Immunohistochemical characterization of neurons in the porcine ciliary ganglion.

The present study was aimed at disclosing the chemical coding of nerve structures in the porcine ciliary ganglion (CG) using immunohistochemical methods. The substances under investigation included markers of "classical" neurotransmitters, choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DbetaH) as well as neuropeptides, somatostatin (SOM), galanin (GAL), substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP) and neuropeptide Y (NPY). Immunoreactivity to ChAT and VAChT was found virtually in all the neuronal somata and in numerous intraganglionic, varicose nerve fibres which often formed basket-like formations around the nerve cell bodies. Many CG neurons contained immunoreactivity for SOM (46%) or GAL (29%). Interestingly, a small number (approx. 1%) of the cholinergic somata stained for TH but not for DbetaH; nevertheless, some extra- and intraganglionic nerve fibres displayed immunoreactivity for DbetaH or TH. The CG perikarya stained neither for vasoactive intestinal polypeptide (VIP) nor for neuropeptide Y (NPY), but some NPY- or VIP-positive nerve terminals were observed within nerve bundles distributed outside the ganglion. SP- and CGRP-immunoreactivity was found in some intraganglionic nerve fibres only. The present study revealed that the porcine CG consists of cholinergic neurons many of which contain SOM and GAL. Thus, it can be assumed that in the pig, these neuropeptides are involved, complementary to acetylocholine, in the parasympathetic postganglionic nerve pathway to structures of the eye including the ciliary and iris sphincter muscles.

Central nervous system innervation of the penis as revealed by the transneuronal transport of pseudorabies virus.

Transneuronal tracing techniques were used in order to identify putative spinal interneurons and brainstem sites involved in the control of penile function. Pseudorabies virus was injected into the corpus cavernosus tissue of the penis in rats. After a four day survival period, rats were perfused with fixative and virus-labelled neurons were identified by immunohistochemistry. Postganglionic neurons were retrogradely labelled in the major pelvic ganglia. In the spinal cord, sympathetic and parasympathetic preganglionic neurons were labelled transneuronally. Presumptive interneurons were also labelled in the lower thoracic and lumbosacral spinal cord in locations consistent with what is currently known about such interneurons. In the brainstem, transneuronally labelled neurons were found in the medulla, pons and hypothalamus. Regions consistently labelled included the nucleus paragigantocellularis, parapyramidal reticular formation of the medulla, raphe pallidus, raphe magnus, A5 noradrenergic cell group, Barrington's nucleus and the paraventricular nucleus of the hypothalamus. This study confirmed previous studies from our lab and others concerning the preganglionic and postganglionic neurons innervating the penis. The number, morphology and location of these neurons were consistent with labelling seen following injection of conventional tracers into the penis. The brainstem nuclei labelled in this study were also consistent with what is currently known about the brainstem control of penile function. The labelling appeared to be highly specific, in that descending systems involved in other functions were not labelled. These results provide further evidence that the pseudorabies virus transneuronal tracing technique is a valuable method for identifying neural circuits mediating specific functions.

Control of Na+, K+-pump activity in dorsal root ganglionic neurons by different neuronotrophic agents.

Na+, K+-pump activity is indispensable for neuronal survival in vitro and a specific role in its regulation has been demonstrated for the NGF action on its target neurons. We have extended these earlier studies to include two other neuronotrophic agents: the chick eye-derived ciliary neuronotrophic factor (CNTF); and 12-O-tetradecanoyl-phorbol-13-acetate (TPA). CNTF and TPA individually supported the survival of an identical (and maximal) number of embryonic day 10 (E10) dorsal root ganglion (DRG) neurons as did NGF. E10 DRG neurons, seeded as monolayer cultures with 86Rb+ (as K+ tracer) but no trophic supplement in their medium, received NGF, CNTF, TPA, or no agent at 2, 4 or 6 h after seeding. The cultures were analyzed at 6 and 24 h for Na+, K+-pump performance and at 24 h for neuronal survival. Neurons receiving no agent lost their pump activity over the first 6 h and died over the 10-24 h incubation period. Both pump performance and survival were fully supported by any one of the 3 agents when provided at seeding time. Delayed presentation of NGF also led to full restoration of pump activity and survival support, as expected. In contrast, CNTF and TPA failed to correct the increasing pump deficits incurred with increasing times of trophic deprivation, and neuronal survival was proportionally reduced. Delayed addition of CNTF and TPA did, however, prevent further losses of both pump and viability. Close similarities were observed between pump failure and cell losses, demonstrating a linear correlation between pump performance and neuronal survival.(ABSTRACT TRUNCATED AT 250 WORDS)