Phenotypes associated with this allele

• Allele Symbol: Chrna7^tm2Bay
• Allele Name: targeted mutation 2, Baylor College of Medicine
• Allele ID: MGI:2155604
• Summary: 1 genotype

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Chrna7^tm2Bay/Chrna7^tm2Bay	involves: 129S7/SvEvBrd * C57BL/6J	MGI:3846063

Genotype
MGI:3846063

hm1

• Allelic Composition: Chrna7^tm2Bay/Chrna7^tm2Bay
• Genetic Background: involves: 129S7/SvEvBrd * C57BL/6J

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

mortality/aging

neonatal lethality, complete penetrance ( J:61536 )

• homozygous mice always die within 2-24 hours of birth

behavior/neurological

abnormal suckling behavior ( J:61536 )

• pups do not suckle

tremors ( J:61536 )

• neonatal pups exhibit slight tremors in their extremities

decreased locomotor activity ( J:61536 )

• neonatal pups are relatively inactive

nervous system

increased neuron apoptosis ( J:61536 )

• homozygous neonatal mice exhibit an overall higher number of TUNEL stained cells in the developing brain than control littermates, predominantly in regions that normally express alpha-7 nAChRs

• increased TUNEL labeling is also visible in the ventral posterior medial nucleus and in the habenula

• interestingly, the hippocampus and olfactory bulb of homozygous mice, which exhibit high levels of a7 mRNA and ¹²⁵I-alpha-BTX binding site expression in normal animals, showed lower levels of TUNEL cell labeling relative to the somatosensory cortex, yet higher than in littermate controls

abnormal brain morphology ( J:61536 )

• a significant reduction in ¹²⁵I-alpha-BTX binding was observed throughout the brain in neonatal mice compared to controls; levels are reduced by as much as 65-75% in the somatosensory cortex, hippocampus, and olfactory bulb of the brains of homozygous neonatal mice

• gross morphology of the brain is similar to controls

abnormal somatosensory cortex morphology ( J:61536 )

• at P0, in the somatosensory cortex of homozygous mice, apoptotic cell death was observed throughout layers 6 and 5 and was rarely seen in the cortical plate

• in addition, no clear differentiation between layers 6 and 5 is seen; instead, there were small densely packed cells throughout this region

abnormal nicotine-mediated receptor currents ( J:61536 )

• in homozygous mice, the currents evoked by 500 mM nicotine were inhibited by 5 nM MLA but showed little desensitization; the current amplitude was relatively small compared with controls

cellular

increased neuron apoptosis ( J:61536 )

• homozygous neonatal mice exhibit an overall higher number of TUNEL stained cells in the developing brain than control littermates, predominantly in regions that normally express alpha-7 nAChRs

• increased TUNEL labeling is also visible in the ventral posterior medial nucleus and in the habenula

• interestingly, the hippocampus and olfactory bulb of homozygous mice, which exhibit high levels of a7 mRNA and ¹²⁵I-alpha-BTX binding site expression in normal animals, showed lower levels of TUNEL cell labeling relative to the somatosensory cortex, yet higher than in littermate controls