Comparison of the Effect of Morphine Alone and with Naloxone on Testicular Morphology in Rats

Morphine is an analgesic drug from the opium family that directly affects central nervous system
(CNS) to reduce pain. Naloxone is a pure opioid antagonist that eliminates their respiratory suppressive effects in
CNS. The aim of present study was to compare the effect of morphine on testes, and serum level of cholesterol
and testosterone in male rats.
Methods: In this experimental study, 18 mature male Wistar rats were selected, and randomly divided in 3 equal
groups. The groups received normal saline, morphine alone (5 mg/kg), or combination of morphine (5 mg/kg)
and naloxone (0.4 mg/kg) subcutaneously 4 days in week for 7 weeks. After one week, the histological structure
of testes was studied microscopically, and serum levels of cholesterol and testosterone were determined and
compared between the groups.
Findings: In histology, degeneration of some seminipherous tubules and increase of distance between them was
seen in morphine group; these changes were not seen in morphine-naloxone and control groups. There was not
any significant difference between the groups in terms of serum level of cholesterol and testosterone.
Conclusion: Our study suggests that morphine can result in changes in the structure of the testes but the effect of
morphine-naloxone on rats was only changes in body weight.