Effects of Oral Cadmium Exposure through Puberty on Plasma Prolactin and Gonadotropin Levels and Amino Acid Contents in Various Brain Areas in Pubertal Male Rats

This work was undertaken to analyze if the effects of oral cadmium exposure through puberty, on plasma prolactin and gonadotropin levels are mediated by changes in amino acid contents in various brain areas in male rats. The contents of glutamate, glutamine, aspartate, GABA and taurine in the median eminence, anterior, mediobasal and posterior hypothalamus and prefrontal cortex in pubertal male rats exposed to 50 ppm of cadmium chloride (CdCl 2) in the drinking water for 1 month (through puberty) were measured by high performance liquid chromatography (HPLC). Plasma prolactin, LH and FSH levels were measured by specific RIA methodology. Plasma prolactin levels decreased after cadmium exposure, whereas plasma levels of LH and FSH were not changed by the metal administration. After cadmium exposure, both glutamine and glutamate contents decreased in the median eminence and in anterior and posterior hypothalamus. Metal exposure also decreased aspartate content in anterior and posterior hypothalamus, but increased it in prefrontal cortex. GABA content decreased in any studied brain region after cadmium administration. Besides, the metal decreased taurine content in the median eminence, anterior and posterior hypothalamus and in prefrontal cortex. The results suggest that cadmium effects on plasma prolactin levels may be partially explained by the changes in aspartate, glutamate or taurine contents, but not by the decrease in GABA content in the brain regions studied.