Neurotensin activates GABAergic interneurons in the prefrontal cortex

Area of Science:

• Neuroscience
• Neuropharmacology
• Psychiatry

Background:

• Schizophrenia is linked to prefrontal cortical GABAergic interneuron dysfunction.
• Neurotensin, a peptide transmitter found in dopamine axons, may modulate these interneurons.
• Previous research suggests neurotensin levels may be decreased in schizophrenia.

Purpose of the Study:

• To investigate the role of neurotensin in regulating GABAergic interneurons in the rat prefrontal cortex (PFC).
• To determine if neurotensin's effects are mediated by neurotensin receptor 1 (NTR1).
• To explore neurotensin's involvement in dopamine agonist-induced GABA release in the PFC.

Main Methods:

• In vivo microdialysis in freely moving rats.
• Administration of neurotensin and dopamine agonists into the PFC.
• Use of tetrodotoxin to assess impulse dependency.
• Pharmacological blockade using the NTR1 antagonist SR48692.

Main Results:

• Neurotensin administration increased extracellular GABA levels in the PFC in a concentration-dependent and impulse-dependent manner.
• The effect of neurotensin on GABA was blocked by the NTR1 antagonist SR48692.
• NTR1 was found on GABAergic interneurons, particularly parvalbumin-containing ones.
• Dopamine D2 agonist-induced increases in PFC GABA were blocked by SR48692, suggesting neurotensin release mediates this effect.

Conclusions:

• Neurotensin plays a significant role in regulating prefrontal cortical GABAergic interneurons.
• Neurotensin acts via NTR1 located on interneurons.
• Neurotensin release, stimulated by D2 agonists, contributes to dopamine's regulation of GABA.
• Neurotensin agonists may be a potential adjunct therapy for schizophrenia.