Nucleus tractus solitarius: an evaluation by in vivo voltammetry

Area of Science:

• Neuroscience
• Neurochemistry
• Cardiovascular Regulation

Background:

• The nucleus tractus solitarius (NTS) is crucial for cardiovascular regulation.
• Monoamines play a significant role in NTS function.
• Understanding NTS neurochemistry is vital for cardiovascular control research.

Purpose of the Study:

• To pharmacologically characterize in vivo electrochemical signals in the rat NTS.
• To elucidate the neurochemical basis of signals recorded in the NTS.
• To investigate the role of monoamines in NTS cardiovascular regulation.

Main Methods:

• In vivo electrochemical recordings using carbon paste electrodes and linear sweep voltammetry in freely moving rats.
• Semiderivative signal processing to analyze electrochemical data.
• Pharmacological manipulation with tyrosine hydroxylase, dopamine-beta-hydroxylase, and monoamine oxidase inhibitors.
• Tissue assays to confirm neurochemical changes.

Main Results:

• Two distinct peaks were observed: 0.14 V and 0.28 V.
• The 0.14 V peak was reduced by alpha-methyl-p-tyrosine and fusaric acid, suggesting norepinephrine and possibly dopamine.
• The 0.28 V peak was reduced by pargyline and increased by fusaric acid, consistent with 5-HIAA.
• Tissue assays confirmed norepinephrine reduction and altered 5-HIAA levels.

Conclusions:

• The 0.14 V electrochemical signal in the NTS likely represents norepinephrine, with a potential dopamine contribution.
• The 0.28 V signal is identified as 5-HIAA.
• These findings enhance the understanding of monoaminergic neurotransmission in NTS-mediated cardiovascular control.