Growth hormone secretion in old female rats analyzed by the reverse hemolytic plaque assay

1992 ◽  
Vol 127 (6) ◽  
pp. 531-535 ◽  
Author(s):  
Sumio Takahashi
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Plaque Assay ◽  
Growth Hormone Secretion ◽  
Young Female ◽  
Female Rats ◽  
Plaque Area ◽  
Gh Cells ◽  
Reverse Hemolytic Plaque Assay ◽  
The Mean

Growth hormone (GH) release was studied in young (3–4-month-old) and old persistent diestrous (20– 21-month-old) female rats using the reverse hemolytic plaque assay. A bimodal distribution of reverse hemolytic plaque area was observed in both young and old female rats. The mean and median of the plaque area of GH cells from old females were smaller than those from young female rats. The percentage of plaque-forming GH cells in old female rats was lower than in young female rats. The percentage of large plaque-forming GH cells (plaque area, more than 8 × 103 μm2) was lower in old female rats than in young female rats. GH-releasing hormone (GHRH) increased the mean and median of plaque areas in both young and old female rats. However, responsiveness to GHRH was reduced in old female rats. These results indicate that the amount of GH released from individual GH cells decreases with age in female rats, resulting in diminished GH secretion.

Sex-related differences in GH secretion in rat using reverse hemolytic plaque assay

1986 ◽  
Vol 250 (6) ◽  
pp. E650-E654
Author(s):  
K. Y. Ho ◽  
D. A. Leong ◽  
Y. N. Sinha ◽  
M. L. Johnson ◽  
W. S. Evans ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Time Course ◽  
Hormone Secretion ◽  
Plaque Assay ◽  
Secretory Response ◽  
Female Rats ◽  
Pituitary Cells ◽  
Gh Secretion ◽  
Plaque Area ◽  
Secretory Capacity

It is not known whether enhanced growth hormone (GH)-releasing factor (GRF)-stimulated GH release observed in the male reflects differences in somatotrope numbers and/or secretory response to GRF. We addressed this question by using the hemolytic plaque assay which allows quantification of hormone secretion by single pituitary cells. Time-course studies and GRF-GH concentration-response relationships (0.01, 0.1, 1, 10, 100, 1,000 nM GRF) in age-matched male and diestrous day 2 female rats were compared by quantitating the percent of GH plaque-forming cells, and measuring the plaque areas. The male pituitary contained a greater percent (P less than 0.05) of somatotropes (% of plaque-forming cells 45 +/- 2 vs. 27 +/- 4% in the female; mean +/- SE). GRF induced a greater concentration-dependent increase in plaque areas in the male. Maximal responses were attained at 10 nM GRF in both sexes. However, mean maximal plaque area was significantly greater (P less than 0.001) and the EC50 was significantly lower (P less than 0.05) in the male (0.25 +/- 0.09 vs. 1.78 +/- 0.64 nM in the female). The data suggest that the greater percent of somatotropes in the male and greater secretory capacity and sensitivity to GRF may contribute to sex-related differences in GH secretion in the rat.

DIFFERENT EFFECTS OF EXOGENOUS CYCLIC ADENOSINE MONOPHOSPHATE AND ITS DIBUTYRYL DERIVATIVE ON PLASMA GROWTH HORMONE, GLUCOSE, INSULIN AND CORTISOL

1976 ◽  
Vol 83 (1) ◽  
pp. 15-25
Author(s):  
M. Vanderschueren-Lodeweyckx ◽  
W. Proesmans ◽  
E. Eggermont ◽  
R. Eeckels
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Normal Subjects ◽  
Immunoreactive Insulin ◽  
Plasma Growth Hormone ◽  
Hormone Levels ◽  
The Mean

ABSTRACT The effects of the infusion in four different dosages (0.001, 0.005, 0.02 and 0.2 mg/kg/min during 60 min) of cyclic 3′,5′-adenosine monophosphate and of its dibutyryl derivative on plasma growth hormone and on glucose, immunoreactive insulin and cortisol were studied in 38 normal subjects and in 10 patients with idiopathic hypopituitarism. In normal subjects cyclic 3′,5′-adenosine monophosphate provokes an increase in plasma growth hormone levels (only when a dosage of 0.2 mg/kg/min is used) without any changes in plasma glucose, insulin and cortisol. The maximal value of the means is observed 75 min after starting the infusion. Dibutyryl cyclic 3′,5′-adenosine monophosphate (0.2 and 0.02 mg/kg/min) provokes a dose-related rise in plasma growth hormone levels which is always preceded by hyperglycaemia and hyperinsulinaemia. The peak of the mean growth hormone levels occurs at 135 min after initiation of the infusion. In all but one hypopituitary patients the nucleotides do not promote growth hormone secretion. It is concluded that exogenous cyclic 3′,5′-adenosine monophosphate and its dibutyryl derivative may not be considered as analogous and that both compounds may contribute to study growth hormone release in normal subjects and in patients with growth abnormalities.

Increased hypothalamic somatostatin mRNA following dexamethasone administration in rats

1992 ◽  
Vol 127 (5) ◽  
pp. 416-419 ◽  
Author(s):  
Koji Nakagawa ◽  
Tatsuya Ishizuka ◽  
Chikara Shimizu ◽  
Yoshito Ito ◽  
Ichiji Wakabayashi
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Female Rats ◽  
Mrna Levels ◽  
Plasma Growth Hormone ◽  
Hormone Production ◽  
Blot Technique ◽  
Series Of Experiments

There is increasing evidence to suggest that supraphysiological doses of glucocorticoids suppress growth hormone secretion in vivo by augmenting somatostatin release from the hypothalamus; previously, we reported an increase in hypothalamic somatostatin content in dexamethasone-treated rats. To further examine whether the production of somatostatin really is augmented, hypothalamic somatostatin mRNA levels were determined by the Northern blot technique in female rats receiving 330 μg of dexamethasone daily for three days. In two series of experiments, hypothalamic somatostatin mRNA levels in dexamethasone-treated rats were significantly (p<0.05) increased to 133±19 (mean±sd)% and 153±38% of the controls. In the dexamethasone-treated rats, plasma growth hormone levels were markedly suppressed compared with those of the controls. These results further support the hypothesis that pharmacological doses of glucocorticoids increase the production and release of somatostatin from the hypothalamus and thus inhibit growth hormone secretion, overriding the direct stimulatory effect of glucocorticoids on growth hormone production at the pituitary level.

Desensitization from long-term intranasal treatment with hexarelin does not interfere with the biological effects of this growth hormone-releasing peptide in short children

1996 ◽  
Vol 134 (6) ◽  
pp. 716-719 ◽  
Author(s):  
Beatrice Klinger ◽  
Aviva Silbergeld ◽  
Romano Deghenghi ◽  
Jenny Frenkel ◽  
Zvi Laron
Keyword(s):  
Growth Hormone ◽  
Growth Velocity ◽  
Biological Effects ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Human Growth ◽  
Pediatric Endocrinology ◽  
Short Children ◽  
The Mean

Klinger B, Silbergeld A, Deghenghi R, Frenkel J, Laron Z. Desensitization from long-term intranasal treatment with hexarelin does not interfere with the biological effects of this growth hormonereleasing peptide in short children. Eur J Endocrinol 1996;134:716–9. ISSN 0804–4643 A clinical, prospective experiment was carried out to determine whether long-term intranasal administration of the growth hormone-releasing peptide hexarelin (His-d-2-methyl-Trp-Ala-Trp-d-Phe-Lys-NH2) affects pituitary growth hormone secretion. Hexarelin (60 μg/kg t.i.d.) was administered to seven prepubertal constitutionally short children (mean age ±sd = 7.6 ± 2.4 years). Serum human growth hormone (hGH) response to an intranasal (20 μg/kg) and intravenous (1 μg/kg) bolus of hexarelin before, during and after 6–10 months of treatment was measured. The mean (±sd) peak rise of hGH to the intranasal bolus before treatment was 70.6 ± mU/I. After 7 days of hexarelin treatment, mean peak values dropped to 34.1 ±15.7 mU/l (p < 0.002) and thereafter remained constant for 6 months of treatment at 37.5 10.3 ±mU/l (p < 0.03). The pretreatment peak to the iv hexarelin bolus was 84.8 52.5 ±mU/l, and at the end of the treatment period it was 19.8 10.9 ±mU/l (p < 0.05). Three months after stopping treatment the mean (±sd) hGH response rose to 42.1 ±4.7 mU/l (p < 0.005). Growth velocity increased from 5.3±0.9 cm/year (before treatment) to 7.4 1.6 cm/year at ±6–10 months of treatment (p < 0.005). In conclusion, the partial suppression of pituitary hGH responsiveness to long-term intranasal hexarelin treatment, probably due to desensitization, does not affect the observed increase in growth velocity. Z Laron, Pediatric Endocrinology, 11 El Al Street, Ramat Efal, 52960, Israel

Microinjection of Dihydrotestosterone into the Medial Preoptic Area Produces Male-Like Pattern of Growth Hormone Secretion in Ovariectomized Female Rats

2002 ◽  
Vol 75 (6) ◽  
pp. 384-391 ◽  
Author(s):  
Reiko Tokita ◽  
Yoko Kasagi ◽  
Tomoko Nakata ◽  
Kensaku Sakae ◽  
Toshihiro Imaki ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Preoptic Area ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Medial Preoptic Area ◽  
Female Rats

CHANGES IN PLASMA GROWTH HORMONE AND INSULIN OF THE HUMAN FOETUS FOLLOWING HYSTEROTOMY

1971 ◽  
Vol 66 (4) ◽  
pp. 577-586 ◽  
Author(s):  
R. C. Turner ◽  
B. Schneeloch ◽  
P. Paterson
Keyword(s):  
Growth Hormone ◽  
Plasma Insulin ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Immunoreactive Insulin ◽  
Plasma Growth Hormone ◽  
Plasma Insulin Concentration ◽  
Plasma Immunoreactive Insulin ◽  
The Mean ◽  
Serial Samples

ABSTRACT Plasma immunoreactive insulin and growth hormone of 20–24 weeks' gestation human foetuses were assayed in serial samples following delivery by hysterotomy. The mean umbilical cord plasma growth hormone concentration was 71 ng/ml (range 13–120 ng/ml) and the mean plasma insulin was 5 μU/ml (range 2–8 μU/ml). Following delivery the growth hormone levels increased, but there was no significant change in plasma insulin concentration. The hypothalamic-hypophyseal axis controlling growth hormone secretion appears to be developed by 20 weeks' gestation, and »stress« appears to be a provocative stimulus.

Growth hormone secretion in pubertal and adult subjects

1982 ◽  
Vol 99 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Francesco Minuto ◽  
Antonina Barreca ◽  
Silvano Ferrini ◽  
Giancarlo Mazzocchi ◽  
Patrizia Del Monte ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Pubertal Stage ◽  
Pubertal Maturation ◽  
Significant Difference ◽  
Pubertal Stages ◽  
The Mean ◽  
Stage 1 ◽  
Mean Concentration

Abstract. GH responsiveness to insulin-induced hypoglycaemia and its circadian secretion were studied in a group of subjects in different pubertal stages. The GH peak after insulin was minimal in stage 1 boys (7.6 ± 1.3 (sem) ng/ml) and increased progressively, in parallel with pubertal maturation, reaching a maximum in the adult state (20 ± 4.0 ng/ml); the basal value was superimposable in all groups studied. The circadian secretion showed a sleep-related surge which was almost identical in the different stages; however in pubertal stage 1 boys multiple secretory peaks were observed, mainly during waking hours. A statistically significant difference (P < 0.05) was observed in the mean concentration recorded during the day with a maximum in stage 1 boys (2.7 ± 0.2 ng/ml) and a gradual decrease to a minimum in adults (1.2 ± 0.3 ng/ml). This pattern seems to suggest that a pulsatile rhythm is present in boys, similar to that observed for gonadotrophins.

scholarly journals Effect of neonatal thyroidectomy on growth hormone secretion in the rat

1998 ◽  
Vol 157 (2) ◽  
pp. 245-250 ◽  
Author(s):  
S Kitauchi ◽  
H Yamanouchi ◽  
N Hirano ◽  
S Tone ◽  
M Shiino
Keyword(s):  
Growth Hormone ◽  
Thyroid Hormone ◽  
Anterior Pituitary ◽  
Northern Blot Analysis ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Mrna Levels ◽  
Gh Cells ◽  
Neonatal Life ◽  
Significant Difference

The influence of neonatal thyroidectomy (Tx) on GH production was investigated by means of Northern blot analysis. Tx resulted in a significant decrease in pituitary GH mRNA levels after 10, 15 and 20 days. The changes of pituitary GH mRNA were soon reflected in pituitary GH content. There was, however, no significant difference in pituitary GH mRNA levels and GH content between Tx and sham-operated rats at 5 days old. The pituitary GH cells were significantly decreased in number 15 and 20 days after Tx. These data suggest that GH mRNA is transcribed, independent of thyroid hormone, in the rat anterior pituitary gland during early neonatal life. In addition, the present study ascertained that GH dependence on thyroid hormone is acquired between the 5th and 10th day of neonatal life.

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