Analysis of the Role of Endogenous Prolactin on Fluid and Sodium Chloride Absorption by the Rat Jejunum

Abstract

Intestinal absorption of fluid and NaCl in rats is significantly decreased after hypophysectomy and increased in rats with pituitary implants. Oestrogen and reserpine significantly stimulate mucosal fluid and NaCl transfer in both normal and adrenalectomized rats, comparable to the effects of administration of prolactin. In intact rats, ergocryptine enhanced intestinal absorption of fluid and NaCl; however, it failed to exert any effects in adrenalectomized rats. Adrenalectomy alone had no adverse effects on intestinal absorption in saline-compensated rats. The administration of corticosterone alone or together with prolactin significantly enhanced intestinal absorption, although the effect of corticosterone alone was more variable. These data strongly suggest that increased endogenous prolactin levels produce stimulatory effects on intestinal absorption of fluid and NaCl by the rat jejunum.

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

“…It has been reported that administration of prolactin stimulates fluid and electrolyte trans¬ port through the rat small intestine (Ramsey & Bern, 1972;Mainoya et al 1974;Mainoya, 1975 ). The results reported here indicate that during the oestrous cycle of the rat, intestinal absorption of fluid and NaCl undergoes changes similar to those reported by Crocker (1971) for the intestine and by Pye & Matty (1968) for the kidney.…”

Control of Ion Transport in Mouse Proximal and Distal Colon by Prolactin

“…In contrast, a decrease in water absorption by PRL in the rat small intestine and colonic epithelium was reported in other studies [6,7]. In these studies, the effects of PRL on water absorption in jejunum [4] and colon [7] were largely dependent on the luminal ion composition and the transport of electrolytes. These results prompted us to study the potential effects of PRL on electrogenic ion transport in mouse colon.…”

“…Although its effects are less clear in mammals, PRL has been shown to increase fluid and NaCl absorption in the rat proximal colon [3]. Increases in endogenous PRL levels after pituitary transplants cause enhanced intestinal absorption of fluid and Na + /Cl -in the rat jejunum, and PRL increased fetomaternal fluid transport across the placental membrane [4,5]. In contrast, a decrease in water absorption by PRL in the rat small intestine and colonic epithelium was reported in other studies [6,7].…”

Prolactin and Osmoregulation in Vertebrates

“…Treatment of rats with high (superphysiological) doses of ovine prolactin produced fluid shifts from intracellular to extracellular fluid compartments, of possible importance in maintaining vascular volume during acute stress [128]; a similar fluid shift from intracellular to extracellular spaces following ovine prolactin treatment, has been reported for the tilapia [111], As with other vertebrate classes discussed above, closer attention is being paid to transport across individual or gans. Intestinal sacs have been used for some time to de monstrate the stimulatory effect of prolactin on Na*, Cl and water absorption [117][118][119][120][121][122]169]. Other experiments de monstrate that prolactin also stimulates intestinal Ca2 transport [53,120] (and bone Ca-'* mobilization [150]); this may be one effect contributing to the hypercalcemic action mentioned above.…”