Glycine and GABA as inhibitory transmitters in the medullary reticular formation stStudies involving intra- and extra-cellular recording

Summary

Studies involving intracellular recording during extracellular drug administration have revealed that both glycine and GABA hyperpolarize and increase the membrane conductance of reticulospinal neurones, glycine usually being more effective than GABA. The inhibition of firing of some medullary reticular neurones produced by stimulating the ventrolateral area of the spinal cord (where reticulospinal axons lie) is blocked by strychnine, which blocks the depression by glycine without affecting that by GABA. Such inhibition is not reduced by bicuculline or picrotoxin in concentrations which block the action of GABA, but do not affect that of glycine. The synaptic inhibition of other reticular neurones is blocked by bicuculline or picrotoxin, but not by strychnine. Thus, both glycine and GABA are likely to be inhibitory transmitters in the medullary reticular formation, possibly released from axon collaterals of two different populations of inhibitory reticulospinal neurones.