Levels, uptake, and release of glycine and glutamate in the rat pontine reticular formation.

In this work we have determined the levels of glycine, glutamate, and other amino acids in the rat pontine reticular formation (PRF), in addition to some properties of the uptake and release of labeled glycine and glutamate in slices of this region. Glutamate was the most concentrated amino acid in the PRF, although its content was about half that of the striatum. Surprisingly, glycine levels in the PRF were 3.2-fold higher than in the striatum, whereas GABA content was similar in both regions. The uptake of both glycine and glutamate by PRF slices was strictly Na(+)-dependent. Their release was stimulated by K(+)-depolarization, but only the release of glycine was Ca(2+)-dependent. These findings suggest that glycine is a strong candidate for a neurotransmitter role in the PRF and that glutamate might also play such a role in this region.