Microcephalic cerebrum with hypomyelination in the pygmy mouse (pg).
To determine whether somatomedin has a direct action on cerebral development instead of an indirect action of a growth hormone, we examined the central nervous system of the pygmy mouse (pg), a mutant with normal somatomedin activity. Our findings are: (A) the weights of the pg/pg cerebrum and cerebellum weighted were significantly less than those of the normal controls (pg/+), 14 and 15% less, respectively; (B) the total DNA content was reduced by 17% in the cerebrum and cerebellum of the pg/pg mouse; (C) the total RNA content was reduced in the cerebrum and cerebellum, proportional to the reduction in DNA; (D) CNPase activity was reduced selectively in the cerebrum of the pg/pg mouse by 25%; and (E) the pg/pg mice exhibited a strikingly reduced level of activity with an indistinct diurnal periodicity. Therefore, the present findings suggest that the action of somatomedin on the proliferation and maturation of glial cells might be a necessary precondition to myelin formation.
Sugisaki
T
T
Department of Physiology, Toho University School of Medicine, Tokyo, Japan.
Beamer
W G
WG
Noguchi
T
T
D000818:Animals; D001835:Body Weight; D001921:Brain / Q000201:enzymology / Q000473:pathology*; D001923:Brain Chemistry / Q000502:physiology; D002147:Calmodulin / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D003711:Demyelinating Diseases / Q000235:genetics / Q000473:pathology* / Q000523:psychology; D005260:Female; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008831:Microcephaly / Q000235:genetics / Q000473:pathology*; D009043:Motor Activity; D009186:Myelin Sheath / Q000201:enzymology; D009929:Organ Size / Q000502:physiology; D012313:RNA / Q000378:metabolism
D002147:Calmodulin; D012313:RNA; D004247:DNA