Opposite effects of interleukin-2 and interleukin-4 on GABA-induced inward currents of dialysed Lymnaea neurons.

1. The effects of interleukin-2 (rhIL-2) and interleukin-4 (rhIL-4) were investigated on gamma-aminobutyric acid (GABA)-induced inward currents on isolated, identified neurons of Lymnaea stagnalis L. (Mollusca, Gastropoda) by using a concentration clamp technique. 2. It was shown that the interleukins modified the GABA-induced inward current in an opposite direction: rhIL-2 (2-100 U/ml) decreased the peak value of IGABA in a dose-dependent manner, whereas rhIL-4 (0.2-100 U/ml), on the contrary, potentiated it. Both types of modulation were partially or fully reversible. 3. The reversal potential of IGABA was not shifted by these cytokines. 4. The time-to-peak value and inactivation time constant of the gamma-aminobutyric acid (GABA)-induced current was decreased by rhIL-4. The modulatory effect of rhIL-4 was eliminated after conjugation of this cytokine with its antibody. 5. It appears that cytokines could play a role in regulating the neural excitability through GABA-erg mechanisms.