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,.

Endocrine treatment of male-to-female transsexuals using gonadotropin-releasing hormone agonist.

Abstract: In transsexual people, cross-sex hormone therapy is an important component of medical treatment. In male-to-female transsexuals, feminizing effects should be achieved before irreversible sex reassignment surgery (SRS) is considered. The most common treatment regimen in male-to-female transsexuals is a combination of ethinyl oestradiol and cyproterone acetate, with the exception of transdermal oestradiol-17beta in individuals over the age of 40. The mortality and morbidity rates with this treatment regimen have been reported in more than 800 patients. Typical side effects include venous thrombosis, elevated liver enzymes, symptomatic gallstones, hyperprolactinaemia and depression. Sixty male-to-female transsexuals were treated with monthly injections of gonadotropin-releasing hormone agonist (GnRHa) and oral oestradiol-17beta valerate for 2 years to achieve feminisation until SRS. There was a significant decline in gonadotropins, total testosterone and calculated free testosterone. In general, the treatment regimen was well accepted. An equal increase in breast size was achieved compared to common hormone therapy. Two side effects were documented. One, venous thrombosis, occurred in a patient with a homozygous MTHFR mutation. One patient was found to be suffering from symptomatic preexisting gallstones. No other complications were documented. Liver enzymes, lipids, and prolactin levels were unchanged. Significantly increased oestradiol and SHBG serum levels were detectable. In addition, an increase in bone mass density, in the femoral neck and lumbar spine, was recorded. We conclude that cross-sex hormone treatment of male-to-female transsexuals using GnRHa and oestradiol-17beta valerate is effective, and side effects and complication rates can be reduced using the treatment regimen presented here.

Catecholamines of supposed inhibitory hypophysiotrophic function suppress action potentials in prolactin cells

Abstract: THE anterior lobe of the pituitary gland has a uniquely important function in the endocrine system, for its six different endocrine cell types constitute the major endocrine link between the brain and the rest of the body. The brain is known to control this remarkable composite gland through specialised neurones lodged in the hypothalamus that elaborate and release hypophysiotrophic factors; these are carried by the hypophysial portal blood vessels to act on their respective target cells through stimulation or inhibition of secretory activity1,2. However, the way in which these factors act at the cellular level is uncertain, although discharge of the various hormones of the anterior pituitary lobe is known to show calcium dependence and can be induced by depolarising concentrations of potassium3–5; this pattern of endocrine behaviour was first recognised in adrenal chromaffin cells6 and is consistent with the calcium hypothesis of stimulus–secretion coupling7, which, in chromaffin and some other cells, is associated with electrical excitability8–13. It is therefore of much interest that normal gland cells of the anterior pituitary lobe14,15, like their neoplastic counterparts16–18, have been found to generate action potentials with a calcium component indicative of influx of calcium ions; furthermore, the frequency of action potentials can be increased in some of these cells by thyrotropin releasing factor (TRF)14. This has prompted the suggestion that it may be through the initiation or modulation of action potentials that the brain, through the hypophysiotrophic factors, regulates secretion in the anterior pituitary14. However, the evidence which supports this scheme is scanty. The experiments with TRF were carried out on disaggregated anterior pituitary lobes of rats which contain six different endocrine cells, and the method did not allow identification of the cells stimulated by TRF; thus, it could only be supposed that they were the appropriate target cells14. Clearly, it is essential that evidence be obtained on the electrical behaviour of normal anterior lobe cells of defined type, and the effects thereon of specific and relevant hypophysiotrophic factors. Here we report that normal prolactin cells generate spontaneous action potentials which are suppressed by hypothalmic catecholamines known to inhibit prolactin secretion.

In vivo antisense antagonism of vasoactive intestinal peptide in the suprachiasmatic nuclei causes aging-like changes in the estradiol-induced luteinizing hormone and prolactin surges

Abstract: In mammals, the suprachiasmatic nuclei (SCN) regulate the timing of LH surges. Recent evidence suggests that vasoactive intestinal peptide (VIP), an abundantly expressed neuropeptide of the SCN, communicates time of day information from the SCN to GnRH neurons. VIP levels in the SCN decrease with age and may be responsible for alterations in LH surges that become apparent in middle-aged rats. We wished to determine whether suppression of VIP synthesis, through antisense oligonucleotides (oligos) directed at the SCN, results in 1) selective suppression of VIP levels in the SCN and 2) aging-like changes in the secretion of LH and PRL. To test the specificity of antisense oligo treatment, rats were ovariectomized and treated with estradiol. Antisense or control random oligos were infused into the peri-SCN region through stereotaxically placed bilateral cannulas. Beginning at lights off, rats were maintained in constant dim red illumination throughout the remainder of the experiment. They were killed at speci...