Role of brain dopaminergic mechanisms in rodent aggressive behavior: Influence of (�)N-n-propyl-norapomorphine on three experimental models

Abstract

(+/-)N-n-Propyl-norapomorphine (NPA), a potent agonist of brain dopamine receptors, influences aggressive behavior, but the type of influence depends on the experimental conditions. In rats, NPA increases aggression elicited by electrical foot shock, but decreases predatory aggression against turtles as well as isolation-induced aggression in male mice. NPA proves more potent than apomorphine in both the foot shock and predatory test. A per se ineffective dose of haloperidol (0.05 mg/kg-1 IP) antagonizes NPA in the rat foot shock test as well as in the isolated male mouse test. The relevance of stereotyped movements for NPA influence on aggressive behavior is briefly discussed.

Predatory aggression, but not maternal or intermale aggression, is associated with high voluntary wheel-running behavior in mice

“…Recent work suggests that dopamine D1 receptor function is reduced in the S lines Rhodes et al, 2001) and other studies have implicated dopamine in predatory aggression in rodents and carnivores (ferrets) (Baggio and Ferrari, 1980;Jimerson and Reis, 1973;Schmidt, 1979;Schmidt, 1983;Siegel et al, 1999). Dopamine facilitates predatory aggression, possibly via D2 receptors, in some studies (Shaikh et al, 1986;Siegel et al, 1999), yet dopamine receptor antagonists also facilitate this behavior in other studies (Baggio and Ferrari, 1980;Schmidt, 1979;Schmidt, 1983). These varying results suggest it will be critical to understand exactly where in the brain and at what levels dopamine is released (or inhibited from release) to determine how dopamine is involved in predatory aggression.…”

“…However, the exact mechanisms of differences in dopamine signaling between S and C mice is still not known. Various studies have implicated dopamine in predatory aggression in rodents and carnivores (ferrets) (Baggio and Ferrari, 1980;Jimerson and Reis, 1973;Schmidt, 1979;Schmidt, 1983;Siegel et al, 1999). Given likely differences in dopamine signaling and recent work indicating higher levels of activation of the brain reward circuitry in S relative to C mice , we hypothesized that there would be significant differences in predatory aggression between S and C mice.…”

The rewarding effect of aggression is reduced by nucleus accumbens dopamine receptor antagonism in mice

“…However, what role each DA receptor subtype serves in contingent aggression is yet to be determined. Experiments administering apomorphine (a semiselective D2-like DA receptor agonist) and N-propylnorapomorphine (a potent D2-like DA receptor agonist) have shown a facilitative agonistic effect under predatory, foot shock, and isolation-induced aggression paradigms (Baggio and Ferrari 1980;Miczek et al 2002;Siegel et al 1999). Complementing the findings of these experiments are studies using haloperidol and raclopride (D2-like DA receptor antagonists), which decreased aggression in rodents and humans, although the findings are problematic due to undesired motor side effects Siegel et al 1999).…”

γAminobutyrate B Receptors in Central Amygdaloid and Medial Amygdaloid Nuclei of Amygdala Modulate Aggression in Male Rats

“…Offensive aggression was induced by 0.2 mA for one sec electrical current stimulation applied every 3 sec for 5 min, i.e., each animal received 100 electrical shocks every session (Baggio and Ferrari, 1980). After electrical shock, another rat was placed in the electroshock chamber and the animals were monitored for the signs of various offensive aggression behaviors and these were appropriately recorded by camera for 20 min.…”