What is the secretion of human growth hormone

Growth hormone is mainly secreted by pituitary cells in the anterior pituitary gland. Its secretion is regulated by both hypothalamic growth hormone releasing hormone and somatostatin, with influencing factors including sleep quality, exercise intensity, nutritional status, age stage, and stress level.

1. Pituitary secretion:

Eosinophils in the anterior pituitary gland synthesize and secrete growth hormone, accounting for 35% -45% of the total number of pituitary cells. These types of cells contain special secretory granules that release growth hormone into the bloodstream through exocytosis. Their secretion exhibits a pulse like pattern, reaching its peak during deep sleep at night.

2. Hypothalamic regulation:

Growth hormone releasing hormone secreted by the hypothalamic arcuate nucleus stimulates the pituitary gland through the pituitary portal system, while somatostatin secreted by the paraventricular nucleus has an inhibitory effect. The alternating action of two neuropeptides forms a secretion pulse that occurs every 3-5 hours, and during puberty, the pulse amplitude can reach 10-20 times the baseline value.

3. Sleep effects:

The secretion of growth hormone during slow wave sleep accounts for 70% of the total daily amount, and insufficient deep sleep can lead to a 30% -50% decrease in secretion. The peak of growth hormone in children at night can reach 15-40ng/ml, while in adults it usually does not exceed 10ng/ml. This circadian rhythm is indirectly regulated by the suprachiasmatic nucleus through melatonin.

4. Nutritional metabolism:

Low blood sugar can stimulate an increase in growth hormone secretion by 2-3 times, and elevated levels of amino acids in the blood, especially arginine, can also promote secretion. On the contrary, an increase in free fatty acids can inhibit secretion, and the basal value of growth hormone in obese individuals is often more than 50% lower than that in normal weight individuals.

5. Age change:

The secretion during adolescence reaches a lifelong peak, and decreases by about 15% every decade after the age of 20. At the age of 60, the total secretion in 24 hours is only 25% of that in adolescence. This attenuation is related to reduced expression of growth hormone releasing hormone receptors, increased tension of somatostatin, and degeneration of pituitary cell function.

Maintaining a regular daily routine, especially during the deep sleep period from 22:00 to 2am, moderate intake of foods rich in arginine such as nuts and seafood, high-intensity interval exercise, and controlling body fat percentage within the normal range, all help maintain physiological growth hormone secretion levels. If people over 40 years old experience symptoms of growth hormone deficiency such as sustained fatigue and significant decrease in muscle mass, it is recommended to evaluate pituitary function through professional tests such as insulin hypoglycemia testing.