The effect of 5-HT(2a/2c) receptor agonist microinjected into central amygdaloid nucleus and median preoptic area on maternal aggressive behavior in rats.
OBJECTIVE
Much evidence supports the hypothesis that 5-hydroxytryptamine (5-HT) activation is related to the inhibition of aggression. We examined potentially pro- and anti-aggressive effects of the 5-HT(2A/2C) receptor agonist on specific brain sites.


METHODS
Female Wistar rats on the 7th day postpartum were microinjected with the selective 5-HT(2A/2C) receptor agonist, alpha-methyl-5-hydroxytryptamine maleate (0.2 to 1.0 microg/0.2 microl) into the central amygdaloid nucleus and median preoptic nucleus. For each brain area studied, the frequency of the behaviors: locomotion, social investigation, lateral threat, attacks (frontal and lateral), and biting the intruder were compared among the various treatments by an Analysis of Variance, followed when appropriate, by Tukey's test.


RESULTS
Microinjection of the selective 5-HT(2A/2C) receptor agonist, a-methyl-5-hydroxytryptamine maleate into central amygdaloid nucleus increased maternal aggression in the absence of concurrent changes in non-aggressive behavior. By contrast, microinjection of the selective 5-HT(2A/2C) receptor agonist at several dilutions into the median preoptic nucleus did not alter aggressive behavior.


CONCLUSIONS
The current and earlier data with pro- and anti-aggressive effects of the 5-HT(2a/2c) receptor agonist, when microinjected into the median preoptic nucleus relative to the central amygdaloid nucleus, medial septum and periaqueductal grey area in female rats point to functionally separate serotonin receptor populations in the amygdaloid-septal-hypothalamic and periaqueductal gray matter areas controlling aggressive behavior. It is possible that amygdaloid 5-HT(2a/2c) receptors may increase aggressive behavior in lactating females as a result of changes in fear.
de Almeida
Rosa Maria Martins
RM
Laboratory of Neurosciences, Health Sciences, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, Brazil. rmalmeida@unisinos.br
Giovenardi
Marcia
M
da Silva
Simone Perroni
SP
de Oliveira
Verônica Paz
VP
Stein
Dirson João
DJ
D000374:Aggression / Q000187:drug effects*; D000679:Amygdala / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D008425:Maternal Behavior / Q000187:drug effects*; D008845:Microinjections; D011301:Preoptic Area / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D058826:Serotonin 5-HT2 Receptor Agonists; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage* / Q000494:pharmacology
D058826:Serotonin 5-HT2 Receptor Agonists; D017366:Serotonin Receptor Agonists; C042390:alpha-methylserotonin; D012701:Serotonin