Tehran University Medical Journal

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Background: The effects of growth hormone (GH) on bone density in healthy adults is controversial. This study was performed to evaluate the effects of GH administration on bone density under controlled conditions in healthy adult rabbits.

Methods: Twenty healthy adult New Zealand white rabbits of both sexes were included in the study. The rabbits were divided into two groups. The experiment group received human GH and the controls placebo for three months. The density of femur and humerus were measured at proximal epiphysis, mid shaft and distal epiphysis by radiography, aluminum step-wedge and appropriate software. Measurements were performed in five stages, once before and four times after the administration of GH or placebo, with 3-week intervals.

Results: The mean concentration of serum insulin-like growth factor I (IGF-I) increased significantly after GH administration (P<0.05) in the experiment group. Bone density generally increased in all regions except the distal epiphysis of femur in the test group, but significant difference were only seen in the midshaft of femur in comparison to the controls (P<0.05). In the second stage, bone density decreased slightly in all regions except distal epiphysis of femur, but it increased in the next stages.

Conclusion: GH can increase bone density (mostly cortical bone) in adult rabbits. According to the similarities seen between growth hormone effects in rabbit and humans, this study suggests rabbits as a model for studying GH effects on bone density in acromegaly, growth hormone deficiency and even in healthy adult humans.

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Background: Body weight is regulated by both food intake and energy expenditure. Ghrelin, a hormone produced by the stomach and pancreas, enhances appetite. This study was undertaken to determine the effects of intermittent treadmill running on acylated ghrelin and appetite in individuals with obesity. Methods: Nine inactive male students, with a mean age of 20.56±0.48 yrs, a body mass index of 32.68±0.84 kg/m2 and a maximum oxygen uptake of 34.21±1.48 ml/kg/min, participated in the study in two trials (control and exercise) in a counterbalanced, randomized design. The protocol included intermittent running with a constant intensity at 65% of VO2 max on a treadmill. Blood samples were collected before, during, and 2h after cessation of the exercise. Results: Acylated ghrelin concentrations and hunger ratings decreased significantly in the second phase and remained lower than baseline (P=0.006 and P=0.002, respectively) at the end of the exercise. The total area under the curve values and hunger ratings (all P<0.0005) were significantly lower in the exercise trial compared with the control state. Similarly, growth hormone rose significantly at the second phase and remained higher than baseline (P=0.033) at the end of the exercise trial. Conclusion: These findings indicate that acylated ghrelin and appetite are reduced by running at 65% of VO2 max and remain lower than baseline even two hours afterwards in individuals with obesity. Growth hormone seems to be more responsible for this suppression. Further studies are required to investigate whether this protocol could elicit the same effects in short-term training programs.

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Background: The prevalence of obesity has risen enormously over the past few decad-es. Both food intake (Appetite) and energy expenditure can influence body weight. Acylated ghrelin enhances appetite, and its plasma level is suppressed by growth horm-one. The present study, examines the effects of an intermittent exercise with progress-ive intensities on acylated ghrelin, appetite, and growth hormone in inactive male students with two levels of obesity.
Methods: Eleven inactive males were allocated into two groups on the basis of their body mass index (BMI). Six subjects in group one, BMI= 31.18±0.92 kg/m2, and five subjects in group two, BMI= 36.94±2.25 kg/m2, ran on the treadmill with progressive intensities of 50, 60, 70 and 80% of VO2max for 10, 10, 5, and 2 min respectively. Blood samples were collected before the exercise (as the resting values), after each workload (during the exercise), and at 30, 60, and 120 min (during recovery).
Results: Plasma acylated ghrelin concentrations and hunger ratings in two groups were decreased and remained significantly lower than resting values (P=0.008 and P=0.002 respectively) at the end of the trial and there was no significant differences between groups. Growth hormone levels in two groups were increased and remained significant-ly higher than resting values (groups one P=0.012, group two P=0.005) at the end of the trial and there was no significant differences between groups. In addition, there were no significant differences between area under the curves (AUC) values over total periods for acylated ghrelin, hunger ratings, and growth hormone in two groups.
Conclusion: These findings indicate that individuals with two levels of obesity have the same response to the different intensities of treadmill running and two hours thereafter during recovery period, which can be considered for designing a more effective weighting loss training program.

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Results: Height increase index (HSDS) was obtained with the use of growth hormone combined with one of the aromatase inhibitors (0.38-3.58=95%CI) (SMD=0.98), with the use of growth hormone (0.62-1.14=95%CI) (SMD=0.88), with the use of Letrozole (0.51-16.51=95%CI) (SMD=0.83), with the use of Oxandrolone (0.99-0.99=95%CI) (SMD=0.56), and with the use of Anastrozole (0.00-0.63=95%CI) (SMD=0.31), which shows that all these drugs have a significant effect on height increase. (P<0.05) Conclusion: Although the effect of growth hormone on height increase was greater than that of aromatase inhibitors, but according to our results, adding an aromatase inhibitor to growth hormone can increase the effectiveness of it.

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