scholarly journals The episodic secretory pattern of growth hormone regulates liver carbonic anhydrase III. Studies in normal and mutant growth-hormone-deficient dwarf rats

1990 ◽  
Vol 266 (1) ◽  
pp. 69-74 ◽  
Author(s):  
S Jeffery ◽  
N D Carter ◽  
R G Clark ◽  
I C A F Robinson
Keyword(s):  
Growth Hormone ◽  
Carbonic Anhydrase ◽  
Body Weight Gain ◽  
Female Rats ◽  
Male Rat ◽  
Normal Female ◽  
Sexually Dimorphic ◽  
Carbonic Anhydrase Iii ◽  
Plasma Gh ◽  
Secretory Pattern

Carbonic anhydrase III (CAIII) occurs in male rat liver at concentrations twenty times those in the female, and is sensitive to the pattern of growth hormone (GH) release. Males release GH episodically and have high concentrations of CAIII; females produce GH in a more continuous fashion and have lower CAIII levels. In normal female rats, the endogenous GH secretory pattern was masculinized, either by regular injections of GH-releasing factor (GRF) or by intermittent infusions of somatostatin (90 min on/90 min off). Both treatments induced regular GH pulses and stimulated growth, but only intermittent somatostatin infusions raised CAIII levels (controls, 1.5 +/- 0.5; somatostatin-treated, 9.0 +/- 2.9 micrograms/mg; means +/- S.D.). GRF pulses (4 micrograms every 4 h) did not however raise CAIII levels (controls 1.8 +/- 0.5; GRF-treated 1.4 +/- 0.4 micrograms/mg). Surprisingly, hepatic CAIII is also sexually dimorphic (males, 18.8 +/- 3; females, 2.22 +/- 0.4 micrograms/mg) in a GH-deficient dwarf rat strain which has low plasma GH levels without 3-hourly GH peaks. Intermittent somatostatin infusions in female dwarf rats partially masculinized hepatic CAIII, an effect reduced by co-infusion with GRF. This CAIII response was not secondary to growth induction, since neither somatostatin nor GRF stimulated growth in dwarf rats, and pulses of exogenous GH stimulated growth in female dwarfs without masculinizing CAIII levels. Furthermore, continuous GH infusion in male dwarf rats partially feminized hepatic CAIII levels (to 9.1 +/- 2.4 micrograms/mg), whereas infusions of insulin-like growth factor-1, which induced the same body weight gain, did not affect hepatic CAIII (20.8 +/- 6 micrograms/mg). These results show that hepatic CAIII expression is highly sensitive to the endogenous GH secretory pattern, independent of growth. They also implicate the low basal GH levels between pulses, rather than the peak GH levels, as the primary determinant of the sexually dimorphic hepatic CAIII expression in the rat.

Renaturalizing the sexually dimorphic profiles of circulating growth hormone in hypophysectomized rats

1991 ◽  
Vol 124 (3) ◽  
pp. 283-289 ◽  
Author(s):  
Nisar A. Pampori ◽  
Arun K. Agrawal ◽  
Bernard H. Shapiro
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Body Weight Gain ◽  
The Body ◽  
Female Rats ◽  
Male Rats ◽  
Sexually Dimorphic ◽  
Plasma Growth Hormone ◽  
Indwelling Catheter ◽  
Hypophysectomized Rats

Abstract. Hypophysectomy resulted in a total elimination of measurable circulating growth hormone with an associated loss of body weight gain. The typical sexually dimorphic plasma growth hormone patterns: pulsatile profiles in male rats and tonic-like secretion in female rats, were lost. The male- and female-dependent profiles of plasma growth hormone, monitored from serial blood collections, were restored by administering the hormone through a single electrically controlled external pump attached to an indwelling catheter, and by implanting osmotic pumps intraperitoneally, respectively. Restoring the natural patterns of plasma growth hormone in animals devoid of pituitaries, re-initiated body growth. However, the body weight gains in both sexes of hypophysectomized rats were much greater when rat growth hormone was introduced to the animals in a masculine (pulsatile) pattern that appeared to be independent of pulse frequency, rather than in a continuous feminine profile. Subcutaneous injections, the most commonly reported method of administration, produced low-amplitude, long-lasting plasma peaks that were not as effective as pulse infusion in restoring growth. The procedure allows manipulation of the hormone profile (i.e. number of pulses/day, pulse amplitude, and through duration in the pulsatile pattern, and plasma concentration in the tonic pattern) in order to identify, and thus study the presumed salient components of the pattern regulating growth hormone responses.

Stimulation of food intake and weight gain in mature female rats by bovine prolactin and bovine growth hormone

1993 ◽  
Vol 264 (6) ◽  
pp. E986-E992 ◽  
Author(s):  
J. C. Byatt ◽  
N. R. Staten ◽  
W. J. Salsgiver ◽  
J. G. Kostelc ◽  
R. J. Collier
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Weight Gain ◽  
Food Intake ◽  
Body Weight Gain ◽  
Mature Female ◽  
Female Rats ◽  
Bovine Growth Hormone ◽  
Female Rat ◽  
Moisture Percentage

Recombinant bovine prolactin (rbPRL) or bovine growth hormone (rbGH) was administered to mature female rats (10/treatment group) by daily subcutaneous injection for 10 days. Doses ranged from 7 to 5,000 micrograms/day (0.03-24 mg/kg body wt). Both rbPRL and rbGH increased body weight gain and food intake, but these parameters were increased at lower doses of rbPRL (7-63 micrograms/day) than rbGH (> 190 micrograms/day). Weight gain and food intake were maximally stimulated by 190 micrograms/day rbPRL, whereas maximal increased weight gain was obtained with the highest dose of rbGH (5,000 micrograms/day). Total carcass protein was increased by both hormones; however, protein as a percentage of body weight was unchanged. Similarly, neither rbPRL nor rbGH changed the percentage of carcass moisture. Percentage of body fat was increased by rbPRL but was decreased by rbGH. Weight of the gastrointestinal tract and kidneys was increased by both hormones, but increases were in proportion to body weight gain. These data confirm that ungulate prolactin is a hyperphagic agent in the female rat. In addition, they suggest that, while prolactin stimulates growth in mature female rats, this growth is probably not via a somatogenic mechanism.

Significance of the Secretory Pattern of Growth Hormone

Physiology ◽  
1986 ◽  
Vol 1 (2) ◽  
pp. 44-47
Author(s):  
OGP Isakkson ◽  
J-O Jansson ◽  
RG Clark ◽  
I Robinson
Keyword(s):  
Growth Hormone ◽  
Plasma Concentration ◽  
High Amplitude ◽  
Female Rats ◽  
Healthy Children ◽  
Male And Female ◽  
Male And Female Rats ◽  
Low Concentrations ◽  
Lower Amplitude ◽  
Secretory Pattern

The plasma concentration of growth hormone fluctuates widely with pronounced peaks at intervals of a few hours and troughs of nearly vanishingly low concentrations in between. The pattern of secretion varies, and different patterns affect growth differently. Tall children usually have frequent growth hormone peaks of a high amplitude, whereas short, healthy children usually have fewer peaks of a lower amplitude. Male and female rats have different patterns, and a "masculine" pattern promotes growth more than a "feminine" pattern. If the same amount of growth hormone is administered in several pulses rather than continuously, the effect on growth is much greater.

Induction of growth hormone (GH) mRNA by pulsatile GH-releasing hormone in rats is pattern specific

2000 ◽  
Vol 278 (5) ◽  
pp. E885-E891 ◽  
Author(s):  
Russell J. Borski ◽  
Wellington Tsai ◽  
Roberta Demott-Friberg ◽  
Ariel L. Barkan
Keyword(s):  
Growth Hormone ◽  
Weight Gain ◽  
Body Weight Gain ◽  
Somatic Growth ◽  
Pulse Amplitude ◽  
Female Rats ◽  
Mrna Levels ◽  
Female Rat ◽  
Constant Frequency ◽  
Releasing Hormone

Growth hormone-releasing hormone (GHRH) is a main inducer of growth hormone (GH) pulses in most species studied to date. There is no information regarding the pattern of GHRH secretion as a regulator of GH gene expression. We investigated the roles of the parameters of exogenous GHRH administration (frequency, amplitude, and total amount) upon induction of pituitary GH mRNA, GH content, and somatic growth in the female rat. Continuous GHRH infusions were ineffective in altering GH mRNA levels, GH stores, or weight gain. Changing GHRH pulse amplitude between 4, 8, and 16 μg/kg at a constant frequency (Q3.0 h) was only moderately effective in augmenting GH mRNA levels, whereas the 8 μg/kg and 16 μg/kg dosages stimulated weight gain by as much as 60%. When given at a 1.5-h frequency, GHRH doubled the amount of GH mRNA, elevated pituitary GH stores, and stimulated body weight gain. In the rat model, pulsatile but not continuous GHRH administration is effective in inducing pituitary GH mRNA and GH content as well as somatic growth. These studies suggest that the greater growth rate, pituitary mRNA levels, and GH stores seen in male compared with female rats are likely mediated, in part, by the endogenous episodic GHRH secretory pattern present in males.

Testicular regulation of sexual dimorphisms in the ultradian profiles of circulating growth hormone in the chicken

1994 ◽  
Vol 131 (3) ◽  
pp. 313-318 ◽  
Author(s):  
Nisar A Pampori ◽  
Bernard H Shapiro
Keyword(s):  
Growth Hormone ◽  
Right Atrial ◽  
University Of Pennsylvania ◽  
Sexually Dimorphic ◽  
White Leghorn ◽  
Plasma Growth Hormone ◽  
Blood Samples ◽  
Sexual Dimorphisms ◽  
The Common ◽  
Plasma Gh

Pampori NA, Shapiro BH. Testicular regulation of sexual dimorphisms in the ultradian profiles of circulating growth hormone in the chicken. Eur J Endocrinol 1994;131:313–318. ISSN 0804–4643 Ultradian patterns in plasma growth hormone (GH) concentrations were determined in adult white Leghorn roosters, hens and capons. Serial blood samples were collected every 15 min over 8 h through surgically placed chronic indwelling right atrial catheters and assayed for GH content by a homologous radioimmunoassay. In both sexes, GH levels fluctuated episodically, with peak and interpeak periods each lasting about 45 min in both roosters and hens. However, GH concentrations in the peaks and nadirs were 2.5–3.5 times greater in the plasma GH profiles of roosters as compared to hens, which resulted in roosters having higher mean GH concentrations. Caponizing completely feminized the episodic GH secretory profile. In contrast to chickens, the common sexually dimorphic feature in secretory GH profiles of mammals is the enhanced peak frequencing found in females. Bernard H Shapiro, Laboratories of Biochemistry, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104-6048, USA

EXPERIMENTAL EVALUATION OF DIURETICS IN THE RAT

1956 ◽  
Vol 34 (1) ◽  
pp. 903-911
Author(s):  
J. D. McColl ◽  
J. M. Parker ◽  
J. K.W. Ferguson
Keyword(s):  
Carbonic Anhydrase ◽  
Dose Range ◽  
Carbonic Anhydrase Inhibitor ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
High Dose ◽  
Female Rat ◽  
Inhibitor Type ◽  
Almost All

The diuretic response of the male and the female rat to aminophylline has been studied when these animals were pretreated with various concentrations of sodium chloride solution. A linear log dose – response curve was obtained over the dose range employed with male rats pretreated with 0.45% and 2% saline. Male rats exhibited a diuresis with 4% saline which was not increased by aminophylline. Female rats showed diuresis but the responses were more variable for almost all combinations of electrolyte load and xanthine dose. When they were pretreated with 0.45% and 2% saline, aminophylline caused some additional production of urine but this was much less regular than that observed with males. The variation in response to aminophylline after 4% saline was very marked but the trend suggested that the xanthine had a diuretic effect at the high dose. The diuretic responses to a xanthine, a mercurial, and a carbonic anhydrase inhibitor type of diuretic were compared in the male rat. Peak responses were smallest after the mercurial diuretic and greatest with the carbonic anhydrase inhibitor.

scholarly journals Characterization of the binding of human growth hormone to microsomal membranes from rat liver

1976 ◽  
Vol 158 (1) ◽  
pp. 61-69 ◽  
Author(s):  
A C Herington ◽  
N Veith ◽  
H G Burger
Keyword(s):  
Growth Hormone ◽  
Binding Site ◽  
Rat Liver ◽  
Human Growth Hormone ◽  
Human Growth ◽  
Female Rats ◽  
Scatchard Analysis ◽  
Normal Female ◽  
Female Rat ◽  
Hormone Binding

The binding of 125I-labelled human growth hormone to the 100000g microsomal membrane fraction prepared from the livers of normal female rats was dependent on time, temperature, pH, membrane concentration and concentration of 125I-labelled human growth hormone. At 22 degrees C binding reached a steady state after 16h, with the mean maximal specific binding being 20% of the tracer initially added. Dissociation of 125I-labelled human growth hormone from the membranes, after addition of excess of unlabelled hormone, was relatively slow with a half-time greater than 24h. Only minor degradation of the 125I-labelled human growth hormone was observed during incubation with membranes for 16 or 25h at 22 degrees C. Similarly, no significant change in the ability of membranes to bind human growth hormone was evident after preincubation of the membranes for 16 or 25h. Specificity studies showed that up to 90% of the 125I-labelled human growth hormone bound could be displaced by 1 mug of unlabelled hormone. Ovine prolactin also showed considerable competition for the binding site. Non-primate growth-hormone preparations (ovine, bovine, porcine and rat) and non-related hormones (insulin, thyrotropin, lutropin and follitropin) all showed negligible competition. Scatchard analysis of the binding data was consistent with two classes of binding site with binding affinities of 0.64 × 10(10) +/- 0.2 × 10(10)M-1 and 0.03 × 10(10) +/- 0.007 × 10(10)M-1 and corresponding binding capacities of 98.4 +/- 10 fmol/mg of protein and 314.6 +/- 46.3 fmol/mg of protein. These studies provide data which, in general, are consistent with the criteria required for hormone-receptor interaction. However, proof of the thesis that the human-growth-hormone-binding sites in female rat liver represent physiological receptors must await the demonstration of a correlation between hormone binding and a biological response.

scholarly journals Effects of pulsatile secretion of growth hormone (GH) on fat deposition in human GH transgenic rats

2002 ◽  
Vol 15 (2) ◽  
pp. 231-244 ◽  
Author(s):  
Yasufumi Furuhata ◽  
Masugi Nishihara ◽  
Michio Takahashi
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Weight Gain ◽  
Food Intake ◽  
Body Weight Gain ◽  
Weight Ratio ◽  
Tail Length ◽  
Transgenic Rats ◽  
Gh Treatment ◽  
Secretory Pattern

AbstractGrowth hormone (GH) is an endocrine regulator of glucose and lipid metabolism as well as body growth. GH levels are decreased and a unique pulsatile secretory pattern becomes obvious after puberty particularly in males. Coincidentally with this, males tend to deposit body fat. Experimental and clinical evidence has accumulated that obesity is associated with a decrease in GH levels. A strain of transgenic rats has been generated with severe obesity but normal nose-to-tail length, which has low circulating GH levels without pulsatility (human growth hormone (hGH) transgenic rats). The present review mainly focuses on recent and current work analysing the relationship between the occurrence of obesity and low GH levels and/or the absence of GH pulsatility in this transgenic animal model. This model has elevated blood glucose, non-esterified fatty acid, insulin and leptin levels associated with hyperphagia, suggesting that these rats also carry insulin- and leptin-resistant characteristics. hGH transgenic rats were subjected to a pair-feeding treatment to normalize food intake and chronic GH replacement to normalize GH levels. While the pair-feeding for 8 weeks successfully suppressed body-weight gain, the fat pad : body weight ratio remained very similar to freely-eating control hGH transgenic rats, which indicates the hyperphagia is not the sole contributor to the excess fat accumulation in this model. However, continuous elevation of peripheral hGH levels (approximately 2-fold) for 8 weeks by means of a slow-release vehicle resulted in a significant decrease in the fat mass : body weight ratios by 30 %. This GH treatment altered neither food intake nor body-weight gain. Thus, two characteristic phenotypes observed in the hGH transgenic rats, hyperphagia and obesity, seem to be closely related to GH levels and GH secretory pattern. This relationship might be working in the regulation of changes in seasonal body composition in wild animals.

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