Increase in mRNA Concentrations of Pituitary Receptors for Growth Hormone-Releasing Hormone and Growth Hormone Secretagogues After Neonatal Monosodium Glutamate Treatment

Autor: Béla Flerkó, Magdolna Kovacs, Rhonda D. Kineman, Andrew V. Schally, Lawrence A. Frohman
Rok vydání: 2001
Předmět:
Zdroj: Journal of Neuroendocrinology. 12:335-341
ISSN: 1365-2826
0953-8194
Popis: Previous studies have demonstrated that neonatal monosodium glutamate (MSG) treatment destroys growth hormone releasing-hormone (GHRH) neurones within the hypothalamic arcuate nucleus, decreases serum GH and insulin-like growth factor (IGF-I) concentrations, and retards linear growth. In the present study we investigated whether expression of pituitary GH, GHRH receptors (GHRH-R), growth hormone secretagogue receptors (GHS-R) and liver IGF-I is altered in this model of GHRH deficiency. In addition, we investigated if treatment of MSG-lesioned rats with the GHRH agonist, JI-38, would 'normalise' the GH-axis. Serum GH and IGF-I concentrations were determined by RIA, GH mRNA levels were evaluated by Northern blotting, and GHRH-R, GHS-R and IGF-I mRNA levels were measured by semiquantitative RT-PCR. In accord with previous reports, neonatal MSG treatment caused 50% and 76% decreases in serum GH and IGF-I concentrations, respectively, at 8 weeks of age. The decline in circulating GH was accompanied by a 56% reduction in total pituitary GH content, which was a reflection of the decrease in total pituitary protein. However, GH concentration (per mg protein) was unaltered. Despite the maintenance of a normal GH concentration, GH mRNA concentration (per microg total RNA) was suppressed by 42%, compared to saline-treated controls (P
Databáze: OpenAIRE
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