Cadmium effects on dopamine turnover and plasma levels of prolactin, GH and ACTH

This paper analyzes possible dopamine (DA) mediated cadmium effects on plasma levels of prolactin, growing hormone (GH) and adrenocorticotropic hormone (ACTH), and if these changes are related to metal accumulation. For that purpose, adult male rats were treated with 50 mg/L of CdCl2 in the drinking water for one month. Plasma levels of prolactin, ACTH and GH were measured by specific double antibody radioimmunoassays. DA was measured by high performance liquid chromatography using electrochemical detection. Cadmium content in the tissues was measured by atomic absorption spectometry with graphite furnace. Analysis was performed by using a T-Student test. Metal exposure increased DA content (34.79+/-3.06 vs. 18.2+/-2.88 pg/mg protein) and decreased its turnover (0.40+/-0.07 vs. 0.75+/-0.06) in posterior hypothalamus. Cadmium also decreased DA turnover in median eminence (0.48+/-0.15 vs. 1.50+/-0.63). Plasma levels of prolactin and GH decreased (2.4+/-0.11 vs. 3.1+/-0.15 ng/mL and 5.37+/-0.05 vs. 9.87+/-1.8 ng/mL respectively), while those of ACTH increased (2.73+/-0.14 vs. 1.7+/-0.16 ng/mL). Cadmium concentration increased in both hypothalamus (4.88+/-0.34 vs. 0.72+/-0.2 microg/g) and pituitary (22.82+/-4.57 vs. 5.02+/-1.25 microg/g) after the metal exposure. These results suggest that cadmium effects on the secretion of these hormones are not mediated by dopamine and might be correlated to the metal accumulation at pituitary level.