Growth hormone restores normal growth in selenium-treated rats without increase in circulating somatomedin C

Selenium intake (5.0 ppm) induces growth retardation, accumulation of selenium in somatotrophs, lack of growth hormone response to GHRH and an 80 per cent reduction in serum somatomedin C in infant rats. In addition, it induces a slight reduction in serum albumin and occasionally slight central liver necrosis. In order to determine the role of insufficient growth hormone production, the influence of exogenous growth hormone was studied during selenium intake in groups of rats during 25 to 46 days of age (post-weaning). A dosage of human growth hormone (100 micrograms twice daily) was chosen, this being sufficient to restore normal growth rate and normal serum somatomedin C in hypophysectomized rats of similar age. The weight gain in selenium-treated (3.3 ppm) rats was 46.0 +/- 11.7 g (SD)/21 days, whereas in selenium rats given growth hormone it was 66.6 +/- 8.9 g (P = 0.01), which was similar to the gain in control rats 72.3 +/- 6.9 g. The latter two were less than the weight gain in control rats given growth hormone: 91.5 +/- 11.5 g (P = 0.01 and P less than 0.01). Serum somatomedin C in untreated rats was 151 +/- 66 (SD) micrograms/l (25 days) increasing to 532 +/- 91 micrograms/l (34 days) and 482 +/- 64 micrograms/l (46 days). It did not increase above these levels in control rats given growth hormone. In selenium-treated rats, no increase occurred during growth hormone administration 138 +/- 148 micrograms/l (34 days) and 185 +/- 84 micrograms/l (46 days) (P less than 0.001 and P less than 0.001 vs untreated controls).(ABSTRACT TRUNCATED AT 250 WORDS)