Hyperprolactinemia in asymptomatic patients is related to high molecular weight posttranslational variants or glycosylated forms.

Circulating human Prolactin (PRL) exists in different variants related to posttranslational modifications, dimerization or association with other serum proteins. Compared to monomeric prolactin these variants usually have little or no biologic activity and include BigBig (BB PRL), Big (B PRL), and Glycosylated forms (G PRL). The aim of the present study was to assess levels of BB PRL, B PRL, little PRL (L PRL) and G PRL in hyperprolactinemic patients with no menstrual alterations or galactorrhea.

Cholinergic modulation of GH secretion in acromegalic patients before and after pituitary surgery.

Cholinergic neurotransmission exerts a physiological control on GH secretion. Pirenzepine (Pz), an antagonist of muscarinic receptors, by enhancing hypothalamic somatostatin release, inhibits stimulated GH secretion in normal subjects but not in acromegalic patients. To address the hypothesis that a feedback effect of GH hypersecretion can be involved in this condition, GH responses to GHRH 1-29, 1 microgram/kg iv, with and without administration of Pz, 40 mg iv before tests, were investigated in eight acromegalic patients, before and 20-30 days after transsphenoidal adenomectomy.

Effect of an antiestrogen on the testicular response to acute and chronic administration of hCG in normal and hypogonadotropic hypogonadic men: tamoxifen and testicular response to hCG.

The effect of the antiestrogen tamoxifen (Tx) on the acute and chronic hCG administration was evaluated in patients with hypogonadotropic hypogonadism (HH) and in normal men. An hCG test (5000 IU hCG) was performed before, after two months of hCG administration (2000 IU hCG three times weekly) and after two months of hCG + Tx (2000 IU hCG three times weekly plus 20 mg/day of tamoxifen). Blood samples were obtained before and following 24 and 72 h of every test to determine T, E, 17OHP and SHBG.

Effects of pirenzepine, bromocriptine and their association on basal and GHRH- and TRH-induced GH secretion in acromegaly.

In order to ascertain if pirenzepine (Pz), an antimuscarinic drug, could inhibit GH secretion in acromegaly, 8 patients were submitted to 3 successive treatment courses of 9 days each: Pz, bromocriptine (BRC) and Pz plus BRC. No change in basal levels of GH after Pz administration was seen, but its reduction (p less than 0.05) by BRC was observed.