Glutamate as a neural factor for the ex vivo release of catecholamines from the rabbit hippocampus

Abstract

The aim of the research was to confirm the hypothesis about the direct influence of different concentrations of glutamate (Glu; 5, 50 and 200 μM) on the release of catecholamines (CA’s) from hippocampal slices incubated for 90 min. The hippocampus is the central structure of the motivational system and, along with the hypothalamus, amygdala, and medial prefrontal cortex (mPFC), is responsible for memory, learning, and the initiation and course of the reaction to stressoric factors. In our research, we focused on the direct effect of different Glu concentrations on CA release without the involvement of other neural cerebral structures and humoral responses. The effect of Glu added to the incubation fluid was found to be inconsistent. When added at the lowest concentration, Glu inhibited the release of CA from the incubated slices, and at higher concentrations tended to increase the release of CA. Notably, Glu significantly increased the release of epinephrine (E) from incubated slices of the hippocampus. These effects may suggest that physiological concentrations of Glu inhibit CA release from hippocampal neurons in vitro and therefore enhance its excitatory effects in vivo.