Neuroreport. 2006 Apr 3;17(5):541-544.
An altered neonatal behavioral phenotype in Mecp2 mutant mice
Picker JD, Yang R, Ricceri L, Berger-Sweeney J.
Abstract
We examined somatic growth, somatosensory reflexes, and ultrasonic calls from postnatal day 3 to day 18 in Mecp2 mutant mice, a mouse model of Rett syndrome. Both Mecp2 null male and Mecp2 heterozygous female mice exhibited normal somatic growth, but transient delays in the development of some reflexes relative to sex-matched wild-type mice. Both Mecp2 null male and heterozygous female mice exhibited dramatic increases in ultrasonic vocalizations in response to social isolation; these differences were evident as early as postnatal day 5. These results suggest very early abnormalities in sensory reflex development and behavioral responsiveness in the Mecp2 mutants that may provide a target for early therapeutic intervention.
Lay Summary
In this study, the investigators performed a number of behavioral tests on MeCP2-deficient animals, performed in mice at ages much younger than usually examined. Interestingly, the earliest and most prominent altered behavior discovered by this group was increased ultrasound vocalizations. That is, the number of vocal calls made in response to separation from mother and littermates was much higher for MeCP2-deficient mice, and this difference was observed as early as 5-day-old mice. A key consequence of the report is that it provides further evidence for a change in the belief that these MeCP2-deficient mice do not show observable symptoms until 5-7 weeks of age. Rather, as clearly shown here, symptoms of altered neurological behavior can be observed in MeCP2-deficient mice as early as 5-days-old.