The Effect of Luteinizing Hormone Releasing Hormone (LHRH) Antiserum Administrationon Gonadotropin Secretion in the Rhesus Monkey¹²

Abstract

Single iv injections of a rabbit antiserum to synthetic LHRH promptly suppressed serum LH and FSH concentrations in ovariectomized rhesus monkeys. Gonadotropin levels remained depressed for 10-21 days, the approximate duration of enhanced LHRH binding activity in the circulation. Doses of LHRH antiserum sufficient to reduce tonic gonadotropin secretion did not modify the time course or magnitude of estrogen-induced gonadotropin surges. These negative findings, however, cannot be interpreted to signify that such surges are not caused by a release of LHRH.

Decreased release of gonadotropin-releasing hormone during the preovulatory midcycle luteinizing hormone surge in normal women.

“…This finding is supported by earlier observations in rhesus monkeys that GnRH antisera do not block sex steroid-induced gonadotropin surges (29) and that a gonadotropin surge can be generated in response to estrogen in the absence of GnRH for up to 24 hr (30). However, recent studies in rhesus monkeys indicate that GnRH levels are increased in both spontaneous and steroid-induced gonadotropin surges (8,9).…”

Differential effects of LH-RH immunoneutralization on LH and FSH secretion in the ewe

“…In the male rat, serum FSH values did decline 24 h after LH-RH antibody administration, but the fall was slower and less pronounced than for LH (Fraser, Sharpe, Lincoln & Harmer, 1982). Also, in the ovariectomized rat, rhesus monkey and ferret treated with LH-RH antibodies, FSH concentrations decline more slowly than do those of LH (Koch et ai, 1973;McCormack, Plant, Hess & Knobil, 1977;Gledhill, Fraser & Donovan, 1982 (Lincoln, 1979). In the present study we consider the most important influence on the pattern of FSH observed to be the changes in the levels of ovarian factors which feedback on the pituitary gonadotrophs.…”

Effect of oestrogen and an LH-RH agonist on the release of gonadotrophins in ovariectomized ewes deprived of LH-RH

“…The presence of small amounts of biologically active LH-RH may also explain why some FSH is detectable in the plasma of LH-RH immunized ewes. Nevertheless, in these ewes the action of LH-RH is effectively blocked and as the source of the ovarian steroid hormones is also absent they provide an in-vivo system with which to study the ability of oestrogen and LH-RH agonists to stimulate the secretion of LH (Fraser & Sandow, 1977;Clarke et al, 1978;Jeffcoate et al, 1978 (Koch et al, 1973), hamster (de la Cruz et al, 1976) and fowl (Fraser & Sharp, 1978), but are in marked contrast to the lack of effect in the rhesus monkey, in which administration of antibodies both before and after oestrogen injection failed to abolish the LH surge (McCormack et al, 1977).…”

“…Injection of LH-RH antiserum to rats and hamsters at 12:00 h on the day of pro-oestrus prevents the peovulatory LH surge (Koch, Chobsieng, Zor, Fridkin & Lindner, 1973;de la Cruz, Arimura, de la Cruz & Schally, 1976), and to chickens blocks the progesterone-induced LH surge (Fraser & Sharp, 1978). In marked contrast, LH-RH antiserum was without effect on the oestrogen-induced LH surge in the rhesus monkey (McCormack, Plant, Hess & Knobil, 1977). Active immunization against LH-RH prevents ovulation in the rat (Fraser & Baker, 1978), sheep (Clarke, Fraser & McNeilly, 1978;Jeffcoate, Foster & Crighton, 1978), marmoset monkey (Hodges & Hearn, 1977) (Fraser & Sandow, 1977) and sheep (Clarke et al, 1978) immunized against LH-RH.…”