Radioimmunoassay for Luteinizing Hormone Releasing Hormone in Plasma

Abstract

A sensitive and specific double antibody radioimmunoassay has been developed capable of measuring LH-RH in extracted human plasma. Thyrotropin releasing hormone, lysine vasopressin and most of LH-RH analogues did not appear to affect the assay. Hypothalamic extract and some of the LH-RH analogues produced displacement curves which were parallel to that obtained with the synthetic LH-RH. Sensitivity of the radioimmunoassay was about 3 pg per assay tube. The coefficient of variation of intraassay was 6.4%, while that of interassay was 9.6%. Exogenous LH-RH could be quantitatively extracted by acidic ethanol when varying amounts of synthetic LH-RH were added to plasma. Immunoreactivity of LH-RH was preserved in plasma until 2 hr in the cold and gradually reduced thereafter. The plasma levels in LH-RH were 20 pg/ml or less in normal adults and not detectable in children. The aged males over 60 yr and postmenopausal women showed a tendency to have higher levels of plasma LH-RH. Plasma LH-RH level was significantly higher in midcycle than in follicular and luteal stages. The disappearance rate of LH-RH from the circulation after intravenous injection could be represented as half times of 4-6 min. Between 0.2-0.4% of the injected dose was excreted into urine within 1 hr. These results indicate that the determination of LH-RH might be a useful tool for elucidating hypothalamic-pituitary-gonad interactions.

Effects of Gonadotropin-Releasing Hormone Agonist on the Incidence of Apoptosis in Porcine and Human Granulosa Cells

“…Testart et al [26,27] also reported that the total number of embryos was increased after GnRHa treatment but the proportion of good-quality embryos was reduced. Saito et al [28] investigated the plasma levels of buserelin in humans after an intranasal administration of 300 Ìg of buserelin.…”

Reevaluation of immunoreactive gonadotropin-releasing hormone(GnRH) levels in general circulation in women: Changes in levels and episodic patterns before, during and after gonadotropin surges.

“…Although circulatory GnRH has been measured by RIA, its levels and patterns in normal women have shown marked variations among individual studies (Aksel, 1979 and1981;Arimura et al, 1974;ElkindHirsch et al, 1982;Jonas et al, 1975;Jutisz and Kerdelhue, 1974;Miyake et al, 1980;Rosenblum and Schlaff, 1976;Saito et al, 1975;Tamada et al, 1973). Unextracted plasma contains potential interfering substances, which may be one of the reasons why high concentrations of immunoreactive GnRH have been reported in earlier studies (Arimura et al, 1974; Jeffcoate et al, 1974; Nett and Adams, 1977).…”

“…in order to elucidate the role of gonadotropin-releasing hormone (GnRH) in the control mechanism of gonadotropin release, particularly at mid-cycle in women, circulatory GnRH has been measured by radioimmunoassay (RIA) (Aksel, 1979 and1981;Arimura et al, 1974;Elkind-Hirsch et al, 1982;Jonas et al, 1975;Jutisz and Kerdelhue, 1974;Miyake et al, 1980;Rosenblum and Schlaff, 1976;Saito et al, 1975;Tamada et al, 1973). However, the levels and patterns of circulating GnRH obtained in earlier studies have not been consistent.…”

“…However, the levels and patterns of circulating GnRH obtained in earlier studies have not been consistent. Several investigators have insisted that there are significant elevations in circulatory GnRH levels during the periovulatory period of a menstrual cycle (Arimura et al, 1974;Elkind-Hirsch et al, 1982;Jutisz and Kerdelhue, 1974;Miyake et al, 1980;Rosenblum and Schlaff, 1976;Saito et al, 1975;Tamada et al, 1973). In contrast, these "mid -cycle" surges of GnRH have been denied by others (Aksel, 1979 and1981;Jonas et al, 1975).…”

Detection of Immunoreacting LH-RF Neurons in Rodents

“…"), this hormone has been widely utilized for many basic animal experiments in neuroendocrinology and has been used a clinical tool in differential diagnosis of pituitary and hypothalamic disorders. Furthermore, sensitive and specific radioimmunoassay for LH-RF have been developed in many loboratories2, 17,22,45,48). However, the sites of synthesis and release of this decapeptide in the hypothalamus have not been precisely identified, in part because of the lack of direct immunohistochemistry for LH-RF.…”