THE CELL-POPULATION OF SOMATOSTATIN AND GROWTH HORMONE-RELEASING FACTOR USING QUANTITATIVE IMMUNOHISTOCHEMISTRY IN THE ISOLATED GH DEFICIENT DWARF RAT

We examined the cell population of somatostatin (SS) in the periventricular nucleus (PN) and growth hormone-releasing factor (GRF) in the arcuate nucleus (ARC) between spontaneous dwarf rats (SDRs; gene symbol: dr), which show isolated GH deficiency, and normal rats using avidin-biotin complex (ABC) immunohistochemistry. The total number of SS perikarya per brain weight in the PN of SDRs was 824.8 ± 49.6 (mean ± S.E.M., n = 4), whereas that of controls was 1108.5 ± 50.1 (n = 4). The GRF perikarya per brain weight in the ARC of SDRs numbered 1281.0 ± 26.0 (n = 7), as compared to 685.4 ± 64.6 (n = 7) in the controls. The SS perikarya in the PN of SDRs were significantly reduced (P < 0.05), while the GRF perikarya in the SDRs were significantly increased (P < 0.01). These results suggest that GH itself acts on SS to positively regulate its secretion and on GRF in a negative regulatory manner. © 1990.