Growth and neurotrophic factors regulating development and maintenance of sympathetic preganglionic neurons.

The functional anatomy of sympathetic preganglionic neurons is described at molecular, cellular, and system levels. Preganglionic sympathetic neurons located in the intermediolateral column of the spinal cord connect the central nervous system with peripheral sympathetic ganglia and chromaffin cells inside and outside the adrenal gland. Current knowledge is reviewed of the development of these neurons, which share their origin with progenitor cells, giving rise to somatic motoneurons in the ventral horn. Their connectivities, transmitters involved, and growth factor receptors are described. Finally, we review the distribution and functions of trophic molecules that may have relevance for development and maintenance of preganglionic sympathetic neurons.

The postnatal ontogeny of substance P-immunoreactive fibers in the sympathetic preganglionic nuclei of the rat.

The ontogeny of substance P (SP)-containing fibers and puncta is described in laminae VII and X of the rat thoracolumbar spinal cord from the day of birth until postnatal day (P) 60. As SP fibers and puncta innervate and demarcate the distribution of preganglionic sympathetic nuclei, strong temporal and weak rostrocaudal ontogenetic gradients exist. Additionally, a heterogeneous segmental SP ontogenetic pattern is observed in sympathetic nuclei. On the day of birth, SP fibers are present in an unorganized fashion in sympathetic nuclei with the exception of the nucleus intercalatus which is clearly outlined. From P0 to P4 SP fibers and puncta are established along a 'ladder-like' pattern and from P6 to P15 SP fibers and puncta steadily accumulate in sympathetic nuclei at all spinal levels. By P15 the nuclei intermediolateralis, pars principalis and funicularis, and the nucleus intercalatus are clearly outlined by SP immunoreactivity while the central autonomic region (lamina X) contains heterogeneous bands of SP immunoreactivity. From P20 to P30, SP fibers and puncta accumulate in each autonomic nucleus and longitudinal SP connections form between each adjacent nucleus intermediolateralis pars principalis. Along the spinal midline the nucleus intercalatus pars paraependymalis and the dorsal commissural nucleus emerge from the central autonomic region as separate SP-innervated nuclei. On P40 a period of reorganization takes place so that SP fibers within sympathetic nuclei become more diffuse and the nucleus intercalatus becomes more complex in appearance. The adult SP pattern is formed by P60 when the dorsal commissural nucleus dense core becomes the last autonomic region to be SP innervated. In addition, a transient population of immunohistochemically demonstrable cervical-thoracic laminae VII and X SP cell bodies are observed from P2 to P15.

Preganglionic neurons from the Edinger-Westphal nucleus: growth and histochemical characterization in cell culture.

The Edinger-Westphal (EW) nucleus, also known as the accessory oculomotor nucleus in the chick, provides the cholinergic preganglionic input to the parasympathetic ciliary ganglion. In addition to acetylcholine, many EW neurons have been shown to contain enkephalin-like and/or substance P-like immunoreactivity. Establishment of EW neurons in culture would make possible study of their interactions with ciliary ganglion neurons in vitro and in addition would provide a valuable system for studying cholinergic/peptidergic neurons of the vertebrate central nervous system. We describe here dissociated cell cultures established from midbrain tissue containing the EW nucleus. In these cultures, 86% of the cells with neuronal morphology were positive for intracellular acetylcholinesterase activity, 54% were positive for enkephalin-like immunoreactivity, and 4% were positive for substance P-like immunoreactivity. The proportions of neurons that scored as labeled were even higher if the number of positive cells was compared to the number of cells in sister cultures immunoreactive for the large neurofilament protein polypeptide. When the cultures were stained simultaneously for acetylcholinesterase activity and enkephalin-like immunoreactivity, 34% of the cells with neuronal morphology were positive for both. In cultures derived from adjacent tissue regions very few cells expressed both activities. These results suggest that the cells expressing both acetylcholinesterase activity and enkephalin-like immunoreactivity in culture are EW neurons. The putative EW neurons survive for weeks in vitro in the absence of their normal target, the ciliary ganglion.