Facilitatory actions of guanidine on synaptic transmission in mammalian brain slices.

Guanidine administration may be beneficial in the treatment of amyotrophic lateral sclerosis and related diseases; however, the actions of guanidine on the mammalian central nervous system have not been investigated. We studied the effects of this compound on neuronal properties and synaptic transmission in isolated slices of guinea pig olfactory cortex using intraand extracellular recording methods. Addition of guanidine to the superfusate (3300 pM) produced the following effects. (a) Excitatory and inhibitory postsynaptic potentials, evoked by stimulation of the lateral olfactory tract, were increased in amplitude and duration; (b) the amplitude and frequency of spontaneously occurring postsynaptic potentials was significantly increased; (c) membrane potential and input resistance remained virtually unchanged; and (d) the duration of the lateral olfactory tract compound action potential was prolonged. These results suggest that guanidine enhances the release of excitatory and inhibitory neurotransmitters in the mammalian cortex and this effect may be beneficial in human central nervous system diseases in which the efficiency of synaptic transmission is reduced.