Examination of a possible mechanism by which anisomycin suppresses pulsatile luteinizing hormone release in ovariectomized rats.
An initial study was performed to ascertain the effects of anisomycin, a reversible inhibitor of protein synthesis, on pulsatile luteinizing hormone (LH) release in adult, ovarietomized (OVX) rats. For this experiment, rats OVX 3-4 weeks earlier were fitted with indwelling atrial cannulae. On the next day (approximately 13.00 h), the rats received a subcutaneous injection of either 100 mg/kg body weight (BW) anisomycin or its saline vehicle. Administration of anisomycin significantly suppressed mean plasma LH levels, mean trough values, and both LH pulse frequency (saline: 6.3 pulses/3 h vs. anisomycin: 2.7 pulses/3 h) and amplitude. To determine whether anisomycin affected anterior pituitary LH responses to LH-releasing hormone (LHRH), a second experiment was performed in which saline- and anisomycin-treated OVX rats were given an intravenous injection of 10 ng/100 g BW LHRH 1.5 h later (14.30 h). Rats then were sacrificed and the anterior pituitary and brain removed. Whereas preinjection plasma LH levels were significantly lower in anisomycin-treated rats, they were significantly higher in anisomycin-treated rats 20 min after LHRH. Consequently, mean maximal increments and percent increments were significantly higher in anisomycin-treated rats. AP LH content and content of LHRH in the medial preoptic and suprachiasmatic nuclei were not influenced by anisomycin treatment. However, median eminence (ME) LHRH concentrations in anisomycin-treated rats were almost double the LHRH levels measured in control rats. A third study was conducted to assess the effects of anisomycin on basal and potassium (K+)-stimulated LHRH release from superfused ME explants.(ABSTRACT TRUNCATED AT 250 WORDS)
DePaolo
L V
LV
Department of Physiology, University of Texas Health Science Center, San Antonio.
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology*; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007031:Hypothalamus / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism*; D008473:Median Eminence / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D010052:Ovariectomy; D011188:Potassium / Q000494:pharmacology; D011301:Preoptic Area / Q000378:metabolism; D011759:Pyrrolidines / Q000494:pharmacology*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology
D009419:Nerve Tissue Proteins; D011759:Pyrrolidines; D012701:Serotonin; D007987:Gonadotropin-Releasing Hormone; D000841:Anisomycin; D007986:Luteinizing Hormone; D011188:Potassium; D004298:Dopamine; D009638:Norepinephrine