Postnatal cocaine exposure affects neonatal passive avoidance performance and cholinergic development in rats

Area of Science:

• Neuroscience
• Developmental Toxicology
• Neuropharmacology

Background:

• Neonatal exposure to psychostimulants like cocaine can impact neurodevelopment.
• Cholinergic systems are crucial for learning and memory processes.
• The effects of early-life cocaine exposure on the developing cholinergic system are not fully understood.

Purpose of the Study:

• To investigate the long-term effects of neonatal cocaine exposure on learning and memory in Wistar rats.
• To examine the impact of early-life cocaine exposure on cholinergic system integrity in the developing brain.

Main Methods:

• Wistar rat pups were administered cocaine hydrochloride (25 mg/kg) or saline subcutaneously from postnatal days 1-11.
• A passive avoidance task (step-off response with foot-shock) was used to assess learning and memory on postnatal days 12 (acquisition) and 13 (retention).
• Choline acetyltransferase (ChAT) enzymatic activity and neuronal immunoreactivity were analyzed in forebrain structures on postnatal day 13.

Main Results:

• Cocaine-treated rats exhibited slight deficits in the latency to step-off during acquisition.
• A generalized increase in trials to criterion was observed in the retention phase for cocaine-exposed rats.
• A decrease in cholinergic enzyme activity was found specifically in the septum of cocaine-treated subjects.
• Other basal forebrain cholinergic regions remained unaffected by neonatal cocaine exposure.

Conclusions:

• Neonatal cocaine exposure in Wistar rats leads to subtle but measurable deficits in passive avoidance learning and memory.
• The developing cholinergic system, particularly in the septum, is vulnerable to cocaine's neurotoxic effects during early life.
• These findings highlight the potential for long-term neurobiological consequences of early-life psychostimulant exposure.