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. 2011 Apr 7;4(4):603–629. doi: 10.3390/ph4040603

Figure 1.

Figure 1

Hypothetic model of the mechanism of action of 5-HT3 receptor agonists on the dorsal raphe nucleus-prefrontal cortex loop. Cortical 5-HT3 receptors seem to be localized both presynaptically on 5-HT neurons and postsynaptically on GABAergic interneurons. Stimulation of dorsal raphe nucleus induces a cortical release of 5-HT. Thus, released 5-HT may target postsynaptic 5-HT3 receptors inducing an activation of GABAergic interneurons. These interneurons inhibit pyramidal cells that reduce 5-HT dorsal raphe neuronal firing rate. 5-HT receptors are represented in yellow except 5-HT3 receptors in orange and ionotropic glutamatergic receptors are represented in red. DRN, dorsal raphe nucleus, mPFC, medial prefrontal cortex, GABA, gamma aminobutyric acid, GLUT, glutamate.