Role of interleukin-1β in the control of neuroepithelial proliferation and differentiation of the spinal cord during development

Interleukin-1β (IL-1β) is an important trophic factor in the nervous system (NS). IL-1β is ubiquitously expressed from very early stages during the development of the amphibian NS and its action has been demonstrated in vitro on survival, proliferation and differentiation in mammalian embryos. In this report, we show that IL-1β is immunocytochemically expressed in embryonic spinal cord from early stages, both in rat (embryonic day 12) and in chicken (stage 17-HH), in neuroepithelial cells and nerve fibres, dorsal root ganglia, anterior and posterior roots of the spinal nerves, and in the fibres of these nerves. Our in vivo experiments on chick embryos, with microbeads impregnated with IL-1β implanted laterally to the spinal cord at the level of the wing anlage, demonstrate that this cytokine produces a statistically significant increase in nuclear incorporation of BrdU at the dorsal level and a reduction of this at the ventral level, whereas local immunoblocking with anti-IL-1β antibodies causes a dorsal reduction of BrdU incorporation and alters ventral differentiation. These data demonstrate that IL-1β plays a part in controlling proliferation and early differentiation during the development of the spinal cord in chick embryos.