Abstract
The role of growth hormone (GH) in stunting following head-irradiation in rodents and humans is unclear. We have reported no response to GH treatment in the stunted head-irradiated rat. Secretion profile of GH and cell size and number in brain, heart, liver, kidney and gastrocnemius muscle (gastroc) were determined in rats X-irradiated with 600 rads to the head only or sham-irradiated at 2 d of age. Blood was sampled for GH RIA from cannulated undisturbed rats at 15 min intervals for 18 h periods (9 h light and 9 h dark) at 47 to 64 d of age. Irradiated rats were significantly stunted in body weight and tail length. At 20-21 d of age they had significantly reduced weight of all organs; decreased brain organ/body ratio (p<0.0005) and total DNA (p<0.0005); increased DNA/organ in all organs, significant in heart (p<0.025) and gastroc (p<0.025); decreased protein/DNA in all organs, significant in brain (p<0.005), heart (p<0.01) and gastroc (p<0.05). Irradiated rats had normal rhythm of GH pulses; reduced numbers of GH values from 200 to 499 ng/ml (p<0.05) and 500 to 999 ng/ml (p<0.005), and reduced area under GH concentration vs time (p<0.025). We conclude that GH secretory rhythm is intact in the head-irradiated rat. Cell size and number results exclude neonatal hypopituitarism and/or undernutrition as causes of the growth stunting. Reduced GH secretion may thus only reflect setting of a putative centrally located growth regulator for a smaller body size.
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Mosier, H., Jansons, R., Swingle, K. et al. 473 GROWTH HORMONE AND STUNTED GROWTH FOLLOWING HEAD IRRADIATION. Pediatr Res 19, 189 (1985). https://doi.org/10.1203/00006450-198504000-00503
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DOI: https://doi.org/10.1203/00006450-198504000-00503