ABSTRACT
To study the effect of morphine on in vitro production of testicular T from un-stimulated or LH stimulated Leydig cells. Experimental study. Biological and Biomedical Sciences Department, Aga Khan University Karachi. De-capsulated testes from two rats were subjected to enzymatic dispersion for each experiment. Cells were pre-incubated in the incubation medium to remove endogenous Testosterone Thereafter, 80K cells were used for each treatment in 2001 of suspension. Incubation medium contained either no treatment [control] or different concentrations of morphine [5x10-5 -10-9 M]. Leydig cells were also incubated with different doses of LH [16-500 ?IU] and morphine. Naloxone, an opioid receptor antagonist [10-6 M], was used to determine if morphine induced effects on the Leydig cells could be reversed. Incubations were carried out for three hours in a shaking water bath at 340C. Reaction was stopped by placing the tubes in a water bath at 600C, and thereafter the tubes were transferred to a tray containing ice before freezing. Testosterone was measured directly in the incubation medium by radioimmunoassay. Morphine reduced Testosterone production from Leydig cells at all concentrations tested [p<0.01]. There was a dose dependent response to LH stimulation by the Leydig cells and testosterone levels were significantly different from control [p<0.01] and incubation with morphine in the presence of LH significantly reduced T levels [p<0.01]. Inhibition of opioid receptors with naloxone significantly attenuated morphine induced inhibition of T [p<0.01]. These in vitro results show that the morphine inhibits T secretion directly at the testis level