Behavioral consequences of methyllycaconitine in mice:: a model of α7 nicotinic acetylcholine receptor deficiency

Diminished expression of the alpha(7) nicotinic acetylcholine receptor occurs in selected brain regions of patients with schizophrenia, which may account for pathophysiological abnormalities and some of the deficits in attention and information processing. In view of this neurotransmitter receptor deficit, we wished to characterize the behavioral consequences associated with the administration of methyllycaconitine (MLA), a competitive alpha(7) nicotinic acetylcholine receptor antagonist, in mice. In this study, we injected groups of 12 outbred NIH Swiss male mice intraperitoneally with MLA (1.0, 3.2 and 10.0 mg/kg) and its saline vehicle. Thereafter, individual mice were observed over a one-hour interval and the intensity of a variety of behaviors were rated on a 4-point scale. The observed behaviors included: gnawing/chewing, rearing, grooming, sniffing, climbing, Straub tall, locomotion and ataxia. MLA produced statistically significant changes in the following observed behaviors: rearing, sniffing, climbing, and locomotion. A profile of the behavioral changes related to MLA administration in mice could lead to the development of a screening paradigm for alpha(7) nicotinic acetylcholine receptor agonist interventions. Ideally, an effective alpha(7) nicotinic acetylcholine receptor agonist intervention would target domains of psychopathology, especially cognitive symptoms that contribute to the profound functional disability that is often associated with schizophrenia. (C) 2004 Elsevier Inc. All rights reserved.