Altered anxiety and depression-related behaviour in mice lacking GABAB (2) receptor subunits

Metabotropic GABA_B receptors predominantly function as heterodimers of GABA_B(1) and GABA_B(2) subunits, but GABA_B(1) can also form functional receptors in the absence of GABA_B(2). Mice lacking the GABA_B(1) subunit have altered behavioural responses in tests for anxiety and depression. In these studies, we investigated anxiety and depression in GABA_B(2)-deficient mice. We compared the effects directly with that of genetic deletion of the GABA _B(1) receptor subunit. Both GABA_B(1) and GABA _B(2)-deficient mice were found to be more anxious than wild type in the light-dark box paradigm. In contrast, these mice exhibited an antidepressant-like behaviour in the forced swim test. Taken together, these data suggest that heterodimeric GABA_B(1,2) receptors are required for the normal regulation of emotional behaviour.