Presence Of Cholinergic Fibers Research Articles

Immunohistochemical investigations of the autonomous innervation of the cervine testis

The innervation of the cervine testis was studied in 6 roe deers, 7 red deers and 14 fallow deers. The results for the three species are rather similar. With anti-sera to neurofilament (NF) and neuron specific enolase (NSE), all small and large nerve fascicles can be demonstrated, but single fibers are incompletely stained. Immunoreactions against protein gene product-9.5 (PGP-9.5) and GAP-43 (growth-associated protein-43) are better suited to depict the complete innervation pattern. Bundles of the superior spermatic and inferior spermatic nerves reach the testis via three access routes as funicular, mesorchial and caudal nerve contributions. We found no morphological evidence that the nerves in the cervine testis are directly involved in regulating Leydig cell function or seminiferous tubular motility. The majority of the testicular nerves are associated with the testicular arteries, but the musculature in the walls of the venous plexus pampiniformis is also innervated. All vascular nerve fibers represent postjunctional sympathetic axons displaying a strong dopamine-beta-hydroxylase (DBH) activity, mostly co-expressed with neuropeptide Y (NPY). The presence of cholinergic fibers in the testis of the deer is only sporadic and probably of no functional importance. In all three species of deer, a small quantity of myelinated nerve fibers is encountered in spermatic cord and tunica albuginea and regarded as afferent. The viscerosensory quality in the testicular intrinsic innervation is very likely mediated by the CGRP (calcitonin gene-related peptide)-positive fibers that run independently from the testicular vessels and end in the connective tissue of spermatic cord and tunica albuginea. The testis of the red deer contains significantly more VIP (vasoactive intestinal polypeptide)-positive axons than that of roe and fallow deer. The nerve density in the interior of the testicular lobules shows no regional differences, but there are age- and season-related changes that correlate with the developmental and functional state of the seminiferous tubules. Small testes with solid and narrow tubules, as seen in the prepuberal phase and during seasonal reproductive quiescence, are better innervated than large testes with expanded and spermatogenetically active seminiferous tubules.

Presence of cholinergic neurons in the vagal afferent system: Biochemical and immunohistochemical approaches

The presence of cholinergic fibers in the afferent vagal system of various species was shown using biochemical and immunohistochemical methods. Biochemical activity of choline acetyl transferase, the synthesizing enzyme for acetylcholine, was detected in the nodose ganglion of cat, rabbit, dog and sheep. Immunohistochemistry, using a monoclonal antibody raised against choline acetyl transferase, revealed labelled cell bodies in the nodose ganglion of the rabbit. Acetylcholine endogenous content, measured in nodose ganglia devoid of efferent fibers, was twice as high in the right ganglion as compared to the left. Enzyme transport and choline acetyl transferase activity analysis were each determined on separate peripheral vagus nerves. These results are discussed in terms of functional properties of the vagal afferent neurons, including the modulation of vagal afferent messages at the level of the nodose ganglion and the eventual control of peripheral intrinsic neurons by sensory vagal terminals.

Decrease in choline acetyltransferase activity in the red nucleus of the cat after cerebellar lesion

The use of a microdissection technique and of a very sensitive radioisotopic assay for choline acetyltransferase, the enzyme that synthesizes acetylcholine, showed that the distribution of this enzyme in the feline red nucleus is uneven. Thus, the enzyme content progressively increased in the caudo-rostral direction, the level at the rostral aspect being about twice that at the caudal. Choline acetyltransferase activity in the cat red nucleus was examined after chronic lesions of the cerebellum. Lesions in the area of the dentate and interpositus nuclei were followed by a decrease in enzyme activity in the contralateral red nucleus, whereas no change was seen on the ipsilateral side. Since this enzyme is a very specific marker for cholinergic neurons, the decrease in enzyme activity caused by the lesions suggests the existence of a cholinergic cerebellorubral pathway. This is supported by the finding that the topographical effects on choline acetyltransferase activity in the red nucleus produced by selective lesions of either the dentate or the interpositus nucleus reflected the arrangement of the cerebellorubral pathways. Choline acetyltransferase activity also decreased in the nucleus ventralis lateralis and the nucleus ventralis anterior of the thalamus contralateral to the lesions. Since cerebello-rubral fibres are thought to be collaterals of cerebello-thalamic axons, at least in the case of these originating in the interpositus nucleus, this would indicate the presence of cholinergic fibres in the brachium conjunctivum (or superior cerebellar peduncle). The results are not in complete agreement with some of the previously reported pharmacological studies; this is discussed.