The effect of intraperitoneal melatonin supplementation on the release of thyroid hormones and testosterone in rats with hyperthyroid.
OBJECTIVE
Melatonin has a general inhibitory effect on the reproductive system and thyroid functions. Testosterone secretion increases in parallel to thyroid hormones in hyperthyroidism. The aim of this study was to investigate the effects of melatonin application on total T3, T4 and testosterone in hyperthyroid rats.


METHODS
This study was performed on 4 groups each consisted of 6 male Spraque Dawley rats. Control group (G1); sham group (G2); applied 0.5 ml/day of serum physiologic intraperitoneally for 2 weeks, hyperthyroid group (G3); applied 0.3 mg/kg/day thyroxine intraperitoneally for 2 weeks, and hyperthyroid and melatonin supplemented group (G4); applied 0.3 mg/kg/day thyroxine and 3 mg/kg/day melatonin. Blood samples taken by way of decapitation were analysed for total T3, T4 and testosterone by RIA.


RESULTS
Serum total T3 and total testosterone levels were the highest in hyperthyroid group (G3), whereas in hyperthyroid and melatonin supplemented group (G4) were the lowest (P<0.001). Total T4 levels were higher in group 3 than group 1, 2 and 4 (P<0.001).


CONCLUSIONS
Results revealed that melatonin supplementation in hyperthyroidism suppress secretion of thyroid hormones and testosterone secretion.
Mogulkoc
Rasim
R
Selcuk University, Meram Medical School, Department of Physiology, 42080 Konya-Turkey. mogulkoc@selcuk.edu.tr
Baltaci
Abdulkerim Kasim
AK
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D006980:Hyperthyroidism / Q000188:drug therapy* / Q000378:metabolism; D007274:Injections, Intraperitoneal; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013737:Testis / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism*; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D013963:Thyroid Hormones / Q000378:metabolism*
D000975:Antioxidants; D013963:Thyroid Hormones; D013739:Testosterone; D008550:Melatonin