Optogenetic Stimulation of Novel Tph2-Cre Rats Advances Insight into Serotonin's Role in Locomotion, Reinforcement,...

Area of Science:

• Neuroscience
• Behavioral Science
• Genetics

Background:

• Serotonin modulates brain networks controlling motivation and responses to stimuli.
• Serotonin system dysfunction is implicated in psychiatric disorders like OCD.
• Methodological challenges limit understanding serotonin's behavioral functions.

Purpose of the Study:

• To develop and validate novel Tph2-Cre rats for studying serotonin.
• To investigate serotonin's role in motor, compulsive, and reinforced behaviors using optogenetics.
• To explore sex differences in serotonin's behavioral effects.

Main Methods:

• Development and validation of Tph2-Cre rats.
• Optogenetic stimulation of dorsal raphe nucleus serotonin neurons.
• Assessment of motor, aversion, place preference, and compulsive behaviors.
• Validation of optogenetic serotonin release via fast-scan cyclic voltammetry.

Main Results:

• Optogenetic serotonin neuron stimulation did not initiate locomotion or alter aversion-induced locomotion.
• Stimulation did not elicit place preference or affect compulsive behavior.
• Serotonin neuron stimulation sustained ongoing locomotion and reinforced operant lever pressing.
• Reinforcement was exacerbated by food restriction, indicating state-dependent effects.

Conclusions:

• Novel Tph2-Cre rats provide a valuable tool for serotonin research.
• Brainwide serotonin release has mild behavioral effects, particularly in the absence of natural rewards.
• Serotonin's influence on behavior is modulated by physiological state.