Effect of galanin on growth hormone (GH) response to thyrotropin releasing hormone of rat pituitary GH-secreting adenomatous cells (GH1) in culture.
The growth hormone (GH) releasing effect of thyrotropin-releasing hormone (TRH) and galanin, a 29-amino acid peptide widely distributed in mammalian CNS, alone or in combination was investigated in cultured rat pituitary tumor cells (GH1). TRH stimulated GH secretion in GH1 cells (maximal stimulation at the dose of 0.1 microM). Galanin alone had a significant GH inhibitory effect in GH1 cells at all the doses used. When the two peptides were administered in combination, no significant changes as compared to baseline levels were observed. The results of this study indicate that galanin has potent direct inhibitory effects on baseline and TRH-stimulated GH release from rat tumor cells.