Role of central dopaminergic system in premature ejaculation produced by elevated thyroid hormone levels

In our study we aimed to investigate the role of central dopaminergic system by administration of preferential D3 agonist 7-OH-DPAT in premature ejaculation produced byelevated thyroid hormone levels.A total of 16 adult male Wistar rats weighing 300 to 350 gm were used in the study. At the beginning of the study the animals were separated randomly into two groups. Eigth ratswere operated as a control group after subcutan injection of %0.9 NaCl and eigth rats were administered subcutaneously L-thyroxine (T4) for 14 days to induce moderate hyperthyroidism. Following the day after the last injection operations were performed. Rats were anesthetized by intraperitoneal injection of urethane for 1.2 gm/kg body weight. Left cerebral ventricle was cannulated stereotaxically coordinates according to Paxinos and Watson?s (1998) rat brain atlas. Rats underwent seminal vesicle (SV) catheterization and bulbospongiosus (BS) muscle dissection. Electromyographic (EMG) recordings of BSmuscles and SV pressure measurements were performed in all groups before and after administration of 20 micg 7-OH-DPAT intracerebroventricularly.The time interval between 7-OH-DPAT administration and first ejaculation were significantly reduced in hyperthyroid rat group (p= 0,0065). Maximum amplitude of the seminal vesicle pressure values in hyperthyroidism group compared with the control group revealed a statistically significant difference (p=0,0053). In hyperthyroidism group, time interval between the contraction of the seminal vesicle and bulbospongiosus musclecontraction were significantly shorter than control group (p=0,0187). All of the other results measured in hyperthyroidism and control group did not differ significantly from each other.We propose that D3 receptors may have a key role in ejaculation and thyroid hormoneincrease related premature ejaculation. Further studies are needed to clarify this issue.