Selective increase of offensive behavior in the rat following intrahypothalamic 5,7-DHT-induced serotonin depletion.
Cerebral serotonin (5-HT) depletions usually increase aggressive behaviors and more specifically facilitate elicitation of offensive behaviors. In order to localize the brain structures involved in this effect, 5,7-dihydroxytryptamine (5,7-DHT), a neurotoxin of 5-HT neurons, was injected into the ascending serotonergic pathway within the lateral hypothalamus, thus depleting 5-HT only in the forebrain structures. The effects of such treatment on offensive and defensive as well as social and non-social behaviors were studied in resident rats confronted with untreated intruders. Pretreatment with desipramine protected noradrenergic neurons. The content of 5-HT fell to 25% of controls, whereas noradrenaline was maintained at 90% in the forebrain anterior to the injection site. Ethological analysis of both resident's and intruder's behavior showed that offensive items were increased in 5,7-DHT-treated residents, whereas defensive items were increased in their non-treated partners; non-social activities were unchanged. Control of mouse-killing behavior during a 2-h test in the same animals showed a clear increase in elicitation of killing in 5,7-DHT-injected rats. These results confirm that the inhibitory control of serotonin is exerted specifically on offensive aggression. They suggest that forebrain structures are involved in this control.
Vergnes
M
M
Centre de Neurochimie C.N.R.S., INSERM, Strasbourg, France.
Depaulis
A
A
Boehrer
A
A
Kempf
E
E
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000374:Aggression / Q000502:physiology*; D000378:Agonistic Behavior / Q000502:physiology*; D000818:Animals; D001931:Brain Mapping; D004291:Dominance-Subordination; D007026:Hypothalamic Area, Lateral / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D011903:Raphe Nuclei / Q000502:physiology; D051381:Rats; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*
D011985:Receptors, Serotonin; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin