HIPPOCALCIN EXPRESSION IN THE BRAIN OF THE SNELL DWARF MUTANT MOUSE

To determine factors contributing;to the expression of the brain-deriv ed protein, hippocalcin, we mapped its distribution in the brain of Sn ell pituitary dwarf mutant mice (dw) by immunohistochemical and immuno blot methods. Our findings are as follows. (1) In the hippocampus, hip pocalcin immunoreactivity was found in the cell body and dendrites of pyramidal neurons of the normal controls and dw mice, although the int ensity of immunoreactivity in the dw mice was lower. (2) In the cerebe llum, hippocalcin immunoreactivity was strongly expressed in the Purki nje cell body of both the control and dw mice. However, the Purkinje c ell dendrites were found to be more intensely stained in the dw mice t han in the normal controls. (3) In the dw cerebral cortex, the pyramid al neurons of layers II to VI strongly expressed hippocalcin, whereas its expression in the controls was weak. (4) The amount of hippocalcin in the dw hippocampus was less than in the normal controls, whereas t he amount in the dw cerebral cortex and cerebellum was greater. These results indicate that the developmental expression of hippocalcin in t he dw brain is affected by the retarded maturation of the neuronal net work due to the deficient hormonal state (the lack of growth and thyro id hormones).