Vestibular Deprivation and the Development of Dendrite Bundles in the Rat

[摘要] Motoneuronal pools of muscles that subservepostural tasks contain dendrite bundles. Weinvestigated in the rat the development of thesebundles in the pools of the long back muscles andrelated this to postural development. Motoneuronsand their dendrites were retrogradelylabeled by injecting unconjugated cholera toxinsubunit B (CTB) into the muscles of 54 normalrats from birth until adulthood and into 18 ratsthat were vestibularly deprived from the 5thpostnatal day (P5). Dendrite bundles coursing ina transverse direction already occurred at P1.From P4, the first longitudinal bundles could beobserved, but the major spurt in developmentoccurred between P6 and P9, when conspicuousbundles developed coursing in rostro-caudal andtranverse directions. This is the age when ratsbecome able to stand freely and walk a few steps.Around P20, the dendrite bundles attained theiradult characteristics. Vestibular deprivation byplugging both semicircular horizontal canals didnot lead to a retarded development of dendritebundles nor to a changed morphology. Thisfinding is remarkable, as behavioral analysis showed a delay in postural development byabout 3 days. We hypothesize that dendritebundles in the pools of the long back musclesfunction to synchronize the motoneurons indifferent spinal cord segments.

[学科分类] 精神健康和精神病学