Significant Increase In Plasma Growth Hormone Research Articles

Effects of environmental osmolality on release of prolactin, growth hormone and ACTH from the tilapia pituitary

Prolactin (PRL) plays a central role in freshwater (FW) adaptation in teleost fish. Evidence now suggests that growth hormone (GH) acts in the seawater (SW) adaptation in at least some euryhaline fish. Reflecting its important role in FW adaptation, plasma levels of PRL 188 and PRL 177 are higher in tilapia ( Oreochromis mossambicus) adapted to FW than in those adapted to SW. A transient but significant increase in plasma GH was observed 6 h after transfer from FW to SW. Elevated plasma PRL levels were seen in association with reductions in plasma osmolality after blood withdrawal in FW fish whereas no significant change was seen in plasma GH levels. When pituitaries from FW tilapia were incubated for 7 days, secretion of both PRLs was significantly greater in hyposmotic medium than in hyperosmotic medium for the first 24 h. Secretion of GH from the same pituitary was relatively low during this period compared with PRL secretion. No consistent effect of medium osmolality on GH release was seen for the first day, but its cumulative release was increased significantly in hyperosmotic medium after 2 days and thereafter. On the other hand, ACTH release was extremely low compared with the secretion of PRLs and GH and there was no consistent effect of medium osmolality. These results indicate that PRL release from the tilapia pituitary is stimulated both in vivo and in vitro as extracellular osmolality is reduced, whereas the secretion of GH increases temporarily when osmolality is increased. ACTH seems to be relatively insensitive to the changes in environmental osmolality.

Effects of galanin on growtn hormone and prolactin secretion in anorexia nervosa

Galanin (GAL) elicits growth hormone (GH) release in normal subjects through interaction with hypothalamic somatostatin. GAL also stimulates GH-releasing hormone (GHRH) secretion in vitro. In rats, GAL is able to stimulate prolactin (PRL) release, but this effect is not clear in humans. We have thus investigated GAL effects on GH and PRL release in patients with anorexia nervosa (AN), known to have altered regulation of the GH-insulin-like growth factor axis and PRL dynamics, and compared the effects of GHRH and GAL on GH and PRL secretion in AN and normal healthy subjects. Eight women with AN (15 to 27 years; body mass index [BMI], 17 to 19.5 kg/m2) were treated with (1) GHRH 50 microg intravenous (IV) injection, (2) porcine GAL 500 microg infusion from -10 to +30 minutes, and (3) 135-minutes saline infusion as a control, respectively. Both peptides induced a significant increase in plasma GH in AN patients (peak level, 27.41 +/- 5.50 microg/L after GAL and 18.97 +/- 2.67 microg/L after GHRH). When data for AN patients and the control group were compared, GH peak levels after GAL were significantly higher in AN patients (27.41 +/- 5.50 v 13.64 +/- 2.32 microg/L), while GH peak levels after GHRH were not different between the 2 groups (18.97 +/- 2.67 v 15.98 +/- 3.88 microg/L). PRL levels significantly increased after both GHRH (peak, 11.70 +/- 2.80 microg/L) and GAL (peak, 18.02 +/- 5.10 microg/L) treatment in AN patients, but not in normal subjects. We conclude that GAL stimulates exaggerated GH release in AN patients as compared with normal controls, suggesting a dual hypothalamic interaction via both an increase in endogenous GHRH and a decrease in somatostatin secretion. Finally, GAL may act as a PRL secretagogue in AN patients.

Neuroendocrine evidence for dopaminergic actions of hypericum extract (LI 160) in healthy volunteers

Background: We studied the effect of a single dose of a formulation of a methanolic extract of Hypericum perforatum (HP), also known as St. John’s wort, on plasma concentrations of growth hormone (GH), prolactin (PRL), and cortisol (CORT) in 12 healthy male volunteers.Methods: Subjects received 9 tablets of the finished product Jarsin®300 and placebo in a double-blind, balanced-order, cross-over design.Results: Following HP relative to placebo, there was a significant increase in plasma GH and a significant decrease in plasma PRL. Plasma CORT levels were unchanged.Conclusions: Taken together with data from animal experimental studies, the findings suggest that this dose of HP may increase some aspects of brain dopamine function in humans.

シバヤギの成長ホルモン放出に及ぼすペントバルビタールの効果

The effect of intravenous (iv) injection of pentobarbital sodium (PB) on plasma concentration of growth hormone (GH) in the Japanese Shiba goats was studied. An acute significant increase in plasma GH was observed in the goats after a single PB injection of 19mg/kg BW. Plasma GH concentration remained unchanged after injection of vehicle or 10mg/kg BW PB in the goats. The present results suggested that anesthetic dose of PB induced a release of GH in the Shiba goats.

Discordance between growth hormone (GH) responses after GH-releasing hormone and insulin hypoglycemia in myotonic dystrophy.

Plasma GH responses to human GHRH, arginine, L-dopa, and insulin-induced hypoglycemia were determined in seven myotonic dystrophy (MD) patients. An iv bolus injection of GHRH-(1-44)-NH2 (1 microgram/kg BW) only slightly increased plasma GH concentrations in MD patients. The mean peak plasma GH level after GHRH injection [4.2 +/- 0.8 (+/- SE) micrograms/L] was significantly lower than that in 10 age-matched normal subjects (26.7 +/- 4.3 micrograms/L) or that in 6 patients with progressive muscular dystrophy (22.8 +/- 6.6 micrograms/L) whose nutritional status was similar to that of the MD patients. Even with a larger dose of GHRH (3 micrograms/kg BW), the plasma GH rises were minimal in the MD patients (mean peak, 5.9 +/- 1.8 micrograms/L). The plasma GH responses to a 30-min iv infusion of arginine (0.5 g/kg BW) and oral ingestion of L-dopa (0.5 g) were attenuated to a similar extent, whereas insulin-induced hypoglycemia caused a significant increase in plasma GH in all seven MD patients [mean peak, 17.4 +/- 4.1 (+/- SE) microgram/L]. The plasma TSH responses to TRH and plasma insulin-like growth factor I levels were similar in the MD patients and normal subjects. These findings suggest that 1) the impaired GH release after GHRH, arginine, and L-dopa administration in MD patients is not due to somatotroph deficiency, since the GH response to hypoglycemia is well preserved; and 2) insulin-induced hypoglycemia may stimulate GH release at least in part via inhibition of somatostatin release.

Evidence for a role of delta sleep-inducing peptide in slow-wave sleep and sleep-related growth hormone release in the rat.

To examine the role of delta sleep-inducing peptide (DSIP) in sleep-related growth hormone (GH) release, male rats were deprived of sleep for 4 hr by placing them on a slowly rotating wheel. Sleep deprivation by this method caused a significant increase in GH release, as indicated by the increase in plasma GH concentrations (P less than 0.01), and also in the amount of slow-wave sleep (SWS) (P less than 0.001) above initial values after removal of the animals from the rotating wheel. These increases were blocked by microinjection into the third cerebral ventricle of highly specific antiserum to DSIP. In control rats receiving an equal volume of normal rabbit serum, the significant increase in plasma GH as well as SWS remained after removal of the rats from the wheel. The increased release of endogenous DSIP in the sleep-deprived animals may have caused an increase in SWS as well as plasma GH. Since DSIP increases plasma GH after its injection into the third cerebral ventricle and since passive immunization against DSIP blocks the increase in SWS and GH release that follows the 4 hr of sleep deprivation, the results suggest that DSIP can be a physiological stimulus for sleep-related GH release as well as for the induction of SWS.

Idiopathic growth hormone (GH) deficiency, and GH deficiency secondary to hypothalamic germinoma: effect of single and repeated administration of human GH-releasing factor (hGRF) on plasma GH level and endogenous hGRF-like immunoreactivity level in cerebrospinal fluid.

Plasma GH responses to iv administered synthetic human GH-releasing factor-(1-44)-NH2 (hGRF) and the concentration of endogenous hGRF-like immunoreactivity (hGRF-LI) in the cerebrospinal fluid (CSF) were examined in 16 children with GH deficiency (GHD). Ten patients had idiopathic GHD, and six had GHD secondary to germinoma. An iv bolus hGRF (1 microgram/kg BW) injection test was performed the day before and the day after treatment, with a daily 1-h iv infusion of hGRF (2 micrograms/kg BW) for 3 days. Plasma GH increases (greater than 5 ng/ml) after the first iv bolus injection of hGRF occurred in 2 of the 10 idiopathic GHD children and in 4 of the 6 GHD patients with germinoma whereas the first bolus hGRF injection failed to elicit GH release in the remaining 10 patients. The mean +/- SEM peak plasma GH level after the first bolus hGRF dose in the patients with germinoma (8.2 +/- 2.2 ng/ml) was significantly higher than that in the idiopathic GHD patients (2.9 +/- 0.9 ng/ml; P less than 0.05), but significantly lower than that in normal children with short stature (18.5 +/- 2.5 ng/ml; P less than 0.05). In the 2 patients with germinoma and in 5 of the 8 idiopathic GHD children who did not respond to the first hGRF bolus dose, a significant plasma GH response to hGRF occurred during a daily iv infusion of hGRF for 3 consecutive days, whereas the remaining 3 idiopathic GHD children failed to respond to the daily hGRF infusions. The plasma GH response after the second hGRF bolus dose given after treatment with daily hGRF infusions for 3 days was not different from that after the first hGRF bolus in patients with germinoma or that in the idiopathic GHD children. hGRF-LI was not detected (less than 5.8 pg/ml) in the CSF in any of 5 patients with germinoma, whereas it was present in 5 idiopathic GHD patients (mean, 17.5 +/- 0.9 pg/ml), 3 of whom were nonresponders to daily hGRF infusions. From these results, GHD secondary to destruction of hypothalamic GRF neurons might be defined by the following findings: 1) lack of a GH response to the standard provocative tests acting through the hypothalamus; 2) significant increase in plasma GH after a single bolus and/or repetitive iv administration of hGRF; and 3) undetectable or extremely low levels of endogenous hGRF-LI in the CSF. Most of the idiopathic GHD patients responded to the repetitive hGRF infusion, suggesting insufficient secretion of hypothalamic hGRF as the primary defect. However, since hGRF-LI was detectable in the CSF in some of the idiopathic GHD patients, its pathogenesis must be multifactorial.

Growth hormone (GH) release following thyrotropin-releasing hormone (TRH) injection in manic patients receiving lithium carbonate

(1) The effect of intravenous injection of synthetic TRH (500 μg) on the plasma GH was investigated in six patients in the manic state and five normal volunteers, both before and during lithium treatment, for 3–4 weeks. (2) TRH caused a significant increase in plasma GH in four out of six manic patients during lithium treatment. (3) TRH only raised plasma GH in one patient before lithium treatment. (4) No appreciable change was noted in normal subjects either before or during lithium treatment. (5) The positive GH responses to TRH in manic patients on lithium were observed 90–120 min after TRH except for one patient. (6) The delayed GH response may be caused by secondary effects of TRH on brain monoamine neurotransmitters, rather than by a direct action of TRH on the pituitary.

Elevated Basal Growth Hormone Levels and Growth Hormone Response to TRH in Alcoholic Patients with Cirrhosis

Basal plasma growth hormone (GH) and GH responses after the administration of thyrotropin releasing hormone (TRH) were studied in 9 male alcoholic patients with cirrhosis. Basal GH was significantly higher in cirrhotic patients than in normal men. Intravenous injection of synthetic TRH (400 microgram) caused a significant increase in plasma GH in 7 out of the 9 cirrhotic patients examined, while it did not increase GH levels in normal subjects.

Growth hormone release by gamma-aminobutyric acid (GABA) and gamma-amino-beta-hydroxybutyric acid (GABOB) in the rat.

Effects of gamma-aminobutyric acid (GABA) and gamma-amino-beta-hydroxybutyric acid (GABOB) on growth hormone (GH) release were investigated in the urethaneanesthetized male rat. An intraventricular injection of GABA and L-GABOB but not D-GABOB caused a significant increase in plasma GH. An intravenous injection of L-GABOB, at the dose which had no significant effect on basal plasma GH, remarkably enhanced plasma GH response to pentobarbital. These results suggest that GABA and L-GABOB stimulate GH release possibly via the central nervous system in the rat.

Plasma growth hormone, insulin, and glucagon responses to arginine infusion in children and adolescents with idiopathic short stature, isolated growth hormone deficiency, panhypopituitarism, and anorexia nervosa.

The effects of intravenous infusion of arginine (20 g/m2) after an overnight fast on plasma immunoreactive growth hormone (GH), insulin (IRI), and glucagon (IRG), and blood glucose were examined in five groups of children and adolescents: 10 normal individuals, 18 with idiopathic short stature, 6 with isolated growth hormone deficiency, 8 with panhypopituitarism, and 6 with anorexia nervosa. The mean fasting plasma GH concentration was significantly elevated in the group with anorexia nervosa (P less than 0.05), and similar to the value for the normal group in all other groups. After arginine infusion, four- to sixfold increases of plasma GH were observed in the normal children, and similar increases were seen in those with idiopathic short stature as well as in those with anorexia nervosa; whereas, in the children with isolated growth hormone deficiency or panhypopituitarism, there was no significant increase in plasma GH. Fasting blood glucose concentrations were significantly lower than normal in subjects with isolated growth hormone deficiency (P less than 0.05), panhypopituitarism (P less than 0.001), and anorexia nervosa (P less than 0.001), whereas fasting plasma IRI and IRG concentrations were similar to the values in the normal group. Plasma IRI increased eightfold at the end of the 30-min arginine infusion in the normal subjects; the increase was slightly but not significantly less in those with idiopathic short stature, and significantly less in those with isolated growth hormone deficiency (P less than 0.05), panhypopituitarism (P less than 0.001), and anorexia nervosa (P less than 0.05). Arginine infusion resulted in two- to threefold increases of plasma IRG in the normal group, and similar increases were observed in all of the other groups tested. These results suggest that whereas pancreatic beta cell responsiveness may be deficient in children and adolescents with isolated growth hormone deficiency, panhypopituitarism, or anorexia nervosa, pancreatic alpha cell responsiveness, to arginine at least, appears to be intact under these conditions.

Growth hormone and prolactin release after injection of thyrotropin-releasing hormone in patients with depression.

The effects of thyrotropin-releasing hormone (TRH) on the release of growth hormone (GH), prolactin (PRL) and thyrotropin (TSH) were investigated in patients with depression. Intravenous injection of synthetic TRH (500 mug) caused a significant increase in plasma GH (peak value: 7.7 minus 35.0 ng/ml) in 8 of 13 patients with mental depression. After clinical recovery these patients had no response of plasma GH to TRH. TRH administration did not raise plasma GH in normal subjects examined. Plasma PRL responses to TRH were significantly enchanced (P smaller than 0.05) in depressed patients compared with control subjects. Plasma TSH responses to TRH were significantly blunted in patients with depression (P smaller than 0.05). These results suggest disorders in the hypothalamo-pituitary function in depression.

Comparison with growth hormone responses to various drugs or substances in patients with active acromegaly (author's transl)

Growth hormone (GH) responses to L-dopa, 2-Br-alpha-ergocryptine (CB-154), thyrotropine-releasing hormone (TRH), luteinizing hormone-releasing hormone (LH-RH), glucagon and glucose were investigated in six patients with active acromegaly. The following results were obtained. 1) Subcutaneous injection of 1 mg glucagon caused a clear-cut decrease in plasma GH levels in 5 out of 6 active acromegalic patients at 30 minutes after the injection. In 2 out of 6 patients a rebound of plasma GH was observed. 2) In three out of six patients with active acromegaly, oral administration of 0.5 g L-dopa caused a significant suppression of plasma GH levels. 3) CB-154 (2.5mg) administered orally elicited a marked decrease in plasma GH levels in the same three patients who showed a significant suppressive GH reponse to L-dopa, and the inhibitory effect of CB-154 on GH secretion lasted for 6 hours. These patients who had a GH response to L-dopa or CB-154 were named "responders". 4) Intravenous administration of TRH resulted in a significant increase in plasma GH in 4 patients 3 of whom were responders and the other a non-responder. 5) Pretreatment with CB-154 did not modify the TRH-induced GH increase in all patients who had a positive response to TRH. 6) A significant increase in plasma GH was elicited by the intravenous injection of 100 mug LH-RH in 3 out of 6 patients with acromegaly. 7) When oral administration of CB-154 had been given 2 hours before LH-RH, the GH response to LH-RH was blunted in two of three patients who had a LH-RH-induced increase in plasma GH levels.

Effect of vasotocin and glucagon on plasma growth hormone levels in the pigeon

1. 1. Injection of vasotocin did not have a significant effect on the plasma growth hormone (GH) level in the pigeon, at 15 or 30 min post-injection, when compared with isotonic saline injection. 2. 2. GH levels at 30 min post-injection of vasotocin as well as of saline were significantly higher than the respective levels at 15 min post-injection. 3. 3. Glucagon produced an elevation in plasma GH at 5 min post-injection. 4. 4. Injection of vasotocin 5 min after the glucagon injection produced a further significant increase in plasma GH when tested 15 min after the vasotocin injection (i.e. 20 min after glucagon injection). No such increase was noticed when saline alone was injected instead of vasotocin. 5. 5. A synergistic effect of glucagon and vasotocin on plasma GH level has been suggested.