| Research Abstract |
1) On the genetical analysis of anesthetic sensitivities : ED50s of Isoflurane (ISO) and Enflurane (ENF) were estimated as an index of loss of righting-reflex in ddN and C57BL mice, mutual hybrid mice and their backcross progenies. The results are as follows ;
(1) There is the difference of ENF and ISO sensitivities in ddN and C57BL mice. C57BL mice is more sensitive than ddN mice. This difference decreases into 1.18 - 1.26 times compared with the value of 1.38 times in 1990. A genetical factors related to anesthetic resistance in ddN mice may be being lost by means of the continuation of inbreeding.
(2) Multivariate regression analysis of parents' and F1 hybrids'data revealed that, while maternal factors and factors on autosomes were related to both anesthetics, the factors on the X chromosome were ENF specific. A wide variation i anesthetic requirements among backcross siblings progeny suggested multifacorial inheritance. The regression equations pbtained did not always predict anesthe
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tic requirement in backcross siblings progeny. These discrepancies may be due to the epistatic interaction of related genes. We conclude that multiple but different genetic factors are involved in determining ENF and ISO anesthetic requirements in ddN and C57BL mice.
2) Immunohistochemical analysis of brain neurotransmitters and receptors in ddN,C57BL and their hybrid (F1) mice.
(1) Serotonin : The density of serotonin-immuno reactive nerve fibers is ddN < C57BL in hippocampus CA1, CA2 and CA3, ddN > C57BL in dentate gyrus of hippocampus.
(2) Metencephalin : The immunoreactivity of mossy fiber of hippocampus is ddN > F1'> F1 > C57BL.
(3) Neuropeptide Y : The immunoreactive nerve cell is ddN < C57BL in parietotemmporal cortex and the immunoreactivity is 2 x ddN,F1, F1' < C57BL in suprachiasmatic nucleus, F1, F1' < ddN < C57BL in paraventricular nucleus, F1 < F1' and ddN < C57BL in spinal trigeminal nucleus, ddN < C57BL in cervical dorsal nucleus.
(4) Dopamine : The nigrostriatal dopaminergic pathway is more abundant in ddN than C57BL.The number of the dopaminergic neurons in the origin (substantia nigra) of ddN is about 30% larger than that of C57BL.The area of the terminal field (striatum) of ddN is larger than C57BL,and the staining intensity of tyrosine-hydroxylase immunoreactive structure, which can be interpreted as the density of the terminal, is higher in ddN than that of C57BL.
(5) Glutamate receptor : The localization of AMPA-selective gluamate receptor were examined using the antiserum made against the subunits : GluR1, GluR2/3, and GluR4. In the hippocampal CA1 and dentate gyrus, the distribution of GluR1 and GluR2/3 of C57BL are more dense than that of ddN.The staining intensity against the GluR2/3 antiserum in the parietal cerebral cortex is higher in C57BL than ddN.(The image analysis is in progress.) Less
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