World Journal of
Pharmaceutical and Life Sciences

CAUDATE NUCLEUS NEURONAL RECORDINGS IN FREELY BEHAVING SD MALE RATS AGE DEFERENT VARIATION IN RESPONSE TO DOPAMINE AGONIST METHYLPHENIDATE (RITALIN): INTEGRATED BEHAVIORAL

Dafny N.*, Claussen C., Frazier E. and Lin Y.

ABSTRACT

The study explores age-related differences in response to acute and chronic dopamine (DA) agonist methylphenidate (MPD) doses (0.6, 2.5, and 10.0 mg/kg) in freely behaving young and adult male rats. Simultaneous recordings of caudate nucleus (CN) neuronal activity and locomotor behavior aim to discern age-related variations in MPD response and potential correlations between behavioral expression and CN neuronal activity. The investigation reveals that chronic MPD administration at 0.6, 2.5, and 10.0mg/kg doses induces behavioral and electrophysiological tolerance in some animals and sensitization in others, compared to initial MPD dosages. Notably, significant differences exist in CN neuronal responses and behavioral expressions between the two age groups, highlighting age-dependent variations in responses to the DA agonist MPD exposure. Correlations were observed between the behavioral responses to varying MPD doses and the direction of CN neuronal response (excitation or attenuation) to the drug. These findings underscore the importance of evaluating drug effects on specific brain regions based on the animals' behavioral responses, particularly regarding chronic effects like sensitization and tolerance. Moreover, significant differences in both behavioral and electrophysiological responses were noted between young and adult rats in response to MPD. These distinctions underscore the necessity for more in-depth investigations to elucidate the impact of MPD on the developing brain and its potential long-term effects on neuronal function. The implication of this study is the critical need to assess neuronal responses within specific brain regions based on the behavioral responses exhibited by animals, particularly in the context of chronic MPD effects such as sensitization and tolerance. Understanding age-dependent variations is pivotal for comprehending the nuanced impact of MPD on neuronal function and behaviors.

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