Ação da testosterona em modelo de dor aguda pós-operatória em roedores

Abstract

ABSTRACT Rationale and objectives: Testosterone is a steroid hormone that confers male sexual characters and may interfere with pain perception, but to this day little is known about this property. The aim of this study was to verify whether testosterone, by blocking androgen receptors in peripheral tissues, may alter the behavioral response of rats exposed to acute postoperative pain. Method: The animals were subdivided into two groups with 10 rats each (n = 20): F group was treated with an androgen receptor antagonist (Flutamide) at a dose of 50mg/kg/day throughout the experiment and the T group Received no medication. On the 7th day after the start of the experiment all rats were submitted to a plantar incision on the right hind paw. The animals were evaluated for behavioral signs of acute pain before the plantar incision (baseline), two hours after plantar incision, at the 1st, 2nd, 3rd and 7th postoperative day in the tests of non-evoked pain behavior (Guarding Pain), mechanical allodynia (Von Frey) and weight distribution of the hind limbs (Weight Bearing). Results: The plantar incision caused allodynia and significant static disability in the animals. Flutamide treatment increased the perception of pain in the animals on the 2nd, 3rd and 7th postoperative day in the static impairment test, Weight Bearing. In addition, at the 2nd hour after the plantar incision, the animals submitted to Flutamide treatment presented greater unevoked painful behavior, observed by Guarding Pain, and lower paw withdrawal threshold, by the Von Frey test. Conclusions: These results indicate that the lower bioavailability of testosterone contributes to a greater perception of pain in rats in an experimental model of acute postoperative pain.