Poor Decision Making and Sociability Impairment Following Central Serotonin Reduction in Inducible TPH2-Knockdown...

Area of Science:

• Neuroscience
• Cognitive Science
• Animal Behavior

Background:

• Serotonin is crucial for mental health and socio-cognitive functions.
• Previous studies showed constitutive serotonin depletion did not impair rat cognition in isolation.
• The impact of mild, acute serotonin reduction on cognition remains unclear.

Purpose of the Study:

• To investigate the effects of a mild, acute decrease in brain serotonin on rat cognitive abilities.
• To utilize a novel inducible rat model for controlled serotonin depletion.

Main Methods:

• Developed an inducible rat model with genetic knockdown of tryptophan hydroxylase 2 (TPH2) via doxycycline.
• Achieved a 20% serotonin decrease in the hypothalamus after three weeks of treatment.
• Assessed decision making (Rat Gambling Task), cognitive flexibility, and social recognition memory in TPH2-knockdown (Tph2-kd) and control rats.

Main Results:

• Tph2-kd rats exhibited disadvantageous long-term decision-making (poor decision making).
• Poor decision-making low-serotonin rats showed increased sensitivity to probabilistic discounting and impaired social recognition memory.
• Cognitive flexibility was not affected by the acute serotonin reduction.

Conclusions:

• Acute serotonin reduction specifically amplified cognitive deficits in rats already identified as poor decision-makers.
• Poor social recognition memory was a key characteristic of this subgroup, suggesting its role in their behavioral profile.
• The Tph2-kd model is valuable for studying individual susceptibility to cognitive impairment from mild serotonin variations.