|A weak first attempt (source)|
The basic paradigm was to house the 'experimental rat' to the 'stimulus rat' (who was scented with almond) for a full day every 4 days. Under these conditions, the experimental rat did not show any preference for the almond-scented stimulus rat later on. However, if the experimental rat was injected with quinpirole, which stimulates dopamine D2 receptors, he did develop a preference for the almond-scented rat. This preference was not sexual in nature. Preference was measured by time spent together, and these guys just wanted to hang out.
|Triana-Del Rio et al., 2011 (figure 1)|
The authors then did a separate experiment where instead of using 'sexually naive' rats as the stimulus rats, they used 'sexually expert' rats. They created these Cassanovas by riling them up with very 'receptive' female rats at least 10 separate times. They refer to this as 'sexual training.' When the sexually expert rats were used as stimulus rats, the experimental rats developed a sexual preference when injected with quinpirole. These experimental rats strongly preferred their almond-scented partners as measured by time spent together, mounting, and 'genital investigation.'
So what does this mean? First of all, even the most drastic change was not permanent, partner preference dissipated after 45 days. And as I mentioned in my SfN summary, this protocol did not have the same effect in female rats. I do not think that the researchers here 'turned a rat gay.' While they did succeed in biasing the preference of the experimental rat for the guy he was housed with, they certainly didn't change the rats sexual preference in a deep or universal way. There is no evidence that the experimental rat preferred males in general over females, just that he really likes the one guy he was hanging out with.
So this study does not really tell us anything about the biological basis of homosexuality, and it certainly does not tell us how to make a gay bomb. The most interesting implication for this study is in the activity of the D2 dopamine receptor, which may be involved in pair-bonding. I would be interested to see what some ex vivo cellular studies revealed about this treatment. Does quinpirole application cause a change in the number or location of the D2 dopamine receptors or the activity of the neuron?
Triana-Del Rio R, Montero-Domínguez F, Cibrian-Llanderal T, Tecamachaltzi-Silvaran MB, Garcia LI, Manzo J, Hernandez ME, & Coria-Avila GA (2011). Same-sex cohabitation under the effects of quinpirole induces a conditioned socio-sexual partner preference in males, but not in female rats. Pharmacology, biochemistry, and behavior, 99 (4), 604-13 PMID: 21704064