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,.

Hyperprolactinaemia and impotence

Abstract: Clinical, laboratory and radiological findings were evaluated in twenty-nine men who had raised serum prolactin concentrations and pituitary tumours. Twenty-one had functionless pituitary tumours ('prolactinomas') and eight had acromegaly. Supraseller extension was detected in twenty of the twenty-six men who had lumbar airencephalography. Three patients were studied before, sixteen before and after and ten only after pituitary ablative therapy. Seventeen of these men complained of complete lack of libido and impotence and six had impaired libido and sexual potency; only six patients in this series denied reproductive symptoms. Thirteen of the impotent subjects had small soft testes, ten reduced facial and body hair and three had marked gynaecomastia. No features of hypogonadism were noted in the six patients without reproductive symptoms and none of the patients had galactorrhoea. Serum prolactin concentrations were higher and serum testosterone concentrations lower in the impotent men compared with those with normal sexual potency. Serum LH and FSH (both basal and in response to LHRH) oestradiol and oestrone concentrations were not different between the two groups and, except in those with post-operative hypopituitarism, were within the normal range. Following successful lowering of prolactin concentrations by surgery or bromocripitine or both, serum testosterone rose and potency returned; by contrast failure to lower prolactin concentrations was associated with persistent impotence and hypogonadism. The endocrine profile of low serum testosterone concentrations with gonadotrophins which had not risen into the range usually seen in primary hypogonadism (together with the parallel increase of LH and testosterone in one patient studied sequentially during treatment which suppressed prolactin levels to normal), suggested that the impaired gonadal function was caused by a prolactin-mediated disturbance of hypothalamic-pituitary function.

Results of stereotactic radiosurgery in patients with hormone-producing pituitary adenomas: factors associated with endocrine normalization.

Abstract: Object. The goal of this study was to determine factors associated with endocrine normalization after radiosurgery is performed in patients with hormone-producing pituitary adenomas. Methods. Between 1990 and 1999, 43 patients with hormone-producing pituitary adenomas underwent radiosurgery: 26 patients with growth hormone (GH)—producing tumors, nine with adrenocorticotrophic hormone—producing tumors, seven with tumors that produced prolactin (PRL) alone, and one with a tumor that secreted both GH and PRL. The median patient age was 42 years. Thirty-seven patients (86%) had undergone surgery earlier and in 30 (70%) there was tumor extension into the cavernous sinus. The product-limit method was used to calculate endocrine normalization while patients were not receiving any hormone-suppressive medication. The median follow-up period after radio-surgery was 36 months (range 12–108 months). In 20 patients (47%) there was normalization of hormone secretion at a median of 14 months (range 2–44 months) after ra...

Effect of apomorphine on growth hormone, prolactin, luteinizing hormone and follicle-stimulating hormone levels in human serum.

Abstract: Apomorphine hydrochloride was administered sc to 12 adult men on 23 occasions. In doses of 0.75–1.0 mg, apomorphine-HCl increased the concentration of growth hormone (GH) in serum above 10 ng/ml in all 12 subjects; peak values occurred at 30–60 min following injection. The increase was antagonized in the 4 subjects pretreated with chlorpromazine. Apomorphine decreased serum prolactin (PRL) levels in 4 subjects but only in a dose of 1.0 or 1.5 mg; the compound failed to decrease chlorpromazineinduced elevated levels of PRL. The drug had no effect on serum LH or FSH. These results are compatible with modulation of GH secretion by a dopaminergic mechanism. Further studies are needed to determine the reliability and potential clinical usefulness of apomorphine as an agent to stimulate GH secretion.

Stimulation of Adenosine 3′:5′-Cyclic Monophosphate Accumulation in Anterior Pituitary Gland In Vitro by Synthetic Luteinizing Hormone-Releasing Hormone

Abstract: A near-maximal dose (20 ng/ml) of synthetic luteinizing hormone(LH)-releasing hormone/follicle-stimulating hormone(FSH)-releasing hormone added to incubated anterior pituitary tissue of male rats leads to concomitant increases of intracellular concentrations of adenosine 3′:5′-monophosphate and of release of both LH and FSH. The stimulatory effect of LH-releasing hormone/FSH-releasing hormone is observed after a lag period of about 90 min and is progressive at later time intervals; a 3-fold stimulation of cAMP accumulation over control is seen after 210 min of incubation. Half-maximal stimulation of cAMP accumulation is observed between 0.1 and 1.0 ng/ml (0.1-1 nM) of LH-releasing hormone/FSH-releasing hormone. In the presence of 10 mM theophylline, the stimulatory effect of LH-releasing hormone/FSH-releasing hormone on cAMP accumulation is similar to that observed in the absence of the inhibitor of cyclic nucleotide phosphodiesterase, indicating that the releasing hormone exerts its effect by specific activation of adenylate cyclase in LH- and FSH-secreting cells rather than by inhibition of cyclic nucleotide phosphodiesterase. Since the release of growth hormone, thyrotropin, prolactin, and adrenocorticotropic hormone is not affected by LH-releasing hormone/FSH-releasing hormone, and since cAMP stimulates the release of all six adenohypophyseal hormones. the observed changes of cAMP concentrations indicate specific stimulation of adenylate cyclase activity in LH-and FSH-secreting cells of the adenohypophysis.

Aldosterone Secretion in Man DISSOCIATION OF RESPONSES TO DOPAMINE AND BROMOCRIPTINE

Abstract: A B S T RA C T This study was desigined to investigate the role of dopaminergic mechanisms in the control of aldosterone secretion in man. Five normal male subjects in metabolic balance at 150 meq sodium/d and 60 meq potassium/d constant intake received the specific dopamine antagonist, metoclopramide, 10 mg i.v. on 2 consecutive d. On the 1st d, the subjects received an infusion of 5% glucose solution (vehicle) from 60 min before to 60 min after metoclopramide administration; on the 2nd d, an infusion of dopamine 4 jig/kg per min was substituted for vehicle. Metoclopramide in the presence of vehicle increased plasma aldosterone concentrations from 2.4±1.1 to a maximum of 17.2±2.8 ng/100 ml (P < 0.01) and serum prolactin concentrations from 7.5±5.0 to a maximum of82.2±8.7 ng/ml (P < 0.01). Dopamine 4 ,ug/kg per min did not alter basal plasma aldosterone concentrations, but blunted the aldosterone responses to metoclopramide significantly; in the presence of dopamine, plasma aldosterone concentrations increased from 3.1±0.5 to 6.2±1.4 ng/100 ml (P < 0.05) in response to metoclopramide. The incremental aldosterone responses to metoclopramide were significantly lower in the presence of dopamine than with vehicle. Dopamine 4 ,ug/kg per min suppressed basal prolactin to <3 ng/ml and inhibited the prolactin responses to metoclopramide; serum prolactin concentrations increased to a maximum of8.5±2.3 ng/ml with metoclopramide in the presence of dopamine. The subjects were studied in the same manner ex