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Effect of exogenous melatonin on the secretion of testosterone concentration in rhesus monkeys (Macaca mulatta)

. Ghulam Jaffar Kanhar, Samiullah Soomro, Amjad Ali Maitlo, Inam Ali Larik, Sajjad Ali Larik, Waheed Ali Mirbahar, Muhammad Ashraf Sial and Roshan Ali Jamali


Abstract

Background: The impacts of melatonin (18 mg) were explored on testosterone concentration in male goat whereas testosterone amount was inspected in treated and untreated groups. It has been shown that the plasma FSH and LH concentrations increased on short days and decreased on long days, and that a corresponding cycle existed in the plasma concentration. The average value, basal level and numeral value of peaks of testosterone increased, by implantation of melatonin in rams.

Objectives: This study has been carried out on rhesus monkeys (Macaca mulatta) to examine the effect of exogenous melatonin on testosterone concentration (ng/mL).

Methodology: At the intervals of 15 minute sequential blood samples were collected in hepranized needles for a period of 2:45 hours and these samples were centrifuged at 3000rpm for 10 minute immediately. Melatonin single dose (5mg) given orally to four rhesus monkeys to examine the effect of melatonin on plasma testosterone concentration (ng/mL).

Results: The highest mean testosterone  concentration was observed in the segment from 15 to 45 minutes and this changing (increase) in plasma testosterone concentration was not significantly higher compared to that of before treatment segment (P>0.50). Last segment 105 minutes to 120 minutes compared to segment 15 to 45 minutes showed highly considerable change (decrease) in plasma testosterone  concentration (P< 0.01). After this there was gradual decrease in testosterone concentration from 5.14±2.27 to 3.95±1.39 ng/mL.

Conclusion: Present study supports that melatonin sharply increases in testosterone concentrations for short time and then starts decreasing.

Index Terms: Testosterone, Exogenous, Melatonin, Macaca mulatta, Concentration.

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