EFFECTS OF ACUTE AND SUBCHRONIC CADMIUM ADMINISTRATION ON PITUITARY-HORMONE SECRETION IN RAT

Cadmium administration is known to be followed by deleterious effects on the endocrine system although its action mechanism is not well unde rstood. The purpose of this study was to determine, in vivo, the effec ts of acute and/or subchronic cadmium chloride administration (6 mg/kg or 4 mg/kg/day during 14 days) on prolactin, luteinizing hormone (LH) , follicle stimulating hormone (FSH), growth hormone (GH) and thyroid stimulating hormone (TSH) secretion in adult male rats. Six h after a single injection of CdCl2, a diminution of plasma levels of prolactin (4.52 +/- 0.53 vs. 16.2 +/- 2.7 ng/mL, p < 0.01), GH (3.39 +/- 0.43 vs . 6.71 +/- 1.30, ng/mL, p < 0.01), TSH (2.76 +/- 0.64 vs. 7.65 +/- 1.1 5 ng/mL, p < 0.01) and LH (4.1 +/- 1.3 vs. 5.18 +/- 0.28, p < 0.05) wa s observed, where as plasma FSH levels did not change. On the other ha nd, subchronic cadmium chloride administration for 14 days, increased plasma levels of GH (13.39 +/- 2.74 vs. 6.71 +/- 1.3 ng/mL, p < 0.05), TSH (27.8 +/- 4.42 vs. 6.65 +/- 1.15 ng/mL, p < 0.001), LH (11.1 +/- 1.3 vs. 5.18 +/- 0.28 ng/mL, p < 0.001) and FSH (53.16 +/- 3.66 vs. 12 .51 +/- 1.45, p < 0.001), whereas plasma prolactin levels decreased (6 .86 +/- 1.38 vs. 16.2 +/- 2.7 ng/mL, p < 0.01). In animals subchronica lly treated with CdCl2, body weight gain was lower than in control rat s (p < 0.001). The present findings suggest that acute and subchronic cadmium administration modify pituitary hormone secretion differential ly and specifically.