Circuit-Specific Control of Blood Pressure by PNMT-Expressing Nucleus Tractus Solitarii Neurons / 神经科学通报·英文版

The nucleus tractus solitarii (NTS) is one of the morphologically and functionally defined centers that engage in the autonomic regulation of cardiovascular activity. Phenotypically-characterized NTS neurons have been implicated in the differential regulation of blood pressure (BP). Here, we investigated whether phenylethanolamine N-methyltransferase (PNMT)-expressing NTS (NTSPNMT) neurons contribute to the control of BP. We demonstrate that photostimulation of NTSPNMT neurons has variable effects on BP. A depressor response was produced during optogenetic stimulation of NTSPNMT neurons projecting to the paraventricular nucleus of the hypothalamus, lateral parabrachial nucleus, and caudal ventrolateral medulla. Conversely, photostimulation of NTSPNMT neurons projecting to the rostral ventrolateral medulla produced a robust pressor response and bradycardia. In addition, genetic ablation of both NTSPNMT neurons and those projecting to the rostral ventrolateral medulla impaired the arterial baroreflex. Overall, we revealed the neuronal phenotype- and circuit-specific mechanisms underlying the contribution of NTSPNMT neurons to the regulation of BP.

A Neural Circuit Mechanism Controlling Breathing by Leptin in the Nucleus Tractus Solitarii / 神经科学通报·英文版

Leptin, an adipocyte-derived peptide hormone, has been shown to facilitate breathing. However, the central sites and circuit mechanisms underlying the respiratory effects of leptin remain incompletely understood. The present study aimed to address whether neurons expressing leptin receptor b (LepRb) in the nucleus tractus solitarii (NTS) contribute to respiratory control. Both chemogenetic and optogenetic stimulation of LepRb-expressing NTS (NTSLepRb) neurons notably activated breathing. Moreover, stimulation of NTSLepRb neurons projecting to the lateral parabrachial nucleus (LPBN) not only remarkably increased basal ventilation to a level similar to that of the stimulation of all NTSLepRb neurons, but also activated LPBN neurons projecting to the preBötzinger complex (preBötC). By contrast, ablation of NTSLepRb neurons projecting to the LPBN notably eliminated the enhanced respiratory effect induced by NTSLepRb neuron stimulation. In brainstem slices, bath application of leptin rapidly depolarized the membrane potential, increased the spontaneous firing rate, and accelerated the Ca2+ transients in most NTSLepRb neurons. Therefore, leptin potentiates breathing in the NTS most likely via an NTS-LPBN-preBötC circuit.

Neuronal and endocrine regulation of food intake / 药学实践杂志

The neuronal and hormonal regulations of food intake expand our knowledge about energy balance .The cen-tral nervous system integrates endocrine signals to regulate food intake and energy consumption .The nervous system and endo-crine system interact with each other to regulate feeding behavior .This paper was a review of the neuronal and endocrine regu-lation of food intake ,and offered a revealing insight for the study and treatment of metabolic disorders .

Multi-effect of central nitric oxide on cardiovascular activity / 第二军医大学学报

Objective To observe the effect of nitric oxide(NO)on cardiovascular activities in the nucleus tractus solitarii (NTS) and the rostral ventrolateral medulla (RVLM), so as to understand the role of central NO in cardiovascular regulation. Methods The changes of blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were observed following treatments with increased or decreased NO in the NTS and RVLM of anaesthetized SD rats. Results Microinjection of the NO precusor L-arginine (L-Arg, 2 nmol in 50 nl) into the NTS, a key relay of cardiovascular reflex transmission, produced significant decreases in BP, HR, and RSNA (P<0. 05), and injection of NO synthase inhibitor NG-nitro-L-arginine methyl ester(L-NAME, 10 nmol in 50 nl) into the NTS produced significant increases in these cardiovascular parameters (P<0. 05). However, injection of L-Arg (2 nmol in 100 nl) into the RVLM, a key region controlling sympathetic outflow, significantly increased basal BP, HR, and RSNA (P<0. 05), and injection of L-NAME (10 nmol in 100 nl) into the RVLM showed a cardiovascular inhibition effect (P<0. 05). Conclusion NO exhibits different effects in different cardiovascular centers, suggesting that it plays a special role in maintaining the basal cardiovascular activity.

Cardiovascular and autonomic modulation by the central nervous system after aerobic exercise training

The autonomic nervous system plays a key role in maintaining homeostasis under normal and pathological conditions. The sympathetic tone, particularly for the cardiovascular system, is generated by sympathetic discharges originating in specific areas of the brainstem. Aerobic exercise training promotes several cardiovascular adjustments that are influenced by the central areas involved in the output of the autonomic nervous system. In this review, we emphasize the studies that investigate aerobic exercise training protocols to identify the cardiovascular adaptations that may be the result of central nervous system plasticity due to chronic exercise. The focus of our study is on some groups of neurons involved in sympathetic regulation. They include the nucleus tractus solitarii, caudal ventrolateral medulla and the rostral ventrolateral medulla that maintain and regulate the cardiac and vascular autonomic tonus. We also discuss studies that demonstrate the involvement of supramedullary areas in exercise training modulation, with emphasis on the paraventricular nucleus of the hypothalamus, an important area of integration for autonomic and neuroendocrine responses. The results of these studies suggest that the beneficial effects of physical activity may be due, at least in part, to reductions in sympathetic nervous system activity. Conversely, with the recent association of physical inactivity with chronic disease, these data may also suggest that increases in sympathetic nervous system activity contribute to the increased incidence of cardiovascular diseases associated with a sedentary lifestyle.

Effects of oropharyngeal taste stimuli in the restoration of the fasting-induced activation of the HPA axis in rats

INTRODUCTION: This study examined the regulatory mechanism underlying the meal-induced changes in the hypothalamic-pituitary-adrenal gland (HPA) axis activity. MATERIALS AND METHODS: Male Sprague-Dawley rats (250-300 g) were hired for two different experiments as follows; 1) rats received either 8% sucrose or 0.2% saccharin ad libitum after 48 h of food deprivation with the gastric fistula closed (real feeding) or opened (sham feeding). 2). rats received 5 ml of intra-oral infusion with 0.2% saccharin or distilled water after 48 h of food deprivation. One hour after food access, all rats were sacrificed by a transcardiac perfusion with 4% paraformaldehyde. The brains were processed for c-Fos immunohistochemistry and the cardiac blood was collected for the plasma corticosterone assay. RESULTS: Real feedings with sucrose or saccharin and sham feeding saccharin but not sucrose, following food deprivation decreased the plasma corticosterone level. c-Fos expression in the nucleus tractus of solitarius (NTS) of the fasted rats was increased by the consumption of sucrose but not saccharin, regardless of the feeding method. On the other hand, the consumption of sucrose or saccharin with real feeding but not the sham, induced c-Fos expression in the paraventricular nucleus (PVN) of the fasted rats. The intra-oral infusion with saccharin or water decreased the plasma corticosterone level of the fasted rats. Intra-oral water infusion increased c-Fos expression in both the PVN and NTS, but saccharin only in the NTS in the fasted rats. CONCLUSION: Neither restoration of the fasting-induced elevation of plasma corticosterone nor the activation of neurons in the PVN and NTS after refeeding requires the palatability of food or the post-ingestive satiety and caloric load. In addition, neuronal activation in the hypothalamic PVN may not be an implication in the restoration of the fasting-induced elevation of the plasma corticosterone by oropharyngeal stimuli of palatable food.

Effects of 5-HT and Norepinephrine on the Neuronal Activities of the Nucleus Tractus Solitaril in Medullary Slices / 第二军医大学学报

The relationship between 5-HT receptor and a-adrenoceptor was investigated in rat medullary slice preparations. In 57 nucleus tractus solitarii (NTS) neurons, 47 (82.5%) responded to both serotonin (5-HT) and norepinephrine (NE). After synapse transmission was blocked by perfusion of artificial cerebrospinal fluid (ACSF) with low calcium and high magnesium, 5 in 8 neurons were still sensitive to both 5-HT and NE. On the other hand, 3 in 5 neurons responding only to 5-HT or NA were sensitive to both 5-HT and NE after the synapse transmission blockage. In some neurons which exhibited excitatory or inhibitory responses to 5-HT or NE alone, the responses were inversed when perfused with 5-HT and NE in combination. These results suggest that there may exist an inhibitory interaction between 5-HT receptors and a-adrenoceptors in NTS and that most 5-NT and a-adrenoceptors coexist in the same NTS neurons.

SOMATOSTATIN-CONTAINING NEURONS AND NERVE FIBERS IN ThE NUCLEUS TRACTUS SOLITARII——A IMMUNOELECTRON MICROSCOPIC STUDY / 解剖学报

Somatostatin-containing neurons and nerve fibers in the commissural subnucleus of the nucleus tractus solitarii(NTS) of the rat were studied by means of munoelectron microscopy. The results showed that somatostatin-like immunoreactive positive neurons are medium or small cells, fusiform or elliptical. Somatostatin- like immunoreactive positive axons are unmyelinated,and mainly form passage or terminal synapses. Somatostatin-positive cell bodies themselves have not been obser- ved to form synapses with somatostatin-positive fibers,but their dendrites may receive innervation from immunoreactive-negative fibers by axo-dendritic synapses.

THE INDIRECT PATHWAY OF THE SOMATIC AFFERENT ELEMENTS FROM TRIGEMINAL NERVE TO NUCLEUS TRACTUS SOLITARII——A LIGHT AND ELECTRON MICROSCOPIC HRP TRANSGANGLIONIC AND RETROGRADE TRACING STUDY / 解剖学报

The indirect pathway of the somatic afferent elements from trigeminal nerve (TGN) to nucleus tractus solitarii (NTS) was studied with the light and electron microscopic HRP transganglionic and retrograde tracing. After HRP was injected into NTS at the level of obex, the retrogradely labeled cells were mainly found in the interstitial nucleus buried in the spinal tract of TGN along caudal subnucleus. The interstitial nucleus was also the terminating area of the primary afferent fibers of lingual and inferior orbital nerves. Under electron microscope, it was found that the primary afferent terminals of lingual and inferior orbital nerves formed synapses on the dendrites of neurons in the interstitial nucleus. Moreover, in cellular architecture, the interstitial nucleus and the superficial laminae of the caudal nucleus of TGN were similar and continuous with each other. Hence, the pathway from the TGN to NTS via the interstitial nucleus is consisted of two neurons and the sensations transmitted through this pathway may be considered to be somatic. It is presumed that this pathway composed of two neurons might modulate the visceral afferent function in NTS when certain points in the skin area innervated by TGN were acupunctured.

PROJECTIONS FROM THE NUCLEUS TRACTUS SOLITARII AND THE NUCLEI PARABRACHIALES TO THE NUCLEUS ACCUMBENS IN THE RAT——A HRP TRACING STUDY / 解剖学报

The projections from the nucleus tractus solitarii (NTS) and the nuclei parabrachiales (PB) to the nucleus accumbens (Acc) in the rat have been visulized using anterograde and retrograde HRP tracing techniques. After injecting HRP into the Acc, retrogradely labelled neurons were observed in bilateral PB and NTS with ipsilateral predominance. The labelled neurons were concentrated in the following areas of the PB and NTS: the waist area of the caudal PB, the external subnucleus and other part of the nucleus medialis parabrachialis (PBm), the external, central, and internal subnuclei of the nucleus lateralis parabrachialis (PB1) and the medial subnucleus of the caudal NTS (NTSm). After injecting HRP into the NTSm and commissural nucleus of the NTS, anterogradely labelled terminals were found bilaterally in the PBm and the ventral 3/4 area of the PB1. The densest sites occupied the waist area, the external, central, and internal subnuclei of the PB1. The density of the labelled terminals on the ipsilateral side was little higher than that on the contralateral side. The results indicate that there are two possible pathways from the NTS to the Acc, the one is the direct projection from the medial subnucleus of the caudal NTS to the Ace, the other is an indirect one, i. e. from the medial subnucleus and commissural nucleus of the caudal NTS to the waist area of the caudal PB, the external subnucleus, the dorsal part of the PBm, the external, central, and internal subnuclei of the PB1, where the NTS projection is. presumed to be relayed, and then, project from the PB to the Acc. This connection may be involved in the neural regulation of visceral and locomotor activities.