Growth Hormone Response Curve Research Articles

Growth hormone response of steers injected with synthetic human pancreatic growth hormone-releasing factors.

Four Holstein steers (312 kg) in a 4 X 4 Latin-square design were injected iv with 0, 100, 300 and 1,000 micrograms of a 44 amino acid growth hormone-releasing factor, hpGRF-44 NH2 in Exp. 1. Blood was collected at 20-min intervals from -1 to +6 h. All doses of hpGRF-44 NH2 stimulated an increase in serum growth hormone (GH) concentrations, whereas prolactin and luteinizing hormone concentrations were unaffected. Steers injected with the 1,000-micrograms dose appeared to have a biphasic release of GH that was not observed at the other doses. Amplitude of the GH peak after the 1,000-micrograms dose tended to be higher (P less than .15) than the peak caused by either the 300-micrograms or 100-micrograms dose, and the latter two were similar. Area under the GH response curve increased (P less than .05) with increasing doses of hpGRF-44 NH2. Endogenous episodic secretion of GH resumed within 6 h after injection of 100 micrograms hpGRF-44 NH2, but not after either the 300-micrograms or 1,000-micrograms dose. In Exp. 2, six Holstein steers (352 kg) in a 6 X 6 Latin-square design received an iv injection of 0, 10, 25, 50 and 100 micrograms hpGRF-44 NH2 and 100 micrograms hpGRF-40 OH. Blood was collected at 20-min intervals from -1 to +4 h, with additional samples at 5, 10 and 15 min. Four of six steers responded to 10 micrograms hpGRF-44 NH2, but all of the steers responded to all other doses of hpGRF-44 NH2 and to hpGRF-40 OH.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth hormone, glucocorticoid and thyroxine response to duration, intensity and wavelength of light in prepubertal bulls.

Effects of duration, intensity and wavelength of light on growth hormone (GH), glucocorticoids, thyrotropin (TSH) and thyroxine (T4) concentrations in serum were determined in prepubertal bulls maintained at 18 to 22 C and 60 tp 70% relative humidity. Mean GH was 8.3 +/- .8, 9.5 +/- 2.2 and 13.8 +/- 2.2 ng/ml (P greater than .10) during 6 weeks of exposure to 8 hr of light: 16 hr of dark (8L:16D), 16L:8D and 20L:4D, respectively. However, concentrations of GH were more variable (P less than .01) in bulle exposed to 16L:8D and 20L:4D than in bulls exposed to 8L:16D. Concentrations of GH averaged 10.6 +/- 1.3 and 13.6 +/- 2.6 ng/ml (P greater than .10) when intensities of light exposures were 22 and 540 lux. Variability of GH was greater (P less than .01) in bulls exposed to 540 lux. Increase in the duration of light by the addition of 8 hr of red (550 to 750 nm) or 8 of blue (300 to 427 nm) light to 8 hr of white (300 to 750 nm) light did not affect (P greater than .10) mean GH concentrations. Among experiments, concentrations of glucocorticoids decreased by 29 to 58% (P less than .05) when daily light exposures were increased from 8 to 15.7, 16 or 20 hours. Conversely, glucocorticoids increased by 118% (P less than .05) when light was decreased from 15.7 to 8 hr daily. Duration of light exposures did not effect concentrations of TSH or T4. Similarly, intensities of 22 and 540 lux and blue and red wavelengths of light did not affect average concentrations of glucocorticoids or T4. Injection of 33 microgram thyrotropin releasing hormone (TRH)/100 kg body weight increased (P less than .05) GH two- to five-fold above average basal values; however, duration, intensity and wavelength of light did not influence peak GH concentration or area of GH response curves after injection of TRH. We conclude that in comparison with 8 L, 16 L increased variance of GH without affecting average concentrations of GH, TSH or T4. In contrast, 16 L suppressed serum glococorticoids.

Metabolic and endocrine alterations in osteosarcoma patients

Eighteen patients with primary osteosarcoma were studied for abnormal endocrinologic functions. Oral glucose tolerance tests revealed abnormal glucose, insulin, or growth hormone response curves in 78% of the study population. Elevated somatomedin values were noted in 72% of the patients tested. No significant deviations were observed in serum cortisol, estradiol, testosterone, follicle stimulating hormone, and luteinizing hormone levels. Likewise, lipid screening and 24 hour 17-hydroxy and 17-keto steroid excretion levels were normal. Statistically these derangements were unrelated, leading to the hypothesis that some additional factor or factors are present and responsible for the abnormalities noted. These deviations, found in association with primary osteosarcoma, constitute a new "paraneoplastic syndrome."