Developmental effect of dimethyl sulfoxide on hypothalamo-neurohypophysial neurons in vitro

Primary dissociated cultures were established from diencephalic tissue of 14-day-old fetal rats. Neurons exhibiting immunocytochemical staining for neurophysin appeared in these cultures after 6 days of cultivation. Addition of dimethyl sulfoxide (DMSO) to the culture medium resulted in a slight decrease in total neuronal cell mass as assessed by immunocytochemistry and radio-immunometric quantitation of neuron-specific enolase. In contrast, in DMSO-treated cultures the number of neurophysin-immunoreactive neurons was more than doubled as compared to control cultures. [3H]Thymidine labeling and autoradiography in conjunction with immunocytochemistry for neurophysin showed that this was not due to a mitogenic effect of DMSO on precursor cells. Time-course analysis of the action of DMSO revealed a 6-day time lag between the initiation of treatment and the appearance of increased numbers of neurophysin-immunoreactive cells. These findings suggest that DMSO, which has previously been reported to have a differentiation-inducing effect on malignant transformed cells, may also modulate cellular processes that control differentiation in specific types of neurons in primary culture.