MORPHINE INHIBITS TESTOSTERONE SECRETION FROM RAT LEYDIG CELLS IN VITRO

Testosterone Secretion

Abstract

Objective: To study the effect of morphine on in vitro production of testicular T from un-stimulated or LH stimulated Leydig cells.
Study design: Experimental study.
Place and Duration: Biological and Biomedical Sciences Department, Aga Khan University Karachi.
Materials and Methods: 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 200 ƒÝl 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 £gIU) 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.
Results: 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).
Conclusion: These in vitro results show that the morphine inhibits T secretion directly at the testis level.