Effect of aluminium on duodenal calcium transport in pregnant and lactating rats treated with bromocriptine

The aim of present work was to study the effect of oral aluminium (Al) overload on intestinal calcium (Ca) absorption in the critical stages of pregnancy and lactation of rats and to find out possible relationships with prolactin (PRL) and 17β-estradiol (E2) circulating levels. Adult female Wistar rats were orally treated from day 1 of pregnancy with 0 (control), or 50 mg elemental Al (as chloride)/kg body weight per day. Ca transport was determined by everted duodenal sacs technique using 2 μCi of 45CaCl2 as flux marker (JCams). Al treatment reduced JCams either in late pregnancy (day 19) or in middle lactation (day 9 postpartum). Oral administration of bromocriptine (BrC), an inhibitor of PRL secretion, at dose of 10 mg/kg body weight given 18 h before JCams measurements were done, produced a significant decrease in the inhibitory effect of Al on JCams, expressed as percent of control, at day 9 of nursing (vehicle: 51 ± 7%, BrC: 28 ± 4%, P < 0.05). A positive correlation between Al effects on JCams and the physiological variations of E2 serum levels along pregnancy and lactation in BrC-treated rats was also found (r2 = 0.277, P = 0.001). We conclude Al could reduce transcellular Ca absorption in the duodenum by interfering with physiological mechanisms of Ca transport partially mediated by serum level increments of E2 and PRL, observed in late pregnancy and mainly during middle lactation of rats.