Pituitary response to growth hormone-releasing factor in rats with functional or anatomical lesions of the central nervous system that inhibit endogenous growth hormone secretion.
The pituitary growth hormone (GH) response to the growth hormone-releasing factor, hpGRF-44, was evaluated in male rats with various lesions of the central nervous system. These included an electrical lesion of the ventromedial hypothalamus, a chemical lesion of the arcuate nucleus induced by neonatal treatment with monosodium glutamate, a functional lesion of catecholamine synthesis with alpha-methyl-p-tyrosine or a functional lesion of catecholamine storage with reserpine. The first three lesions appear to partially inhibit normal somatostatin secretion since in every instance hpGRF-44 administration induced a significant increase in plasma GH concentrations. In contrast, reserpine blocked the GH response to hpGRF-44, presumably by stimulating somatostatin secretion. The pituitary GH response to hpGRF-44 in the above described models was enhanced by pretreatment of the rats with antibodies against somatostatin. The pituitary GH response to repeated injections of hpGRF-44 was also evaluated in rats with an anatomical lesion of the arcuate nucleus or a functional lesion of catecholamine synthesis. The maximum GH response did not vary over time to the repeated injections of hpGRF-44 in rats with lesions of the arcuate nucleus; however, interruption of catecholamine synthesis resulted in a significant decrease in the GH response to hpGRF-44 over time.
D000818:Animals; D000906:Antibodies / Q000008:administration & dosage; D001111:Arcuate Nucleus of Hypothalamus / Q000502:physiology; D002395:Catecholamines / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012110:Reserpine / Q000494:pharmacology; D013004:Somatostatin / Q000276:immunology / Q000378:metabolism; D014697:Ventromedial Hypothalamic Nucleus / Q000502:physiology
D000906:Antibodies; D002395:Catecholamines; D010446:Peptide Fragments; D013004:Somatostatin; D012110:Reserpine; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone