the data from both sets of neurons were combined and showed that 1–2 μM dynorphin significantly decreased IPSPs to 79 ± 4% of control (n = 10; F (2,9) = 14.43). Addition of ethanol significantly increased IPSPs to 104 ± 6% of pre-dynorphin level (n = 10; Fig. 3B), reversing the dynorphin effect. The net ethanol effect relative to dynorphin levels (dynorphin values being control values) was a 32 ± 6% increase of IPSP amplitude, and the magnitude of this increase was significantly dampened relative to ethanol application in the absence of dynorphin (unpaired t-test: t = 2.972, df = 15). In addition, the paired-pulse ratio was increased by 1–2 μM dynorphin to 125 ± 8% of control and significantly reversed to 96 ± 10% of control by subsequent addition of ethanol (n = 9; F(2,8) = 4.37; not shown), a net 23 ± 7% decrease elicited by ethanol relative to dynorphin values. These data confirm that dynorphin and ethanol interact at a presynaptic site to differentially affect GABA release and modulate inhibitory transmission.
