Hypokretiini

Hypokretiini, also known as growth hormone-releasing hormone (GHRH), is a peptide hormone that plays a crucial role in the regulation of growth hormone (GH) secretion. It is produced by the hypothalamus, a region of the brain, and is released into the hypophyseal portal system, which directly connects to the anterior pituitary gland. The anterior pituitary gland, in turn, responds to hypokretiini by releasing growth hormone into the bloodstream.

Hypokretiini is a decapeptide, consisting of 10 amino acids. Its sequence is highly conserved across different species, indicating its evolutionary importance. The hormone is released in a pulsatile manner, with peaks occurring during the night and early morning hours. This pulsatile release is essential for maintaining normal GH levels and is regulated by various factors, including sleep, stress, and nutrition.

Hypokretiini's primary function is to stimulate the release of growth hormone from the anterior pituitary gland. Growth hormone, in turn, plays a vital role in various physiological processes, including growth, metabolism, and tissue repair. Hypokretiini also has other effects on the body, such as regulating appetite and influencing the immune system.

The secretion of hypokretiini is regulated by several factors, including the presence of growth hormone in the bloodstream, the level of glucose, and the presence of certain neurotransmitters. For example, the presence of growth hormone in the bloodstream can inhibit the release of hypokretiini, creating a negative feedback loop that helps maintain normal GH levels.

Hypokretiini deficiency or dysfunction can lead to various health issues, including growth hormone deficiency, which can result in short stature, decreased muscle mass, and other metabolic abnormalities. Conversely, excessive hypokretiini secretion can lead to acromegaly, a condition characterized by excessive growth hormone production and the resulting enlargement of various tissues and organs.