Vagal Control of Satiety and Hormonal Regulation of Appetite

The paradigm for the control of feeding behavior has changed significantly. In this review, we present evidence that the separation of function in which cholecystokinin (CCK) controls short-term food intake and leptin regulate long-term eating behavior and body weight become less clear. In addition to the hypothalamus, the vagus nerve is critically involved in the control of feeding by transmitting signals arising from the upper gut to the nucleus of the solitary tract. Among the peripheral mediators, CCK is the key peptide involved in generating the satiety signal via the vagus. Leptin receptors have also been identified in the vagus nerve. Studies in the rodents clearly indicate that leptin and CCK interact synergistically to induce short-term inhibition of food intake and long-term reduction of body weight. The synergistic interaction between vagal CCK-A receptor and leptin is mediated by the phosphorylation of signal transducer and activator of transcription3 (STAT3), which in turn, activates closure of K+ channels, leading to membrane depolarization and neuronal firing. This involves the interaction between CCK/SRC/phosphoinositide 3-kinase cascades and leptin/Janus kinase-2/phosphoinositide 3-kinase/STAT3 signaling pathways. It is conceivable that malfunctioning of these signaling molecules may result in eating disorders.

Expression of growth hormone secretagogue receptor type 1a in visceral vagal and spinal afferent pathways / 生理学报

In this study, the expressions of growth hormone secretagogue receptor type 1a (GHS-R1a) in the rat dorsal root ganglion (DRG) and nodose ganglion (NG) were investigated by using immunohistochemistry and in situ hybridization. The results clearly showed the presence of GHS-R1a mRNA and GHS-R1a-positive neurons in the rat DRG and NG. GHS-R1a was also co-localized with calcitonin gene-related peptide (CGRP) in some DRG and NG neurons, indicating the existence of subpopulations of the visceral afferents. The extrinsic primary afferent visceroceptive DRG and NG neurons from the stomach were identified by retrograde tracing fluorogold and stained for GHS-R1a and CGRP. Some neurons both positive for CGRP and GHS-Rla were labled by fluorogold. Our results not only demonstrate the expression of GHS-R1a in the vagal afferents but also provide the first and direct morphological evidence for its presence in the spinal visceral afferents, and gherin might have a modulatory role in the visceral afferent signaling.

Vanilloid Receptor Type-1 Immunoreactivities in the Mouse Myenteric Plexus: Immunohistochemical and Electrophysiological Study / 체질인류학회지

The vanilloid receptor type-1 (VR1) is a nonselective cation channel activated by capsaicin and can be act as mediator of chemical and physical stimuli that elicit pain. The presence of VR1 in the dorsal root, trigeminal and nodose ganglia has been firmly established, but it unclear in the mouse intestinal wall. The distribution of VR1 receptors in mouse afferent neurons innervating the intestinal tract was investigated by immunohistochemistry. Also small and large intestines were dual-labelled with antibody for VR1 and marker for interstitial cells of Cajal (c-kit). VR1-immunopositive cells were localized on fine fibers in myenteric plexus and expressed weakly myenteric ganglia. The majority of VR1-immunopositive fibers are not colocalized with or apposed to c-kit positive interstitial cells of Cajal. Also electrophysiologically capsaicin had no effect on cultured interstitial cells of Cajal. It is concluded that VR1-immunoreactive intestinal nerves are mainly distributed in myenteric plexus of murine intestinal wall, and vanillod may be not directly related to interstitial cells of Cajal in regulation of intestinal motility.

Vanilloid Receptor Type-1 Immunoreactivities in the Mouse Myenteric Plexus: Immunohistochemical and Electrophysiological Study / 체질인류학회지

The vanilloid receptor type-1 (VR1) is a nonselective cation channel activated by capsaicin and can be act as mediator of chemical and physical stimuli that elicit pain. The presence of VR1 in the dorsal root, trigeminal and nodose ganglia has been firmly established, but it unclear in the mouse intestinal wall. The distribution of VR1 receptors in mouse afferent neurons innervating the intestinal tract was investigated by immunohistochemistry. Also small and large intestines were dual-labelled with antibody for VR1 and marker for interstitial cells of Cajal (c-kit). VR1-immunopositive cells were localized on fine fibers in myenteric plexus and expressed weakly myenteric ganglia. The majority of VR1-immunopositive fibers are not colocalized with or apposed to c-kit positive interstitial cells of Cajal. Also electrophysiologically capsaicin had no effect on cultured interstitial cells of Cajal. It is concluded that VR1-immunoreactive intestinal nerves are mainly distributed in myenteric plexus of murine intestinal wall, and vanillod may be not directly related to interstitial cells of Cajal in regulation of intestinal motility.

Macrostructure of the cranial cervical ganglionar complex and distal vagal ganglion during post natal development in dogs

Doze cães domésticos (Canis familiaris) foram dissecados para o estudo da situação, arranjo e ramificação nervosa do gânglio distal do nervo vago e gânglio cervical cranial. Os gânglios apresentaram-se fusiformes e recobertos pelo músuculo digástrico. Os principais ramos do gânglio cervical cranial observados foram os ramos para a artéria carótida externa e artéria carótida interna. Destacou-se o nervo laringeal cranial como ramo do gânglio distal do nervo vago. O estudo revelou gânglio cervical cranial e o gânglio distal do vago eram estruturas bem desenvolvidas e não encontrou-se diferenças anatômicas entre os gânglios observados em ambos antímeros.

Núcleos do tracto solitário: além da primeira sinapse: funçöes neurovegetativas e hemeostáticas / Nuceus of solitary tract: beyond the first sinapse: autonomic and homeostasis functions

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Localization of sympathetic and sensory nerves innervating heart in the cat using HRP and WGA-HRP as neuronal tracers / 대한해부학회지

The origin of sympathetic and sensory nerves innervating heart in the cat was investigated using HRP (Horseradish peroxidase) and WGA-HRP (Wheat germ agglutinin-horseradish peroxidase) as neuronal tracers. The neural tracers were injected into subepicardial layer and myocardium of the right atrium, left atrium, right ventricle and left ventricle, respectively. Labeled sympathetic neuronal cell bodies were found in superior cervical ganglia, middle cervical ganglia, stellate ganglia and 4th and 5th thoracic ganglia, mainly in middle cervical ganglia and stellate ganglia. Heavier labeled neuronal cell bodies were found in the middle cervical ganglia and stellate ganglia when the neural tracers were injected into left atrium, right ventricle and left ventricle. Labeled sensory neuronal cell bodies were found in nodose ganglia and T1-T6 spinal ganglia, mainly in T1-T5 spinal ganglia. Heavier labeled neuronal cell bodies were found in the nodose ganglia when the neural tracers were injected into left atrium and right ventricle. These results may provide a neuroanatomical data on origin of sensory nerves innervating the heart of the cat.

Immunohistochemical Study of Neuropeptides in Feline Vagal Afferent Neurons / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Nodose ganglion (NG) of the vagus nerve is well known as a sensory ganglion mediated by many neurotransmitters. These neurotransmitters are substance P (SP), calcitonin gene-related peptide (CGRP), cholecystokinin (CCK), neurokinin A (NKA) etc. Controversy exists about other neurotransmitters of NG such as vasoactive intestinal polypeptide (VIP), cholineacetyl transferase (ChAT), and tyrosine hydroxylase (TH). SP is considered to be mainly a sensory neurotransmitter, and ChAT is an enzyme that stimulates acetylcholine synthesis, and is considered to be motor specific. VIP is considered to be a neurotransmitter mainly acting on the parasympathetic system. TH is a rate-limiting enzyme of catecholamine synthesis in the sympathetic system. In this study, we demonstrated the presence of these neurotransmitters in NG. MATERIALS AND METHODS:Seven NG was obtained from five wild cats after ketamine intramuscular anesthesia. Immunohistichemical staining was performed on anti-SP, anti-ChAT, anti-TH, and anti-VIP antibody using Avidin-Biotin-Peroxidae Complex and DAB (diamino benzidine) reaction. RESULTS: 1) Many SP-immunoreactve cells were present in NG, especially in the rostral portion. 2) A few VIP-immunoreactive cells were present, accounting for about 2-5% of all the cells. 3) A few ChAT-immunoreactive cells present. These cells are wide spread in NG, accounting for about 1-3% of all. 4) Many TH-immunoreactive cells present. These cells stained very strongly and were smaller than any other immunoreactive cells. CONCLUSION: We concluded that NG have many neurotransmitters and that their role may be sensory mediation. But we could not exclude the possibility that NG might have other functions other than sensory, so further study should follow.

Distribution and Origin of Nitrergic Innervation of the Canine Laryngeal Ventricle / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Recently, nitric oxide (NO) has been considered to be a neurotransmitter or a signaling molecule in a number of distinct subpopulation of neurons in the central and peripheral nervous systems. This study attempted to define the distribution patterns and quantitative participation according to the origin of nitrergic innervation in the canine laryngeal ventricles of eight adult dogs. MATERIALS AND METHODS: The nitrergic innervation in the intralaryngeal, superior cervical and nodose ganglion to the laryngeal ventricle were investigated by using double labelled neuronal NO synthase (nNOS) immunocytochemistry combined with a retrograde tracer, cholera toxin subunit B-conjugated horseradish peroxidase (CTB-HRP). RESULTS: NO is suggested to participate in parasympathetic, sympathetic and sensory innervation. Intralaryngeal ganglion is the main source of nitrergic innervation in the canine laryngeal ventricle. The proportions of the nitrergic innervation in the intralaryngeal ganglion, superior cervical ganglion, and nodose ganglion to the canine laryngeal ventricle were 63.1%, 37.7%, 4.9% respectively. CONCLUSION: NO originating from the intralaryngeal ganglion in a canine laryngeal ventricle may play an important role in controlling the laryngeal gland secretion and in regulating the blood flow by modulating the classical parasympathetic cholinergic neurotransmitter as like a neuronal messenger or comediator. NO also may participate in the same role through the sympathetic innervation of superior cervical ganglion: however, NO originating from intralaryngeal ganglion may play more important role than that from superior cervical ganglion. Many neurons of nodose ganglion have demonstrated to have nNOS, but might be less involved in the ventricular sensory innervation.

Localization of Sensory Neurons Innervating the Rat Intestine Using the Cholera Toxin B Subunit(CTB) and Wheat Germ Agglutinin-Horseradish Peroxidase(WGA-HRP) / 영남의대학술지

The local arrangement of sensory nerve cell bodies and nerve fibers in the brain stem, spinal ganglia and nodose ganglia were observed following injection of cholera toxin B subunit(CTB) and wheat germ agglutinin-horseradish peroxidase(WGA-HRP) into the rat intestine. The tracers were injected in the stomach(anterior and posterior portion), duodenum, jejunum, ileum, cecum, ascending colon or descending colon. After survival times of 48-96 hours, the rats were perfused and their brain, spinal and nodose ganglia were frozen sectioned(40microM). These sectiones were stained by CTB immunohistochemical and HRP histochemical staining methods and observed by dark and light microscopy. The results were as follows: 1. WGA-HRP labeled afferent terminal fields in the brain stem were seen in the stomach and cecum, and CTB labeled afferent terminal fields in the brain stem were seen in all parts of the intestine. 2. Afferent terminal fields innervating the intestine were heavily labeled bilaterally gelalinous part of nucleus of tractus solitarius(gelNTS), dorsomedial part of gelNTS, commissural part of NTS(comNTS), medial part of NTS(medNTS), wall of the fourth ventricle, ventral border of area postrema and comNTS in midline dorsal to the central canal. 3. WGA-HRP labeled sensory neurons were observed bilaterally within the spinal ganglia, and labeled sensory neurons innervating the stomach were observed in spinal ganglia T2-L1 and the most numerous in spinal ganglia T8-9. 4. Labeled sensory neurons innervating the duodenum were observed in spinal ganglia T6-L2 and labeled cell number were fewer than the other parts of the intestines. 5. Labeled sensory neurons innervating the jejunum were observed in spinal ganglia T6-L2 and the most numerous area in the spinal ganglia were T12 in left and T13 in right. 6. Labeled sensory neurons innervating the ileum were observed in spinal ganglia T6-L2 and the most numerous area in the spinal ganglia were T11 in left and L1 in right. 7. Labeled sensory neurons innervating the cecum were observed in spinal ganglia T7-L2 and the most numerous area in the spinal ganglia were T11 in left and T11-12 in right. 8. Labeled sensory neurons innervating the ascending colon were observed in spinal ganglia T7-L2 in left, and T9-L4 in right. The most numerous area in the spinal ganglia were T9 in left and T11 in right. 9. Labeled sensory neurons innervating the descending colon were observed in spinal ganglia T9-L2 in left, and T6-L2 in right. The most numerous area in the spinal ganglia were T13 in left and L1 in right. 10. WGA-HRP labeled sensory neurons were observed bilaterally within the nodose ganglia, and the most numerous labeled sensory neurons innervating the abdominal organs were observed in the stomach. 11. The number of labeled sensory neurons within the nodose ganglia innervating small and large intestines were fewer than that of labeled sensory neurons innervating stomach These results indicated that area of sensory neurons innervated all parts of intestines were bilaterally gelatinous part of nucleus tractus solitarius(gelNTS), dorsomedial part of gelNTS, commissural part of NTS(comNTS), medial part of NTS, wall of the fourth ventricle, ventral border of area postrema and com NTS in midline dorsal to the central canal within brain stem, spinal ganglia T2-L4, and nodose ganglia. Labeled sensory neurons innervating the intestines except the stomach were observed in spinal ganglia T6-L4. The most labeled sensory neurons from the small intestine to large intestine came from middle thoracic spinal ganglia to upper lumbar spinal ganglia.

Glutamate-Immunoreactive Neurons in the Nucleus Ambiguus of the Cat: Comparison after Cholera Toxin beta-subunit Injection to the Nodose Ganglion / 대한이비인후과학회지

Though the existence of glutamate-immunoreactive(GL-IR) neurons has been suggested in the nucleus ambiguous(NA) by immunocytochemistry, information regarding the distribution of neurons containing glutamate as a neurotransmitter has been to be elucidated. The author focused on distribution and morphology of GL-IR neurons in the NA, which were compared with cholera toxin beta-subunit(CTB) labeled neurons after its injection to the nodose ganglion(NG) in the cat. The results showed that the majority of neurons in the NA were immunoreactive to excitatory neurotransmitter glutamate, and they seemed to be distributed evenly without any special area of predilection or grouping pattern. The cellular shape was predominantly multipolar. GL-IR neurons showed some similarity in morphology and distribution pattern with CTB labeled cells.