joe.0.11801932DOI1 aDOBSON, H.  aSuppression of LH response to gonadotrophin-releasing hormone or oestradiol by ACTH(1-24) treatment in anoestrous ewes.  c1988  aAbstract: Stress is known to result in lowered female reproductive efficiency. The objective of this study was to examine how increased pituitary-adrenal activity may influence gonadotrophin release in anoestrous ewes. Various doses (0.06-1.0 mg) of a synthetic adrenocorticotrophic hormone (ACTH(1-24)) preparation were injected into ewes 30 min or 3 h before an i.v. injection of 500 ng gonadotrophin-releasing hormone (GnRH). The LH response to GnRH given 30 min after ACTH(1-24) was similar to that after GnRH alone, whereas the response 3 h after ACTH(1-24) was significantly lower, irrespective of the dose of ACTH(1-24). At 30 min and 3 h after ACTH(1-24) the concentrations of cortisol exceeded 50 nmol/l compared with baseline values of less than 10 nmol/l. The effect of ACTH(1-24) on oestradiol-induced LH release was also examined. Those ewes receiving 0.8 mg ACTH(1-24) depot and 50 micrograms oestradiol benzoate simultaneously had a preovulatory-type increase in LH 14-20 h later, similar to when oestradiol benzoate was given alone. None of the ewes receiving an additional 0.8 mg ACTH(1-24) depot 10 h after oestradiol benzoate had increases in LH concentration. The cortisol concentrations in all ewes receiving either one or two injections of ACTH(1-24) were greater than 35 nmol/l at 10 h after the oestradiol injection. However, concentrations of progesterone increased from 0.9 +/- 0.3 (S.E.M.) nmol/l at the time of the second ACTH(1-24) injection to 2.1 +/- 0.3 nmol/l after 2 h.  aEwes  aPharmacology  aPhysiology  aPituitary hormones  aSheep  aEstradiol  aAnoestrus  aLH  aReleasing hormones1 aESSAWY, S. A.1 aALAM, M. G. S.  tJournal of Endocrinologygv. 118, n. 2, p.193-197, Aug. 1988.