Knockout Corner: Neurobehavioural consequences of a serotonin 5-HT(2C) receptor gene mutation.
Studies employing nonselective serotonin 5-HT(2C) receptor agonists and antagonists have implicated this receptor subtype in many of the actions of serotonin. To further examine the function of this receptor, 5-HT(2C) receptor mutant mice were generated; studies of these animals reveal pleiotropic neurobehavioural effects of the mutation. Three examples are described: (1) Mutants exhibit chronically elevated food intake and the development of an obesity syndrome during the 'middle-age' portion of their lifespan. Their potential utility as a model of human obesity is further indicated by their enhanced sensitivity to high-fat feeding, leading to the development of type 2 diabetes. (2) 5-HT(2C) receptor mutants also display infrequent and sporadic spontaneous seizures. Further studies suggested the presence of globally enhanced neuronal network excitability in these mice. These findings raise the possibility that 5-HT(2C) receptors mediate a role for serotonin in the suppression of seizure activity. (3) Behavioural analysis of mutant mice revealed abnormal performance in a spatial learning task and altered exploratory behaviour, associated with perturbed long-term potentiation restricted to the dentate gyrus perforant path synapse. Taken together, the above findings implicate 5-HT(2C) receptors in the serotonergic regulation of feeding, neuronal network excitability, and hippocampal function.
Heisler
Lora K.
LK
Department of Psychiatry, University of California at San Francisco, San Francisco, CA 94143.
Tecott
Laurence H.
LH