Cadmium as an endocrine disruptor: Correlation with anterior pituitary redox and circadian clock mechanisms and prevention by melatonin

Oct 23, 2012Free radical biology & medicine

Cadmium’s link to hormone disruption, daily body rhythms, and oxidative stress in the pituitary, and how melatonin may prevent it

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Cadmium (Cd) disrupted the daily rhythm of prolactin production in male Wistar rats at a low dose of 5 ppm.

Cadmium increased the expression of the prolactin gene and circulating prolactin levels during the early photophase, indicating disrupted rhythmicity.
Lipid peroxidation and redox enzyme expression in the pituitary were elevated following cadmium treatment.
Melatonin treatment reduced the adverse effects of cadmium on prolactin synthesis and release, as well as lipid peroxidation.
Cadmium exposure suppressed daily rhythms of several circadian clock genes, including Clock, Bmal1, Per1, Per2, Cry1, and Cry2.
Co-administration of melatonin restored rhythmicity in Clock and Bmal1 expression, while altering the timing of other circadian genes.
Melatonin also mitigated the impact of cadmium on the 24-hour rhythms of circulating prolactin, luteinizing hormone, thyrotropin, and corticosterone.

AI simplified

To examine the effect of a low dose of cadmium (Cd) as an endocrine disruptor, male Wistar rats received CdCl2 (5ppm Cd) in drinking water or drinking water alone. After 1 month, the rats were euthanized at one of six time intervals around the clock and the 24-h pattern of adenohypophysial prolactin (PRL) synthesis and release, lipid peroxidation, and redox enzyme and metallothionein (MT) gene expression was examined. Cd suppressed 24-h rhythmicity in expression of the PRL gene and in circulating PRL by increasing them at early photophase only, in correlation with an augmented pituitary lipid peroxidation and redox enzyme expression. CdCl2 treatment effectively disrupted the 24-h variation in expression of every pituitary parameter tested except for MT-3. In a second experiment the effect of melatonin (3μg/ml in drinking water) was assessed at early photophase, the time of maximal endocrine-disrupting effect of Cd. Melatonin treatment blunted the effect of Cd on PRL synthesis and release, decreased Cd-induced lipid peroxidation, and counteracted the effect of Cd on expression of most redox enzymes. A third experiment was performed to examine whether melatonin could counteract Cd-induced changes in the 24-h pattern of pituitary circadian clock gene expression and plasma PRL, luteinizing hormone (LH), thyrotropin (TSH), and corticosterone levels. Rats receiving CdCl2 exhibited a suppressed daily rhythm of Clock expression and a significant disruption in daily rhythms of pituitary Bmal1, Per1, Per2, Cry1, and Cry2. The coadministration of melatonin restored rhythmicity in Clock and Bmal1 expression but shifted the maxima in pituitary Per1, Cry1, and Cry2 expression to the scotophase. Melatonin also counteracted the effect of Cd on 24-h rhythmicity of circulating PRL, LH, TSH, and corticosterone. The results highlight the occurrence of a significant endocrine disruptor effect of a low dose of Cd. Generally melatonin counteracted the effects of Cd and ameliorated partially the circadian disruption caused by the pollutant.

Full Text

Full text is available at the source.

View full text (XML) ↗View full text ↗

Cadmium as an endocrine disruptor: Correlation with anterior pituitary redox and circadian clock mechanisms and prevention by melatonin

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief