Time-dependent regulation of perineuronal nets in the cerebellar cortex during abstinence of cocaine-self administration.

Rationale: The probability of structural remodeling in brain circuits may be modulated by molecules of perineuronal nets (PNNs) that restrict neuronal plasticity to stabilize circuits. Animal research demonstrates that addictive drugs can remodel PNNs in different brain regions, including the cerebellum.

Objective: This study aimed to investigate the effects of short versus extended access to cocaine self-administration on PNN expression around Golgi interneurons in the cerebellar cortex after different periods of abstinence.

Methods: After 1 week of training (2 h/day), Sprague-Dawley rats self-administered cocaine daily for 20 days under short (ShA) or extended (LgA) access. PNN expression in the cerebellum was assessed after 1 day, 7 days, and 28 days of forced abstinence. PNNs were immunolabeled using Wisteria floribunda agglutinin (WFA) and captured by confocal microscopy.

Results: WFA intensity increased in PNN-bearing Golgi neurons over the abstinence period and a higher proportion of more intense PNNs were formed throughout the first month of abstinence. After the first 24 h of cocaine abstinence, however, we found a reduction in WFA intensity in the cerebellar cortex of rats with ShA to cocaine as compared to naïve animals. When comparing with naïve rats, LgA rats showed consistent PNN upregulation at 28 days of cocaine abstinence.

Conclusions: Our results suggest that cocaine self-administration produces modifications in PNN that enhance conditions for synaptic plasticity in the cerebellar cortex. These modifications are revealed shortly after the cessation of drug intake but PNNs become more intense during protracted abstinence in the LgA group, pointing to the stabilization of drug-induced synaptic changes. These findings indicate that extended access to cocaine self-administration dynamically regulates conditions for plasticity in the cerebellum during abstinence.