Infralimbic cortex activation and motivated arousal induce histamine release

Area of Science:

• Neuroscience
• Behavioral Neuroscience

Background:

• Appetitive behaviors require significant behavioral and physiological activation.
• The infralimbic cortex is implicated in regulating motivated behaviors.

Purpose of the Study:

• To investigate the role of histamine neurons, controlled by the infralimbic cortex, in behavioral activation.
• To examine the relationship between infralimbic cortex activity, histamine release, and motivated behaviors.

Main Methods:

• Extracellular histamine and serotonin levels were measured in the medial prefrontal cortex of rats using microdialysis.
• The infralimbic cortex was manipulated using picrotoxin (to excite) and muscimol (to inhibit).
• Behavioral activation was assessed in response to food motivation and tactile stimuli.

Main Results:

• Picrotoxin injection into the infralimbic cortex induced behavioral arousal and increased histamine release, while decreasing serotonin levels.
• Inhibition of the infralimbic cortex with muscimol produced opposite effects on neurotransmitter release.
• Histamine release was specifically correlated with behavioral activation during appetitive (food-seeking) tasks, but not with general arousal (awakening).

Conclusions:

• Histamine neurons regulated by the infralimbic cortex are crucial for generating behavioral activation.
• Histamine release is a key neurochemical event associated with the behavioral activation underlying appetitive behaviors.
• These findings highlight the role of the infralimbic cortex-histamine pathway in motivated, goal-directed actions.