Oxytocin is a hormone long associated with female reproduction and pregnancy. Scientists, and the wider public, took a greater interest in it when several studies into the monogamous (unusually for small mammals) mating habits of prairie voles, suggested that it may be oxytocin that determines that behaviour, both in males and females.
Today it was reported in the science news Eureka Alert website, that Japanese scientists have found the mechanism by which oxytocin influences male sexual function. Apparently, this includes not only the ability to get erections, but in general sexual activity, and well..horniness. The researchers expressed their hope that their findings could lead to new treatments for male sexual disfunction. Perhaps this will result in something like viagra x 100?
It is already known that spinal regions like the spinal ejaculation generator (SEG) are known to control sexual functions in male rodents. To assess the role of oxytocin in copulatory and ejaculatory responses, the team injected oxytocin into the spine of male rats. The gastrin-releasing peptide or GRP neurons are an important component of the SEG, as they control the lower lumbar region connected to muscles at the base of the penis, thereby controlling erection and ejaculation.
Oxytocin caused an increased sexual activity and neuronal activity in injected animals. More specifically, oxytocin was found to directly activate SEG/GRP neurons via oxytocin receptors, which detect oxytocin, and influence male sexual function in the rat lumbar spinal cord. Using an oxytocin receptor antagonist, which reduces the activity of oxytocin receptors, resulted in a latency and decrease in number of sexual activity and ejaculatory responses in majority of the animals, confirming the importance of oxytocin.
The question remained about the transport of oxytocin, however. Electron microscopy images acquired from slices of the lumbar region ruled out the presence of synaptic vesicles or connections. Upon stimulation of exocytosis ex-vivo, they were able to observe oxytocin transport mediated by a more passive diffusion in extracellular spaces at non-synaptic sites.
Highlighting the importance of the study, Prof Sakamoto remarks, “Now that we have uncovered a novel neural mechanism-the ‘localized volume transmission’ of oxytocin from axons-involved in controlling male sexual function in the spinal cord, we can hope that this may lead to the development of treatments for male sexual dysfunction.”
This study thus presents a completely unprecedented role for oxytocin in male sexual function, in addition to its long-standing “female-centric” role. Learning more about this “love hormone” may indeed help us foster healthier and long-lasting loving relationships!
Professor Sakamoto…hmmm. that name rings a bell. Does anyone else remember the Thomas Dolby one hit wonder – ‘She Blinded Me With Science’ (1982)?