Noradrenaline modulates the release of [14C]glutamate from dentate but not from CA1/CA3 slices of rat hippocampus.

The modulation of the release of [14C]glutamate by noradrenaline (NA) was investigated in slices prepared from the dentate gyrus and from the CA1/CA3 area of the hippocampus. In dentate, but not in CA1/CA3 slices, NA significantly enhanced K+-induced Ca2+-dependent release, and this effect was mimicked by clonidine and isoprenaline, but not by phenylephrine. The enhancement of release by NA was antagonised by propranolol, but not by yohimbine or phentolamine. These results suggest that NA does not modulate the release of glutamate in CA1/CA3, but does so in the dentate gyrus, probably by acting on presynaptically-located beta receptors.