Tuesday, June 29, 2010

Link between Sexual Motivation State and Dopamine Release in the mPOA?

Is an increase in dopamine release in the medial preoptic area (mPOA) specifically related to male physical arousal and sexual behavior or does it have a bigger role in sexual motivation?

Kleitz-Nelson, Dominguez, Cornil & Ball (2010) investigated this question by using the Japanese quail (Coturnix japonica). The male quail does not an have an intromittent organ and therefore does not require an erection to successfully copulate. The researchers collected and measured the dopamine content from extracellular samples from the adult male quails’ mPOA every six minutes before, during and after exposure to a female quail.

What they found was that for male quails that copulated, their levels of extracellular dopamine increased dramatically past baseline levels (BL1-3) when the female quail was introduced (F1-F6) and decreased after the female quail was removed (POST1-POST6). Non-copulators did not exhibit an increase in extracellular dopamine levels.

In addition, for copulators, the researchers did not find any changes in extracellular dopamine levels between sampling periods during which the quails either engaged in the actual mating behavior or not. That is to say, during the sampling period, regardless of whether the male quail was engaging in coitus or not, their levels of extracellular dopamine levels showed increased levels as long as they are in the presence of the female.

The authors thus concluded that the rise in extracellular dopamine in the mPOA is not only involved in erection and ejaculation, as the copulators had high levels of extracellular dopamine regardless of whether they were actually engaging in mating behavior at that moment. And given that the quails do not require an erection for copulation to occur, the evidence suggests strongly that extracellular dopamine in the mPOA is specifically associated with sexual motivation and not just physical arousal.

Kleitz-Nelson, H., Dominguez, J., Cornil, C., & Ball, G. (2010). Is sexual motivational state linked to dopamine release in the medial preoptic area? Behavioral Neuroscience, 124 (2), 300-304 DOI: 10.1037/a0018767

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