Hypothalamic KiSS1/GPR54 Gene Expressions and Luteinizing Hormone Plasma Secretion in Morphine Treated Male Rats

Objective The inhibitory effects of Morphine and the stimulatory influence of kisspeptin signaling have been demonstrated on GnRH/LH release. Hypothalamic kisspeptin is involved in relaying the environmental and metabolic information to reproductive axis. In the present study the role of kisspeptin/GPR54 signaling system was investigated on relaying the inhibitory effects of morphine on LH hormone secretion. MaterialsAndMethods : In the experimental present study, fifty five Wistar male rats weighing 230-250g in 11 groups (in each group n=5) received saline, kisspeptin(1nmol), P234(1nmol), morphine(5mg/kg), naloxone (2mg/kg), kisspeptin/P234, morphine/naloxone, kisspeptin/morphine, kisspeptin/naloxone, P234/morphine or P234/naloxone respectively. Blood samples were collected via tail vein. Mean plasma LH concentrations and mean relative KiSS1or GPR54 mRNA levels were determined by RIA and RT-PCR respectively. Results Morphine caused a significant decrease in mean LH concentration, mean relative KiSS1 gene expressions and a non- significant decrease in mean relative GPR54 gene expressions compared to saline. Naloxone caused a significant increase in mean LH concentration and mean relative KiSS1 gene expressions and a non- significant increase in mean relative GPR54 gene expressions compared to saline. Co- administration of kisspeptin/morphine increased significantly mean LH concentration compared to saline or morphine. Co- administration of kisspeptin/morphine decreased significantly mean LH concentration compared to kisspeptin. Co-administration of kisspeptin/naloxone increased significantly mean LH concentration compared to saline or naloxone. Co- administration of P234/morphine decreased mean LH concentration significantly compared to saline. Conclusion Down regulation of Kiss1 gene expression may be partly involved in the mediating the inhibitory effects of morphine on reproductive axis.