MK-801 interaction with the 5-HT transporter: a real-time study in brain slices using fast cyclic voltammetry

Area of Science:

• Neuroscience
• Pharmacology
• Neurochemistry

Background:

• Serotonin (5-HT) plays a crucial role in regulating mood and behavior.
• N-methyl-D-aspartate (NMDA) receptors are implicated in various neurological processes.
• Understanding the interaction between NMDA receptors and 5-HT release is vital for developing new therapeutics.

Purpose of the Study:

• To compare the effects of a noncompetitive NMDA receptor antagonist, dizocilpine ((+)-MK-801), and a competitive NMDA antagonist, CPP, on electrically evoked 5-HT release.
• To investigate the role of NMDA receptors in the modulation of 5-HT release in specific brain regions (SNr and DRN).
• To explore potential interactions between MK-801, fluvoxamine, and 5-HT release.

Main Methods:

• Utilized fast cyclic voltammetry (FCV) to measure electrically evoked 5-HT release in brain slices.
• Administered MK-801 and CPP to substantia nigra pars reticulata (SNr) and dorsal raphe nucleus (DRN) slices.
• Assessed the effects of MK-801 and fluvoxamine on 5-HT release, including pre-exposure and co-administration studies.

Main Results:

• MK-801 concentration-dependently potentiated 5-HT release in the SNr and DRN.
• CPP and NMDA had no significant effect on electrically evoked 5-HT release.
• MK-801 and fluvoxamine both potentiated 5-HT release, with MK-801 inhibiting fluvoxamine's enhancing effect.
• MK-801 and fluvoxamine administration significantly increased T1/2 values for 5-HT release.

Conclusions:

• The potentiation of 5-HT release by MK-801 and the lack of effect by CPP or NMDA suggest NMDA receptors are not involved in modulating 5-HT release.
• MK-801 and fluvoxamine may interact at the level of the 5-HT transporter, influencing 5-HT release.
• These findings contribute to understanding the complex neurochemical pathways involved in serotonin regulation.