Effects of phencyclidine on aggressive behavior in squirrel monkeys

Area of Science:

• Neuroscience
• Behavioral Pharmacology

Background:

• Aggression is a complex behavior influenced by various neurochemical systems.
• Phencyclidine (PCP) is a dissociative anesthetic known to affect neurotransmitter systems implicated in aggression.

Purpose of the Study:

• To investigate the dose-dependent effects of phencyclidine (PCP) on both shock-induced and spontaneous aggression in squirrel monkeys.
• To characterize the behavioral responses, including attack and non-attack behaviors, following PCP administration.

Main Methods:

• Squirrel monkeys were subjected to two aggression paradigms: shock-induced aggression and spontaneous aggression.
• Phencyclidine (PCP) was administered subcutaneously at doses ranging from 0.01 to 1.0 mg/kg.
• Attack (hose-bite) and non-attack (lever press) responses were quantified in relation to shock delivery and spontaneous behavior.

Main Results:

• In shock-induced aggression, an initial increase in attack responses was observed with PCP, which diminished upon re-testing, with a subsequent increase in non-attack responses at higher doses.
• PCP administration led to increased non-attack responding at higher dosages in the spontaneous aggression paradigm.
• A dose-response relationship was established for PCP's effects on both aggression types.

Conclusions:

• Phencyclidine (PCP) exhibits complex and dose-dependent effects on aggression in squirrel monkeys, influencing both aggressive and non-aggressive behaviors.
• The findings suggest that PCP's impact on aggression is context-dependent and may involve modulation of specific behavioral outputs.
• Further research is warranted to elucidate the precise neurobiological mechanisms underlying PCP's differential effects on aggression.