All Phenotypes Chrna4<tm1Jpc> MGI Mouse

abnormal brain morphology ( J:54505 )

• nicotine and epibatidine binding sites are absent in most brain regions of mutant mice; reduced levels of nicotine binding are seen in the interpendicular nucleus (IP) while high levels of epibatidine persisted in the medial habenula (MH), superior colliculus (SC) and at low levels in the substantia nigra (SN)

abnormal nicotine-mediated receptor currents ( J:54505 )

• patch-clamp recordings indicate a loss of nicotine -elicited currents in serotonergic neurons in the raphe nucleus and thalamic neurons from mutant mice

• however, neurons in the superficial layers of the dorsal horn of the spinal cord continue to show a nicotine-elicited, dose-dependent augmentation of the frequency of post-synaptic currents

decreased chemically-elicited antinociception ( J:54505 )

• latency response to painful stimuli in the hot plate test and tail flick test does not differ significantly between mutant and control mice

• mutant mice do not show an antinociceptive response to the hot plate test at any dose of nicotine, whereas control mice show a dose-dependent antinociceptive response

• mutant mice treated with epibatidine do not exhibit an antinociceptive response in the hot plate test

• in contrast, nicotine causes a reduced but not absent dose-dependent analgesia in the tail flick test in mutant mice

• no significant differences in nociception are seen after morphine administration in mutant and control mice

immune system phenotype ( J:103908 )

N	• IgM levels of preimmune serum are little altered from control levels

increased IgG level ( J:103908 )

• increased IgG response to cytochrome c

decreased immunoglobulin level ( J:103908 )

• significantly reduced preimmune serum Ig levels

decreased IgG level ( J:103908 )

• preimmune actin and myosin binding antibody is significantly reduced