Cadmium affects the episodic luteinizing hormone secretion in male rats: possible age-dependent effects.
Cadmium affects luteinizing hormone (LH) secretion through unknown mechanisms. The present study was undertaken to assess whether chronic exposure to low concentrations of cadmium may affect the episodic secretion of LH and if these effects are age-dependent. Male rats were given cadmium at a dose of 50 ppm in the drinking water, from day 30 to 60 or from day 60 to 90 of life. Age-matched rats with access to cadmium-free water were used as controls. At the end of the treatment, blood samples were collected every 7 min for 3 h, from 10:30 to 13.30 in conscious, freely moving rats. In control animals, mean serum LH levels and pulse duration increased with age (P < or = 0.001), and pulse frequency and the relative amplitude of LH pulses decreased (P < or = 0.001). Cadmium administration, from day 30 to 60 of life, decreased the pulse frequency and mean half-life of the hormone (P < or = 0.05, P < or = 0.01, respectively). However, no changes in any other parameters studied were observed as compared to the control group. When cadmium was administered from day 60 to 90, mean serum LH levels and the duration of LH pulses decreased (P < or = 0.05), whereas the pulse frequency increased (P < or = 0.05). The absolute and relative amplitude of the LH peaks and the mean half-life of the hormone were not changed after cadmium administration from day 60 to 90. These results indicate that low doses of cadmium change the pulsatile secretion of LH in male rats and that the effect of cadmium on episodic LH release was age-dependent.
Lafuente
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Laboratorio de Toxicología, Facultad de Ciencias, Universidad de Vigo, Campus de Orense, Las Lagunas, Spain. lafuente@uvigo.es
Márquez
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Piquero
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Esquifino
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AI
D000375:Aging / Q000378:metabolism*; D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D006207:Half-Life; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley
D002104:Cadmium; D007986:Luteinizing Hormone