QS Study

Regulation of the Growth Hormone Secretion

Growth hormone secreted by somatotropes of an anterior pituitary gland. It helps to control body composition, body fluids, muscle and bone growth, sugar and fat metabolism, and perhaps heart function. The main control is exerted by two neuroendocrine hormones, GH-releasing hormone, and somatostatin, though other hypothalamic neuropeptides, directly and indirectly, take part in this procedure. An increased secretion of growth hormone has been shown during insulin and tolbutamide induced hypoglycemia, during work out and during severe or chronic starvation.

(A) Regulation by hypothalamus: Hypothalamus secretes growth hormone releasing hormones (GHRH) and growth hormone inhibiting hansom (GHIR).

GH secretion is under feed bark control. It increases circulatory somatomedin C (Also known as insulin-like growth factor-1) in turn exerts a direct inhibitory to the pituitary gland. It also stimulates somatostatin (ss) secretion.

(B) Regulation of GH by different stimuli:

Stimuli that increase GH Secretion:

(i) Deficiency of energy substrate –

  • Hypoglycemia,
  • 2-Deoxyglucose,
  • Exercise,
  • Fasting.

(ii) Increase in circulating levels of certain amino acids –

  • Protein meal,
  • Infusion of arginine and some other amino acids.

(iii) Glucagon

(iv) Stressful stimuli –

  • Pyrogen,
  • Lysine vasopressin,
  • Psychological stress.

(v) Going to sleep,

(vi) L-Dopa and alpha adrenergic agonists,

(vii) Estrogens and androgens.

Stimuli that increase GH Secretion – REM sleep, Glucose, Cortisol, FFA, Growth hormone, Aging, Obesity etc.