Basal prolactin concentrations in 357 patients with renal disease of defined pathology have been compared with those in 210 control subjects. Elevated prolactin concentrations were found in 113 renal patients (32%) including 53 patients in whom elevated concentrations were possibly attributable to drug therapy. In the remaining 60 patients who had hyperprolactinaemia not attributable to drugs, elevated concentrations (P less than 0.005) were found exclusively in patients with impaired renal function. A significant correlation was observed between prolactin and creatinine concentrations in these patients (r = 0.45 P less than 0.005) and prolactin reverted towards normal after successful renal transplantation. A significant arteriovenous prolactin concentration difference across the kidney (mean 16% range 8-29% P less than 0.02) was found in seven patients with non-renal non-endocrine disease. It is concluded that the hyperprolactinaemia found commonly in patients with impaired renal function is only partly attributable to drug therapy. The positive correlation between prolactin and creatinine reversion of prolactin towards normal after successful transplantation and arteriovenous hormone concentration differences across the normal kidney suggests that the kidney has a important role in prolactin metabolism. Abnormal regulation of prolactin secretion in renal failure may also be involved.
Parathyroid hormone related protein (PTHrP) is an important humoral factor in hypercalcaemia of malignancy. In addition there is increasing evidence that this peptide has a physiological role in fetal development, especially in cellular growth and differentiation. Both in-situ hybridization and immunohistochemistry were used together and for the first time to identify sites of PTHrP gene expression and peptide in fetal and extra-embryonic tissues of first trimester human pregnancy. PTHrP mRNA and peptide were identified in the avascular amnion and the syncytiotrophoblast while mRNA alone was expressed in the cytotrophoblast. Its expression in these extra-embryonic tissues is consistent with postulated roles for PTHrP in implantation, relaxation of endometrial muscle and regulation of vascular tone. Expression of both mRNA and peptide occurred in endo-, meso- and ectodermal structures of the fetus, consistent with local production of the peptide rather than cellular uptake from amniotic fluid and supporting a role for PTHrP in cellular growth and differentiation.
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