CNTF PROMOTES THE SURVIVAL OF NEONATAL RAT CORTICOSPINAL NEURONS INVITRO

CORTICOSPINAL neurons were identified in cell cultures of neonatal rat cortex by immunostaining of cholera toxin B subunit (CTB), retrograde ly transported from the cervical part of the spinal cord. The CTB-immu noreactive neurons were larger than the neurons in the overall (unstai ned) neuronal population and represented a small fraction of it (avera ge of 0.3%) after 6 hours in vitro. The number of both total and CTB-l abeled neurons declined progressively with time in culture. The neuron al death was, however, markedly faster in the CTB-labeled neuronal pop ulation than in the overall neuronal population. Ciliary neurotrophic factor (CNTF) promoted the survival of CTB-positive corticospinal neur ons in a dose-dependent manner; with CNTF, the death rate of the CTB-l abeled neurons became identical to that of the overall population.