Distribution of Met-enkephalyl-Arg-Gly-Leu in rat larynx: partial coexistence with vasoactive intestinal polypeptide, peptide histidine isoleucine and neuropeptide Y

Therapeutic concentrations of valproate but not amitriptyline increase neuropeptide Y (NPY) expression in the human SH-SY5Y neuroblastoma cell line

Neuropeptide Y (NPY) is a peptide found in the brain and autonomic nervous system, which is associated with anxiety, depression, epilepsy, learning and memory, sleep, obesity and circadian rhythms. NPY has recently gained much attention as an endogenous antiepileptic and antidepressant agent, as drugs with antiepileptic and/or mood-stabilizing properties may exert their action by increasing NPY concentrations, which in turn can reduce anxiety and depression levels, dampen seizures or increase seizure threshold. We have used human neuroblastoma SH-SY5Y cells to investigate the effect of valproate (VPA) and amitriptyline (AMI) on NPY expression at therapeutic plasma concentrations of 0.6mM and 630nM, respectively. In addition, 12-O-tetradecanoylphorbol-13-acetate (TPA) known to differentiate SH-SY5Y cells into a neuronal phenotype and to increase NPY expression through activation of protein kinase C (PKC) was applied as a positive control (16nM). Cell viability after drug treatment was tested with a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. NPY expression was measured using immunofluorescence and quantitative RT-PCR (qRT-PCR). Results from immunocytochemistry have shown NPY levels to be significantly increased following a 72h but not 24h VPA treatment. A further increase in expression was observed with simultaneous VPA and TPA treatment, suggesting that the two agents may increase NPY expression through different mechanisms. The increase in NPY mRNA by VPA and TPA was confirmed with qRT-PCR after 72h. In contrast, AMI had no effect on NPY expression in SH-SY5Y cells. Together, the data point to an elevation of human NPY mRNA and peptide levels by therapeutic concentrations of VPA following chronic treatment. Thus, upregulation of NPY may have an impact in anti-cancer treatment of neuroblastomas with VPA, and antagonizing hypothalamic NPY effects may help to ameliorate VPA-induced weight gain and obesity without interfering with the desired central effects of VPA.

Neurotransmitters and neuromodulators involved in laryngeal innervation

The distribution and role of neurotransmitters and neuromodulators in laryngeal innervation are reviewed, and our recent findings regarding the nitrergic innervation of the larynx are demonstrated for the better understanding of the complexity of the laryngeal innervation system. Noradrenergic innervation of the larynx was studied with fluorescence histochemistry and electron microscopy after application of 5-hydroxydopamine. These studies confirmed the existence of noradrenergic innervation for the submucosal glands and blood vessels, and the origin and course of noradrenergic nerve fibers contained in the laryngeal nerves and their destinations in the larynx. Cholinergic innervation of the larynx has not been clarified in detail. Many kinds of neuropeptides have been demonstrated to be involved in laryngeal innervation. Vasoactive intestinal polypeptide originating from intralaryngeal ganglionic neurons participates in laryngeal vasodilation and reduction of laryngeal seromucous secretion. Neuropeptide Y nerve fibers are few in the larynx, and most originate from the superior cervical ganglion. They are distributed around the large or medium-sized blood vessels, especially arteries. They are also associated with excretory structures. Substance P was the first neuropeptide found to be a sensory neurotransmitter in the laryngeal afferent system. It is also involved in regulation of laryngeal blood flow and secretion. Calcitonin gene-related peptide is associated with the sensory, autonomic, and motor innervation of the larynx. The majority of enkephalin nerve fibers are located close to excretory structures, although no information on the physiological significance of enkephalin is available. In addition to the above neuropeptides, the peptides histidine isoleucine, histidine methionine, and helospectin have been shown to exist in the larynx. The nitrergic innervation of the larynx has been recently studied with NADPH-diaphorase histochemistry and immunohistochemistry using antiserum against nitric oxide synthase. Nitric oxide originates from the neurons in the intralaryngeal ganglia and is believed to modulate blood flow and secretion of the larynx. It controls the laryngeal exocrine secretion in cooperation with intrinsic vasoactive intestinal polypeptide and/or extrinsic calcitonin gene-related peptide. Nitric oxide from the nodose ganglion may modulate nociception of the larynx. The existence of nitrergic neurons located in the intrinsic laryngeal muscles has been demonstrated. Many of them are bipolar or pseudounipolar, so they might be sensory in nature. The effect of injury of the recurrent laryngeal nerve on the induction of nitric oxide synthase in the laryngeal motoneurons is also discussed.

Coexpression of vasoactive intestinal peptide, calcitonin gene-related peptide and substance P immunoreactivity in parasympathetic neurons of the rhesus monkey lung

By the use of light microscopic immunohistochemistry, the present study investigates whether substance P (SP) and calcitonin gene-related peptide (CGRP), which are well documented neurotransmitter candidates in primary sensory fibers, are also expressed in parasympathetic neurons of the rhesus monkey lung. A combination of double fluorescence immunohistochemistry and staining of adjacent sections revealed triple coexistence of SP, CGRP and the cholinergic co-transmitter vasoactive intestinal peptide (VIP) in a large number of neuronal cell bodies in intrinsic peribronchial ganglia. In addition, there was co-localization of SP and CGRP in choline acetyl-transferase (ChAT)-positive neurons. These data suggest that SP and CGRP, in addition to their sensory role, are cholinergic cotransmitter candidates in the postganglionic parasympathetic innervation of primate lung. Co-release and co-function of SP and CGRP with VIP and acetylcholine may be important in the regulation of pulmonary physiology and in pulmonary pathophysiology.

Irradiation influences the expression of substance P and enkephalin in the rat larynx

The effects of radiotherapy on neuropeptide expression in the rat larynx were studied. Irradiation was given for five days, 6 or 8 Gray daily. Ten days after the end of irradiation, the larynx, the laryngeal nerves and different ganglia related to the larynx were dissected out from irradiated and control animals and processed for neuropeptide immunohistochemistry. There was an increased immunolabelling for two of the neuropeptides tested, substance P and enkephalin, in the innervation of the subglottic glands and in the acetylcholinesterase-positive ganglionic cells of the local ganglia. These cells were interpreted as representing postganglionic parasympathetic ganglionic cells. The changes seen in the subglottic glands were interpreted as most likely being related to the changing pattern of staining seen in the local ganglia. No changes in substance P- and enkephalin expression were observed in other laryngeal structures, the nodose ganglia, superior cervical ganglia or laryngeal nerve paraganglia. Thus, in certain respects neuropeptide expression in the larynx is modulated by radiotherapy. Since neuropeptides have both neurotransmitter and/or neuromodulator effects in airway tissue and since they show effects as growth factors, the occurrence of this plasticity in neuropeptide expression should be taken into consideration in future studies examining the effects of irradiation on normal/diseased airway tissues.

Precise localization of VIP-, NPY-, and TH-immunoreactivities of cat laryngeal glands

The precise distribution of vasoactive intestinal polypeptide (VIP)-, neuropeptide Y (NPY)-, and tyrosine hydroxylase (TH)-immunoreactive (ir) fibers in the cat's laryngeal glands was examined by immunoelectronmicroscopy. A relatively dense population of VIP-ir fibers was recognized close to the basal lamina of the glandular and myoepithelial cells. Some VIP-ir fibers contacted with the basal lamina and some of them pierced it and ran intercellularly in the adjoining glandular cells without making synaptic contacts with them. NPY- and TH-ir fibers were located in the vicinity of the basal lamina, but they were less abundant than VIP-ir fibers at this region. They never terminated or penetrated the basal lamina. Pattern of distribution of TH-ir fibers was similar to that of NPY-ir fibers. The estimated ratio of VIP-, TH-, and NPY-ir fibers was 20:4:1 from the density of fibers in the laryngeal glands. This value was equal between serous and mucous glandular cells, so both types of glandular cells may receive the same pattern of autonomic innervation.

Distribution and relative proportions of neuropeptide Y- and proenkephalin-containing noradrenergic neurones in rat superior cervical ganglion: separate projections to submaxillary lymph nodes

The distribution and relative proportions of neuropeptide Y (NPY)- and [Met]enkephalyl-Arg-Gly-Leu (ME-RGL)-containing sympathetic neurones in the rat superior cervical ganglion (SCG) and their projections to submaxillary lymph nodes (SLN) were determined by retrograde tracing and immunocytochemistry. Three subpopulations of neurones were detected in the SCG: 64% contained NPY, 30% contained ME-RGL, and 6% were immunonegative for both. Immunoreactive neurones were also present inside the external carotid nerve of the SCG. An injection of Fluoro-Gold (FG) into the left SLN retrogradely labeled a few neurones in the ipsilateral SCG. FG-labeled neurones contained tyrosine hydroxylase (TH) and were either positive for ME-RGL or for NPY. FG-labeled neurones immunostained for ME-RGL out-numbered by 4:1 FG-labeled neurones immunopositive for NPY. It is suggested that the sympathetic/peptidergic innervation to SLN may have distinct vasoregulatory and immunomodulatory functions.

Distribution of SP- and CGRP-immunoreactivity in the cat's larynx

The distribution of substance P (SP) and calcitonin gene-related peptide (CGRP) immunoreactive (ir) fibres in the cat's larynx was investigated utilizing immunohistochemistry. Many SP- and CGRP-ir fibres with varicosities were found within and below the epithelium and along the basement membrane of the mucosa of all different regions except in the membranous portion of the vocal fold. In the subepithelium, some SP- and CGRP-ir nerve bundles and nerve fibres were recognized around the vessels and glands. In the mucosa, the pattern of distribution and the density of SR-ir fibres were similar to those of CGRP-ir fibres. These reactive fibres were denser in the supraglottic region than in the subglottic region. In the taste bud-like structures, only SP-ir fibres appeared, whereas in the motor endplates, CGRP-reaction was found exclusively. The present findings suggest that the regional distribution of SP- and CGRP-immunoreactivity might be related with sensory and autonomic innervation in the larynx.

Molecular anatomy of the neuro-immune connection

Light microscopic immunohistochemistry was employed to elucidate and compare the presence, distribution, and coexistence of various peptides, neuroendocrine markers and enzymes of the catecholamine pathway in nerves supplying lymphoid tissues in a variety of mammalian species. All lymphoid organs and tissues receive innervation by fibers containing dopamine-beta-hydroxylase and/or tyrosine hydroxylase, neural markers like protein gene product 9.5, synaptophysin and neurofilament and a varied spectrum of peptides. The prominent peptides were tachykinins (substance P, neurokinin A), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), and vasoactive intestinal polypeptide/peptide histidine isoleucine (VIP/PHI). Opioid innervation was variable. Double immunofluorescence revealed coexistence of tachykinins and CGRP and of tyrosine hydroxylase and NPY. A minor proportion of fibers showed coexistence of NPY and tachykinins and of VIP/PHI and tachykinins. The possible importance of the complex peptidergic innervation of lymphoid tissues in inflammation, allergy, inflammatory pain and psycho-neuro-immuno-endocrine network function is discussed. A special immunomodulatory role of the sensory neurons is suggested.