In the ventral tegmental area (VTA), progestins facilitate lordosis via rapid actions at membrane dopamine Type 1-like (D 1 ) and/or GABA A receptors (GBRs), rather than via cognate, intracellular progestin receptors. Downstream signal transduction pathways involved in these effects were investigated using lordosis as a bioassay. If progestins' actions at D 1 and/or GBRs in the VTA require activation of G-proteins, adenylyl cyclase, cyclic AMP-dependent protein kinase A (PKA), phospholipase C (PLC), and/or PKC, then pharmacologically blocking these pathways would be expected to attenuate progestin-facilitated lordosis and its enhancement by D 1 and GBR activity. Ovariectomized, estradiol-primed rats were infused first with vehicle or signal transduction inhibitor, and second with vehicle, a D 1 or GBR agonist, and then with vehicle or progestins to the VTA. Rats were tested for lordosis following infusions. Results indicated that initiation of G-proteins, adenylyl cyclase, PKA, PLC, or PKC in the VTA is required for rapid effects of progestins through D 1 and/ or GBRs to facilitate lordosis. As well, progestins' actions at n-methyl-d-aspartate receptors (NMDARs) may modulate activity at D 1 and/or GBRs and mitogen activated protein kinase may be a common signaling pathway. Findings from a microarray study demonstrated that there was upregulation of genes associated with steroid metabolism, GBRs, D 1 , NMDARs and signal transduction factors in the midbrain VTA of naturally-receptive mated compared to non-mated rats. Thus, in the VTA, progestins have rapid membrane-mediated actions via D 1 , GBRs, NMDARs and their downstream signal transduction pathways.