Aldosterone will be studied later in the chapter on salt and water balance. Prolactin is released under the balance between prolactin releasing hormone and prolactin inhibiting hormone produced in the hypothalamus. Prolactin acts on the breasts in female mammals to stimulate milk production . Prolactin assists with endocrine function of the testes in male mammals. Growth hormone is released under the balance between growth hormone releasing hormone and growth hormone inhibiting hormone produced in the hypothalamus.
Growth hormone acts on a wide variety of tissues to promote protein synthesis and growth .
Endorphins and enkephalins are natural opiates produced by the anterior pituitary and other parts of the brain and may be involved in decreasing painful sensations . Cortisol is a steroid that is released during stress , reduces the metabolism of glucose, and reduces inflammatory and immune responses. The purpose of glucocorticoids is to maintain carbohydrate reserves . These will be studied in the chapter on animal reproduction. Thyroid hormone stimulates the metabolic activity for growth and development.