The beta-lactam antibiotics, penicillin-G and cefoselis have different mechanisms and sites of action at GABA(A) receptors.

The action of the beta-lactam antibiotics, penicillin-G (PCG) and cefoselis (CFSL) on GABA(A) receptors (GABA(A)-R) was investigated using the two-electrode voltage clamp technique and Xenopus oocyte expressed murine GABA(A)-R. Murine GABA(A)-Rs were expressed in Xenopus oocytes by injecting cRNA that encoded for each subunit (alpha1, beta2, and gamma2) and the effects of PCG and CFSL on the alpha1beta2gamma2s subunit receptors were examined using two-electrode voltage clamp. Using the alpha1beta2gamma2s GABA(A)-R, PCG and CFSL inhibited GABA-induced currents in a concentration-dependent manner, with IC(50)s of 557.