Adenosine inhibits a GABAB receptor-mediated hyperpolarizing postsynaptic potential in neurons of rat septal nuclei.

Intracellular recordings were made from neurons of rat dorsolateral septal nucleus (DLSN), in vitro. Adenosine and 2-chloroadenosine (1-500 microM) hyperpolarized DLSN neurons and blocked the excitatory postsynaptic potential (EPSP) and the late hyperpolarizing potential (LHP) in the presence of bicuculline. Adenosine did not depress the glutamate-induced potential. Bath-application of adenosine depressed the baclofen-induced potential in 60% of the neurons. Adenosine also inhibited the LHP in the remaining 40% of neurons, while it did not depress the baclofen-induced potential in these neurons. These results indicate that adenosine inhibits the EPSP pre-synaptically whereas it inhibits the LHP both pre- and postsynaptically in rat septal nuclei.