Effects of Intracerebroventricularly and Intraperitoneally Administered Growth Hormone on Body Weight and Food Intake in fa/fa Zucker Rats

Abstract

Growth hormone (GH) possesses multiple metabolic effects, in particular with regard to glucose and lipid homeostasis. Studies on the effects of GH on body weight and food and water intake are scarce and have yielded controversial results. We investigated the effects of different modes of GH administration on the parameters of body weight and food intake as well as on insulin and leptin concentrations in fa/fa Zucker rats. In control experiments, aqua pro injectione was given. GH was administered over a time period of 11 days at a daily dose of 250 µg intraperitoneally (i.p.) and 25 µg intracerebroventricularly (i.c.v.). While both food intake and body weight were found to be unaltered in the four groups after this observation period, there was an enhanced food intake and consecutively an increase in body weight over the day period when compared to the night period in the groups of rats that received GH i.c.v. or i.p. This tendency was also shown for water intake. Insulin and leptin concentrations were similar in all groups. Thus, injection of GH appears to modify food intake-related behavior, since the periods of enhanced food and water intake were shifted from night- to daytime. Thus, while in general the metabolic parameters remained unchanged, the activity pattern was clearly modified.

Bovine Growth Hormone Transgenic Mice Are Resistant to Diet-Induced Obesity but Develop Hyperphagia, Dyslipidemia, and Diabetes on a High-Fat Diet

“…We observed that the RER increased in the early afternoon in the bGH mice but several hours later in the littermate controls. This finding indicates that the transgenic mice eat more during the light phase, which is in line with the finding of another study (16) showing that GH treatment of Zucker rats made them eat more during the day period without changing the total food intake. Thus, it can be concluded that the effect of GH on food intake is dependent on the content of dietary fat and that GH probably influences the diurnal rhythm of food intake.…”

“…GH has been shown to increase food intake in children (12) and in experimental animals (13) but not in all studies (14 -16) including bGH transgenic mice given ordinary low-fat chow (5). It has also been shown that eating behavior changes after GH administration (16). However, no studies have been per-formed to investigate the effect of GH on intake of low-vs. high-fat diet (HFD).…”

Growth Hormone Overexpression in the Central Nervous System Results in Hyperphagia-Induced Obesity Associated With Insulin Resistance and Dyslipidemia

“…GH has also been shown to increase food intake in experimental animals in some (5) but not all studies (13)(14)(15)(16). In addition, GH administration has been shown to change eating behavior (16).…”

Leptin and leptin receptor expression in skeletal muscle and adipose tissue in response to in vivo porcine somatotropin treatment1,2

“…Previous studies in humans and rodents have demonstrated that somatotropin concentrations can be correlated with increased (Iglesias et al, 2002 ), decreased (Eden-Engstrom et al, 2003;Malmlof and Johansen, 2003), or normal (Boni-Schnetzler et al, 1999;Bolanowski et al, 2002;Schulz et al, 2002) serum leptin concentrations. The serum leptin response to pST may depend on the status of carcass adipose mass, serum insulin, serum glucocorticoid, renal state, pre-experimental ST concentration, timing of collection, or other factors.…”