Acute dopaminergic blockade augments the naloxone-induced LH rise in estrogen-treated postmenopausal women

Serum prolactin is associated with apoptosis in men with human immunodeficiency virus infection

“…The present findings in serum RIA‐PRL and especially in BIO‐PRL concentrations suggest that these HIV‐infected men had a diminished hypothalamic DA tone, as previously suggested, 23 , 24 because their mean basal BIO‐PRL concentration was greater and the RIA‐PRL and BIO‐PRL responses to intravenous metoclopramide were lower than in uninfected men 34 , 35 …”

“…The present findings in serum RIA-PRL and especially in BIO-PRL concentrations suggest that these HIV-infected men had a diminished hypothalamic DA tone, as previously suggested, 23,24 because their mean basal BIO-PRL concentration was greater and the RIA-PRL and BIO-PRL responses to intravenous metoclopramide were lower than in uninfected men. 34,35 The mechanisms controlling the extra-pituitary production of PRL (specifically, in human lymphocytes) are unclear; however, this hormone acts as a comitogen for human T and B cells 12,13 and the intralymphocyte DA concentration is known to downregulate their own proliferation in humans. 20 Furthermore, a temporal decrease in Con-A stimulated lymphocyte proliferation has been described in critically ill patients with low serum PRL concentrations induced by DA infusions.…”

“…One possible explanation is that as apoptosis increased in the HIV-infected men, the decrease in CD4 + T lymphocytes paralleled a diminution in the DA tone of the body (as shown by the lower serum RIA-PRL response to the i.v. metoclopramide) 23,24,35 attempting to maintain PRL synthesis and release as high as possible. 25 At the same time, increasing apoptosis was associated in a positive fashion with the AUC BIO/RIA PRL 120 min, which suggests that augmented apoptosis was paralleled by an increased availability of BIO-over RIA-PRL, which is consistent with the antiapoptotic properties of this hormone.…”

Decreased dopaminergic tone and increased basal bioactive prolactin in men with human immunodeficiency virus infection

“…and the serum kept frozen at − 20°C until duplicate determinations of several hormones were performed. In previous studies in a different population of patients (Parra et al ., 1997a, 1997b) we found that the early PRL response (0–120 minutes) to metoclopramide gave the same but qualitatively better information than the overall response (0–300 min). Accordingly, the area under the PRL curve from 0 to 120 minutes (AUC 120 min) and from 0 to 300 minutes (AUC 300 min) were calculated separately to analyse if the same observation could apply in this type of patients.…”

“…In fact, an increased RIA–PRL response to intravenous metoclopramide has long been interpreted as indirect evidence of an increased endogenous DA tone (Quigley et al ., 1979). In contrast, the diminished RIA and BIO–PRL responses to metoclopramide observed in patients of group 2 could represent the existence of a diminished—but not abolished—hypothalamic DA tone (Parra et al ., 1997b). The finding of a mean basal BIO–PRL concentration higher in group 2 than in group 1 and the lack of serum TSH response to metoclopramide in the former but not in the latter, lend further support to the existence of low DA tone (Scanlon et al ., 1979) in these HIV infected men.…”