Suppression of gonadotropin secretion and prevention of ovulation in the rat by antiserum to synthetic gonadotropin-releasing hormone

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).…”

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

“…Passive immunoneutralization of luteinizing hormone-releasing hormone (LH-RH) prevents the preovulatory surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the rat (Koch, Chobsieng, Zor, Fridkin & Lindner, 1973;Arimura, Debeljuk & Schally, 1974;Kerdelhue, Catin, Kordon & Jutisz, 1976; Kawakami & Higuchi, 1979), hamster (de la Cruz, Arimura, de la Cruz & Schally, 1976) and ewe (Narayana & Dobson, 1979;Fraser & McNeilly, 1982). However, little is known about the changes associated with neutralization of LH-RH on tonic gonadotrophin secretion in the intact female.…”

The gene for the neuropeptide gonadotropin-releasing hormone is expressed in the mammary gland of lactating rats.

“…This peptide is synthesized and secreted from hypothalamic neurosecretory cells (7)(8)(9)(10), and when it reaches the pituitary gland, it induces the synthesis and secretion of follicle-stimulating hormone and luteinizing hormone (LH), which regulate gonadal functions (11). GnRH is also synthesized by the human placenta (12), T lymphocytes (13), and the rat ovary (14).…”