Prolactin

About: Prolactin is a research topic. Over the lifetime, 22356 publications have been published within this topic receiving 609537 citations. The topic is also known as: lactotropin, & PRL,.

Focus on prolactin as a metabolic hormone

Abstract: New information about the effects of prolactin (PRL) on metabolic processes warrants re-evaluation of the overall metabolic actions of PRL. PRL affects metabolic homeostasis by regulating key enzymes and transporters that are associated with glucose and lipid metabolism in several target organs. In the lactating mammary gland, PRL increases the production of milk proteins, lactose and lipids. In adipose tissue, PRL generally suppresses lipid storage and adipokine release. PRL supports the growth of pancreatic islets, stimulates insulin secretion and increases citrate production in the prostate. A specific case is made for PRL in the human breast and adipose tissue, where it acts as a circulating hormone and an autocrine or paracrine factor. Although the overall effects of PRL on body composition are modest and species specific, PRL might be involved in the manifestation of insulin resistance.

The effect of neuroleptics on serum prolactin in schizophrenic patients.

Abstract: • Serum prolactin levels were studied before and during longterm administration of phenothiazines on a twice daily schedule to 27 newly admitted schizophrenic patients. An increase in serum prolactin is believed to be a reflection of inhibition of dopamine receptors in the hypothalamopituitary axis. By 72 hours after the initiation of treatment, all 27 patients had persistently elevated serum prolactin levels averaging 3.2-fold and 3.8-fold in men and women, respectively. There was a lag between clinical response and dopamine blockade, as indicated by serum prolactin levels in most patients. Serum prolactin levels remained elevated during the one- to three-month period subjects were studied, suggesting there was no tolerance to this effect of phenothiazines. Serum prolactin levels tended to be higher with thioridazine than on equivalent doses of chlorpromazine or trifluoperazine hydrochloride. There was some evidence that the magnitude of the serum prolactin elevation correlated with clinical response. After cessation of phenothiazines, serum prolactin levels rapidly reverted to normal within 48 to 96 hours.

Clonal strains of hormone-producing pituitary cells.

Abstract: Publisher Summary This chapter discusses clonal strains of pituitary tumor cells that synthesize and secrete prolactin, growth hormone and adrenocorticotropic hormone (ACTH). The rates of biosynthesis of the specific hormonal peptides by these clonal strains are high and they respond in culture to many of the same regulatory factors as normal pituitary cells do in situ. Strains of homogeneous populations of functional cells serve as useful model systems for determining the mechanisms of action of factors that regulate the release and synthesis of prolactin, growth hormone, and ACTH. Several epithelial cell strains have been cloned, and some have been maintained in continuous culture for as long as 10 years without loss of hormone production. Growth hormone (GH) cells produce large amounts of growth hormone and prolactin. The biosynthesis and release of these two protein hormones are modulated by specific factors that have been found to influence the pituitary gland in the intact animal.

Serotonergic function in depression. Prolactin response to intravenous tryptophan in depressed patients and healthy subjects.

Abstract: • There is considerable evidence that serotonergic function may be reduced in the brains of depressed patients. Serotonin is an effective stimulant of prolactin release, and intravenous (IV) tryptophan (the amino acid precursor of serotonin), when administered to healthy subjects, produces a reliable and robust increase in serum prolactin level. To evaluate serotonergic function in depressed patients, we gave 25 patients and 19 age- and sex-matched controls tryptophan, 7 g IV. There was a marked blunting of the maximal prolactin response to the tryptophan in both the male and female patients. The patient control differences could not be accounted for on the basis of age, sex, or time without medications. The data provide strong support for a possible serotonergic abnormality in depression.

Membrane effects of thyrotropin-releasing hormone and estrogen shown by intracellular recording from pituitary cells

Abstract: The effects of thyrotropin-releasing hormone and 17 beta-estradiol on the electrical membrane properties of a prolactin-secretin pituitary cell line (GH3/B6) were studied with intracellular microelectrode recordings. Of the cells tested, 50 percent were excitable and displayed calcium-dependent action potentials when depolarized. When injected directly on the membrane of an excitable cell, thyrotropin-releasing hormone and 17 beta-estradiol induced action potentials within 1 minute. The spiking activity was preceded by a progressive increase of the input resistance without any detectable change in the resting membrane polarization. The results reveal a rapid effect of both substances on the membrane of GH3/B6 cells. In the case of thyrotropin-releasing hormone, which has both a short-term effect on release of prolactin and a long-term effect on its synthesis, the induced electrical activity may be associated with the stimulation of prolactin production. The physiological implication of 17 beta-estradiol-induced, calcium-dependent spiking activity remains to be elucidated.