Homozygous mice display a hyperactivity phenotype: Increased locomotion and rearing in Open Field test, and enhanced hyperactivity in response to ethanol administration. High frequency hearing loss in ABR assay.

This autosomal recessive mutation (tmgc20) linked to distal Chr 15, was detected in the progeny of C57BL/6JRn males given a single dose of 200 mg/kg ENU. The mutation is maintained on a segregating C3H:B6 background. Open Field: A cohort of mice, representing 4 generations, were tested. Mice displayed increased distance traveled in the 20-minute open field test (TOTAL_DISTANCE; 2.05 SD above the population mean). This pedigree also tended to rear more in the open field (REARING; 2.85 SD above the population mean). Ethanol: A cohort of mice, representing at least two generations were tested in an activity chamber 15 min. after an IP injection of ethanol. The 22TNJ pedigree exhibited high levels of locomotor activity in an activity chamber following a dose of 2.25 g/kg of ethanol. The mean for this activity measure (ACTI_TOT_DIST) was over 8.9 SD above the population mean. Similar results are found when the locomotor activity is examined in two 5-minute bins, although the behavior is more extreme at the second 5 minute bin then in the first. This behavior is not a result of abnormal ethanol metabolism as blood ethanol concentrations were normal in this pedigree of mice. Subsequent expanded testing examining baseline as well as ethanol-induced locomotor activity at 2 ethanol doses indicated that no differences were observed following saline injection, but the ethanol-induced locomotor activation was found only at both the 2.25 g/kg and the 1.5 g/kg dose of alcohol. Auditory We have tested a total of 11-12 mice in 4 generations of the 22TNJ pedigree. This pedigree shows significant high-frequency hearing loss at 16 and 32 kHz (see Mutant Detail PDF). When compared to all other TNJ/K pedigrees, ABR thresholds of 22TNJ are elevated significantly at 16 kHz (3.2 x SD) and 32 kHz (1.9 x SD) but insignificantly at click (0.9 x SD) and 8 kHz (0.9 x SD). High-frequency hearing loss is very common among human patients with progressive hearing impairment and age-related hearing loss. Thus this mutant could provide a model for such a common disorder.

Detailed data sheet

• Live mice (LM)