Pyramidal Neurons in Rat Prefrontal Cortex Projecting to Ventral Tegmental Area and Dorsal Raphe Nucleus Express 5-HT 2A Receptors

Author: Vzquez-Borsetti Pablo   Corts Roser   Artigas Francesc  

Publisher: Oxford University Press

ISSN: 1460-2199

Source: Cerebral Cortex, Vol.19, Iss.7, 2009-07, pp. : 1678-1686

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Abstract

The prefrontal cortex (PFC) is involved in higher brain functions altered in schizophrenia. Classical antipsychotics modulate cortico-limbic circuits mainly through subcortical D2 receptor blockade, whereas second generation (atypical) antipsychotics preferentially target cortical 5-HT receptors. Anatomical and functional evidence supports a PFC-based control of the brainstem monoaminergic nuclei. Using a combination of retrograde tracing experiments and in situ hybridization we report that a substantial proportion of PFC pyramidal neurons projecting to the dorsal raphe (DR) and/or ventral tegmental area (VTA) express 5-HT2A receptors. Cholera-toxin B application into the DR and the VTA retrogradely labeled projection neurons in the medial PFC (mPFC) and in orbitofrontal cortex (OFC). In situ hybridization of 5-HT2A receptor mRNA in the same tissue sections labeled a large neuronal population in mPFC and OFC. The percentage of DR-projecting neurons expressing 5-HT2A receptor mRNA was 60% in mPFC and 75% in OFC (n 3). Equivalent values for VTA-projecting neurons were 55% in both mPFC and ventral OFC. Thus, 5-HT2A receptor activation/blockade in PFC may have downstream effects on dopaminergic and serotonergic systems via direct descending pathways. Atypical antipsychotics may distally modulate monoaminergic cells through PFC 5-HT2A receptor blockade, presumably decreasing the activity of neurons receiving direct cortical inputs.

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