Anterior pituitary hormones, role

Rettori, V., Milenkovic, L., Riedel, M. McCann, S.M. (1990b) Physiological role of neuropeptide Y (NPY) in control of anterior pituitary hormone release in the rat. Endocrinol. Exp. 24, 37-45. 

Like other anterior pituitary hormones, prolactin is secreted in a pulsatile manner. Prolactin is unique among the anterior pituitary hormones in that hypothalamic regulation of its secretion is predominantly inhibitory. The major regulator of prolactin secretion is dopamine, which is released by tuberoinfundibular neurons and interacts with the Dj receptor on lactotropes to inhibit prolactin secretion. A number of putative prolactin-releasing factors have been described, but their physiological roles are unclear. Under certain pathophysiological conditions, such as severe primary hypothyroidism, persistently elevated levels of TRH can induce hyperprolactinemia and consequent galactorrhea. 

Barden N, Labrie F. J Receptor for thyrotropin-releasing hormone in plasma membranes of bovine anterior pituitary gland. Role of lipids. Biol Chem 1973 248 7601-7606. 

Prolactin is an essential hormone for normal production of breast milk following childbirth. It also plays a pivotal role in a variety of reproductive functions. Prolactin is regulated primarily by the hypothalamus-pituitary axis and secreted solely by the lactotroph cells of the anterior pituitary gland. Under normal conditions, secretion of prolactin is predominantly under inhibitory control by dopamine and acts on the D2 receptors located on the lactotroph cells. Increase of hypothalamic thyrotropin-releasing hormone (TRH) in primary hypothyroidism can stimulate the release of prolactin. 

The acute CNS effects of MDMA administration are mediated by the release of monoamine transmitters, with the subsequent activation of presynaptic and postsynaptic receptor sites.40 As specific examples in rats, MDMA suppresses 5-HT cell firing, evokes neuroendocrine secretion, and stimulates locomotor activity. MDMA-induced suppression of 5-HT cell firing in the dorsal and median raphe involves activation of presynaptic 5-HT1A autoreceptors by endogenous 5-HT.4142 Neuroendocrine effects of MDMA include secretion of prolactin from the anterior pituitary and corticosterone from the adrenal glands 43 Evidence supports the notion that these MDMA-induced hormonal effects are mediated via postsynaptic 5-HT2 receptors in the hypothalamus, which are activated by released 5-HT. MDMA elicits a unique profile of locomotor effects characterized by forward locomotion and elements of the 5-HT behavioral syndrome such as flattened body posture, Straub tail, and forepaw treading.44 6 The complex motor effects of MDMA are dependent on monoamine release followed by activation of multiple postsynaptic 5-HT and DA receptor subtypes in the brain,47 but the precise role of specific receptor subtypes is still under investigation. 

In summary, the menstrual cycle is primarily regulated by the interaction between pituitary and ovarian hormones. Also, releasing hormones from the hypothalamus plays a role in controlling female reproduction through their effects on LH and FSH release from the anterior pituitary.7 A complex series of positive and negative feedback mechanisms control the cyclic release of various female hormones.22,81,97 For instance, increased estrogen secretion in the follicular... 

---