Behavioural Brain Research 95 (1998) 227–232
Short communication
Effects of serotonergic drugs on lateralized aggression and aggressive
displays in Anolis carolinensis
A. Wallace Deckel *, Landon Fuqua
Uni6ersity of Connecticut Health Center, MC 2103, 263 Farmington A6enue, Farmington, CT 06030-2130, USA
Received 25 November 1997; received in revised form 23 February 1998; accepted 23 February 1998
Abstract
Previous work demonstrated that the brains of many reptiles, including the American chameleon Anolis carolinensis (A.
carolinensis), are functionally ‘split’. Because the left eye in this species projects predominantly to the right hemisphere, and vice
versa, inferences about lateralized brain functioning can be made in A. carolinensis by observation of eye use during behavioral
encounters. Using this model, past work suggested that territorial aggression in Anolis is under the preferential control of the right
hemisphere, and that acute stress or chronic alcohol exposure selectively reduces right hemisphere mediated territorial aggression.
In addition, drugs which increase serotonin (5-HT) in the synaptic cleft inhibit aggressive responding in anoles in both
hemispheres. The current experiment examined whether or not the administration of the serotonin agonists 8-hydroxy-2-(di-n-
propylamine) tetralin (8-OHDPAT), quipazine, or meta-chlorophenylbiguanide (mCPBG) alter territorial aggression in Anolis.
Nine adult socially isolated male A. carolinensis underwent a series of behavioral trials during which an antagonistic male was
introduced into the cage. Once stable responding was initiated, all subjects were injected in a semi-randomized crossover manner
with the following agents, (1) lactated Ringer’s, (2) the 5-HT2 agonist quipazine (1.5 mg/kg and 3.0 mg/kg), (3) the 5-HT1 agonist
8-OHDPAT (83 mg/kg), and (4) the 5-HT3 agonist mCPBG (3.0 mg/kg and 9 mg/kg). Twenty minutes post injections, the male
intruder was reintroduced into the subject’s cage. Several behaviors were recorded, including: (1) the time to th