Influence of Reproductive State on Intestinal Fluid and Ion Transport by the Rat Jejunum, in Relation to the Possible Contribution of Prolactin

Abstract

Mucosal fluid, sodium and chloride transfer by the rat jejunum was higher at pro-oestrus and oestrus than at dioestrus. Prolactin enhanced intestinal absorption in dioestrous but not in oestrous rats. Ovariectomy had no significant effect on fluid and sodium absorption but resulted in increased chloride absorption. Oestrogen treatment, however, stimulated fluid and sodium transport without affecting chloride absorption in ovariectomized rats. In contrast, progesterone had no influence on fluid and sodium transport but inhibited chloride absorption. Intestinal absorption of fluid, sodium chloride, potassium, calcium and magnesium was significantly increased during pregnancy and lactation. The limited effect of 2-Br-alpha-ergocryptine in depressing intestinal absorption of fluid and NaCl in both pregnant and lactating rats suggests that hormones other than prolactin are also involved. Lactating rats not suckled for 24 h, or subjected to reduction in the number of pups from eight to three, did not show major changes in intestinal absorption of fluid and NaCl. The present data suggest that increases in intestinal transport during oestrus, pregnancy and lactation are attributable to hormonal changes to which prolactin may make an important contribution.

Hepcidin and 1,25(OH)2D3effectively restore Ca2+transport in β-thalassemic mice: reciprocal phenomenon of Fe2+and Ca2+absorption

“…Although normal female mice exhibited greater duodenal active calcium transport consistent with that reported previously (40), presumably because of the stimulatory effect of estrogen on calcium absorption (8), this sex difference was not observed in thalassemic mice. Indeed, in female BKO mice, the thalassemia-associated impairment of calcium absorption could not be explained simply by decreases in the secretion of ovarian hormones since the plasma levels of estrogen were slightly reduced and progesterone, despite a substantial decrease in circulating level, reportedly had no significant effect on intestinal calcium transport (26,39). Consistently, estrogen supplement could not alleviate the thalassemia-associated impairment of calcium transport (Fig.…”

Active Ion Transport in Dog Tongue: A Possible Role in Taste

“…This is about the Na+ concentration in saliva secreted at basal flow rates (10). It is also approximately the recognition threshold for salt taste in humans adapted to saliva (11). It is conceivable that normal salivary secretions maintain a transepithelial potential close to zero and that the salt taste response coincides with positive potential changes.…”

Proliferation and mRNA expression of absorptive villous cell markers and mineral transporters in prolactin‐exposed IEC‐6 intestinal crypt cells

“…In contrast, PRL was found to suppress the mRNA expression of some calcium, phosphate and magnesium transport‐related genes. Under normal conditions, pregnancy and lactation markedly enhanced the intestinal absorption of calcium, phosphate and magnesium, which predominantly occurred in the villous tip of the small intestine . On the other hand, the intestinal crypts served to secrete fluid and replace shed villous cells .…”

“…Besides the major nutrients such as monosaccharides and amino acids, the intestinal absorption of water and several essential minerals, e.g. calcium, magnesium and phosphate, was also stimulated during these reproductive periods . Previous investigations clearly showed that the lactogenic hormone and versatile growth factor, prolactin (PRL), was also the principal ion regulatory and calciotropic hormone during pregnancy and lactation .…”

“…[3][4][5][6] Previous investigations clearly showed that the lactogenic hormone and versatile growth factor, prolactin (PRL), was also the principal ion regulatory and calciotropic hormone during pregnancy and lactation. 3,7 Inasmuch as most ion regulatory actions of PRL in several epithelia, for example, endometrium and renal tubule, are mediated by the PRL-enhanced transporter activity, 8,9 the direct PRL effect on the intestinal mineral absorption is also believed to solely result from the upregulation and/or enhanced activity of specific transporters in the absorptive villous cells. 6,10 We recently demonstrated that PRL could upregulate calcium transporter expression in the rat intestinal absorptive cells.…”