Biomedical subjects

R L Matteri

Publications and source records attributed to R L Matteri.

57 records · Page 4Linked to original sources

PubMed1982

Effect of cortisol or adrenocorticotrophin on release of luteinizing hormone induced by luteinizing hormone releasing hormone in the dairy heifer.

During treatment with cortisol or ACTH, dairy heifers were given two doses of LH releasing hormone (LH-RH) spaced 1.5 h apart. Serum concentrations of cortisol and LH were monitored during each treatment. Treatment with both ACTH and cortisol raised plasma cortisol levels above the respective saline controls (P less than 0.001). Neither treatment affected basal LH concentrations. A slight depression in LH response was seen in the cortisol-treated animals after the first LH-RH injection, as shown by a statistically significant depression at three of the sample times. There was no significant difference between treated and control LH values after the second LH-RH administration. Treatment with ACTH resulted in significantly reduced LH values at all sample times after both injections of LH-RH.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

The effect of opioid peptides on ovine pituitary gonadotropin secretion in vitro.

Although a hypothalamic site of action has been firmly established for opiate-mediated gonadotropin regulation, there have been several reports which indicate the possibility of a direct influence on the pituitary gland. The objective of this study was to further investigate this possibility in an in vitro pituitary perifusion system utilizing ovine tissue. Treatment with gamma-endorphin (GE) or human beta-endorphin (hBE) resulted in elevated basal LH release (p less than 0.05), followed by an inhibition in the response to a subsequent GnRH challenge (p less than 0.05). The stimulatory effect of hBE was found to be dose-responsive (p less than 0.01). PRL secretion was not similarly stimulated. Ovine beta-endorphin (oBE) had no effect on LH secretion, even though it differs from hBE by only 2 amino acids and contains the active GE sequence. Met-enkephalin also did not influence gonadotropin secretion. Naloxone pretreatment did not reverse the effects of hBE on gonadotropin release. It was found, however, that [D-pGlu1, D-Phe2, D-Trp3,6]-GnRH, a specific GnRH receptor antagonist, did reduce hBE-induced LH and FSH release (p less than 0.05). Naloxone pretreatment alone suppressed the response to GnRH (p less than 0.05). These data indicate that certain opioid peptides can influence ovine gonadotropin secretion in vitro by activating the GnRH receptor. Furthermore, a facilitory role is suggested for endogenous opiates in the local regulation of pituitary gonadotropin secretion.

Animals↗

PubMedDate not supplied

Obesity affects circulating estradiol levels of premenopausal hirsute women receiving leuprolide acetate depot.

OBJECTIVE: To investigate the effect of premenopausal obesity on circulating levels of estradiol, estrone, free testosterone, androstenedione, DHEAS, and immuno- and bioactive FSH and LH. SETTING: University clinic. PATIENTS AND INTERVENTIONS: Premenopausal hirsute women, four obese and four nonobese, received leuprolide acetate depot [LD in monthly injections (7.5 mg, i.m.)] until estradiol levels decreased to menopausal values; single monthly injections of 15 and then 22.5 mg LD were given if estradiol remained higher than menopausal after 3 months. RESULTS: Estradiol levels of nonobese women reached menopausal values with the 7.5-mg dose, and those of obese women were not significantly reduced with any LD dose. Estrone declined to menopausal levels with 7.5 mg LD, while free testosterone and androstenedione were diminished with 7.5 mg, but not further with 15 or 22.5 mg. Bioactive LH and the bioactive/immunoactive LH ratio were maximally suppressed with 7.5 mg LD; however, LD did not change bioactive FSH levels or the bioactive/immunoactive FSH ratio. These findings were not related to adiposity. CONCLUSIONS: Premenopausal obesity affects circulating estradiol levels of hirsute women receiving LD. The effect does not reflect weight-related differences in circulating levels of androgens or bioactive gonadotropins. Premenopausal adiposity in hirsute women may influence the estrogenic milieu associated with desensitization to GnRH.

Adolescent↗