Allopregnanolone, a neuroactive metabolite of progesterone, restrains oxytocin neurons by enhancing the effectiveness of GABA synapses, but also induces opioid inhibition. Dopamine neurons in the ...

Opioids are known to target the VTA; previous experiments had shown that μ-opioid agonists alter GABA-releasing synapses and reduce inhibitory synaptic transmission in VTA dopamine neurons.

He said neuroscience researchers have long hypothesized that these synapses might form because of a release of GABA and the corresponding sensing activity between two neurons in proximity.