scholarly journals Sex-steroid-dependent plasticity of brain-stem autonomic circuits

2020 ◽  
Vol 319 (1) ◽  
pp. R60-R68
Author(s):  
Erica L. Littlejohn ◽  
Stephanie Fedorchak ◽  
Carie R. Boychuk
Keyword(s):  
Nervous System ◽  
Brain Stem ◽  
Sex Hormones ◽  
Nucleus Tractus Solitarius ◽  
Critical Role ◽  
Vagal Afferents ◽  
Motor Nucleus ◽  
Peripheral Sensory ◽  
The Brain

In the central nervous system (CNS), nuclei of the brain stem play a critical role in the integration of peripheral sensory information and the regulation of autonomic output in mammalian physiology. The nucleus tractus solitarius of the brain stem acts as a relay center that receives peripheral sensory input from vagal afferents of the nodose ganglia, integrates information from within the brain stem and higher central centers, and then transmits autonomic efferent output through downstream premotor nuclei, such as the nucleus ambiguus, the dorsal motor nucleus of the vagus, and the rostral ventral lateral medulla. Although there is mounting evidence that sex and sex hormones modulate autonomic physiology at the level of the CNS, the mechanisms and neurocircuitry involved in producing these functional consequences are poorly understood. Of particular interest in this review is the role of estrogen, progesterone, and 5α-reductase-dependent neurosteroid metabolites of progesterone (e.g., allopregnanolone) in the modulation of neurotransmission within brain-stem autonomic neurocircuits. This review will discuss our understanding of the actions and mechanisms of estrogen, progesterone, and neurosteroids at the cellular level of brain-stem nuclei. Understanding the complex interaction between sex hormones and neural signaling plasticity of the autonomic nervous system is essential to elucidating the role of sex in overall physiology and disease.

scholarly journals Glymphatics: A Transformative Development in Medical Neuroscience Relevant to Injuries in Military Central Nervous System

2021 ◽  
Author(s):  
James Meyerhoff ◽  
Nabarun Chakraborty ◽  
Rasha Hammamieh
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Sleep Deprivation ◽  
Brain Edema ◽  
Critical Role ◽  
Spatial Relationship ◽  
Military Operations ◽  
Glymphatic System ◽  
The Brain

ABSTRACT Introduction The glia-operated glymphatic system, analogous to but separate from the lymphatics in the periphery, is unique to brain and retina, where it is very closely aligned with the arteriolar system. This intimate relationship leads to a “blood vessel like” distribution pattern of glymphatic vessels in the brain. The spatial relationship of glymphatics, including their essential component aquaporin-4 with vascular pericytes of brain arterioles is critical to functionality and is termed “polarization”. Materials and Methods We review the available literature on the factors affecting the resting state of glymphatics under normal conditions, including the important role of sleep in supporting normal glymphatic function (including waste removal) as well as the critical role of “polarization” under normal conditions. We then examine the effects of traumatic brain injury (TBI) or seizures on the glymphatic system and its state of “polarization”. Results Injury, such as TBI, can disrupt polarization resulting in “depolarization” leading to brain edema. Conclusion Damage to the glymphatic system might explain the brain edema so often seen following TBI or other insult. Moreover, similar damage should be expected in response to seizures, which can often be associated with chemical exposures as well as with TBI. Military operations, whether night operations or continuous operations, quite often impose limitations on sleep. As glymphatic function is sleep-dependent, sleep deprivation alone could compromise glymphatic function, as well, and might in addition, explain some of the well-known performance deficits associated with sleep deprivation. Possible effects of submarine and diving operations, chemical agents (including seizures), as well as high altitude exposure and other threats should be considered. In addition to the brain, the retina is also served and protected by the glymphatic system. Accordingly, the effect of military-related risks (e.g., exposure to laser or other threats) to retinal glymphatic function should also be considered. An intact glymphatic system is absolutely essential to support normal central nervous system functionality, including cognition. This effects a broad range of military threats on brain and retinal glymphatics should be explored. Possible preventive and therapeutic measures should be proposed and evaluated, as well.

Neurons in the dorsal motor nucleus of the vagus may integrate vagal and spinal information from the GI tract

1995 ◽  
Vol 268 (5) ◽  
pp. G780-G790 ◽  
Author(s):  
W. E. Renehan ◽  
X. Zhang ◽  
W. H. Beierwaltes ◽  
R. Fogel
Keyword(s):  
Brain Stem ◽  
Vagal Afferents ◽  
High Threshold ◽  
Motor Nucleus ◽  
Potential Contribution ◽  
Gi Tract ◽  
Dorsal Motor Nucleus ◽  
Efferent Neurons ◽  
Spinal Afferents ◽  
The Brain

Previous investigations have provided evidence that the activity of parasympathetic efferent neurons in the dorsal motor nucleus of the vagus (DMNV) may be influenced by either vagal afferent or spinal input from the gastrointestinal (GI) tract. Many questions remain, however, regarding the nature of this input and its integration by the brain stem. The present study was designed to examine one important aspect of this issue: the potential contribution of the spinal input to the brain stem in the generation of the response properties of intestine-sensitive neurons in the DMNV. Using intracellular recording and labeling techniques in adult rats, we found that ascending spinal pathways were capable of conveying both low- and high-threshold visceral information to the DMNV. We also determined that the neurons in the nucleus of the solitary tract failed to respond to intestinal distention when the vagal afferents to the brain stem had been severed, suggesting that the spinal projections terminate directly on the DMNV neurons. These data lend support to the emerging hypothesis that the spinal afferents that accompany the abdominal splanchnics are capable of responding to both innocuous and noxious stimuli. The results also suggest that the neurons in the DMNV play a larger role in the integration of visceral sensory information than was previously realized.

scholarly journals Role of the brain stem in tibial inhibition of the micturition reflex in cats

2015 ◽  
Vol 309 (3) ◽  
pp. F242-F250 ◽  
Author(s):  
Matthew C. Ferroni ◽  
Rick C. Slater ◽  
Bing Shen ◽  
Zhiying Xiao ◽  
Jicheng Wang ◽  
...  
Keyword(s):  
Overactive Bladder ◽  
Brain Stem ◽  
Critical Role ◽  
Bladder Capacity ◽  
Saline Control ◽  
Tibial Nerve Stimulation ◽  
Normal Bladder ◽  
Decerebrate Cats ◽  
The Brain

This study examined the role of the brain stem in inhibition of bladder reflexes induced by tibial nerve stimulation (TNS) in α-chloralose-anesthetized decerebrate cats. Repeated cystometrograms (CMGs) were performed by infusing saline or 0.25% acetic acid (AA) to elicit normal or overactive bladder reflexes, respectively. TNS (5 or 30 Hz) at three times the threshold (3T) intensity for inducing toe movement was applied for 30 min between CMGs to induce post-TNS inhibition or applied during the CMGs to induce acute TNS inhibition. Inhibition was evident as an increase in bladder capacity without a change in amplitude of bladder contractions. TNS applied for 30 min between saline CMGs elicited prolonged (>2 h) poststimulation inhibition that significantly ( P < 0.05) increased bladder capacity to 30–60% above control; however, TNS did not produce this effect during AA irritation. TNS applied during CMGs at 5 Hz but not 30 Hz significantly ( P < 0.01) increased bladder capacity to 127.3 ± 6.1% of saline control or 187.6 ± 5.0% of AA control. During AA irritation, naloxone (an opioid receptor antagonist) administered intravenously (1 mg/kg) or directly to the surface of the rostral brain stem (300–900 μg) eliminated acute TNS inhibition and significantly ( P < 0.05) reduced bladder capacity to 62.8 ± 22.6% (intravenously) or 47.6 ± 25.5% (brain stem application). Results of this and previous studies indicate 1) forebrain circuitry rostral to the pons is not essential for TNS inhibition; and 2) opioid receptors in the brain stem have a critical role in TNS inhibition of overactive bladder reflexes but are not involved in inhibition of normal bladder reflexes.

scholarly journals The Role of Neuropeptide Y in the Nucleus Accumbens

2021 ◽  
Vol 22 (14) ◽  
pp. 7287
Author(s):  
Masaki Tanaka ◽  
Shunji Yamada ◽  
Yoshihisa Watanabe
Keyword(s):  
Nervous System ◽  
Nucleus Accumbens ◽  
Neuropeptide Y ◽  
Emotional Behavior ◽  
Characteristic Functions ◽  
Receptor Subtypes ◽  
Neuroendocrine Mechanisms ◽  
Fear And Anxiety ◽  
The Brain

Neuropeptide Y (NPY), an abundant peptide in the central nervous system, is expressed in neurons of various regions throughout the brain. The physiological and behavioral effects of NPY are mainly mediated through Y1, Y2, and Y5 receptor subtypes, which are expressed in regions regulating food intake, fear and anxiety, learning and memory, depression, and posttraumatic stress. In particular, the nucleus accumbens (NAc) has one of the highest NPY concentrations in the brain. In this review, we summarize the role of NPY in the NAc. NPY is expressed principally in medium-sized aspiny neurons, and numerous NPY immunoreactive fibers are observed in the NAc. Alterations in NPY expression under certain conditions through intra-NAc injections of NPY or receptor agonists/antagonists revealed NPY to be involved in the characteristic functions of the NAc, such as alcohol intake and drug addiction. In addition, control of mesolimbic dopaminergic release via NPY receptors may take part in these functions. NPY in the NAc also participates in fat intake and emotional behavior. Accumbal NPY neurons and fibers may exert physiological and pathophysiological actions partly through neuroendocrine mechanisms and the autonomic nervous system.

scholarly journals Role of Nitric Oxide in Regulation of Brain Stem Circulation during Hypotension

1997 ◽  
Vol 17 (10) ◽  
pp. 1089-1096 ◽  
Author(s):  
Kazunori Toyoda ◽  
Kenichiro Fujii ◽  
Setsuro Ibayashi ◽  
Tetsuhiko Nagao ◽  
Takanari Kitazono ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Brain Stem ◽  
Topical Application ◽  
Basilar Artery ◽  
Group Versus ◽  
Control Group ◽  
Cranial Window ◽  
Severe Hypotension ◽  
The Brain

We tested the hypothesis that nitric oxide (NO) plays a role in CBF autoregulation in the brain stem during hypotension. In anesthetized rats, local CBF to the brain stem was determined with laser-Doppler flowmetry, and diameters of the basilar artery and its branches were measured through an open cranial window during stepwise hemorrhagic hypotension. During topical application of 10−5 mol/L and 10−4 mol/L Nω-nitro-L-arginine (L-NNA), a nonselective inhibitor of nitric oxide synthase (NOS), CBF started to decrease at higher steps of mean arterial blood pressure in proportion to the concentration of L-NNA in stepwise hypotension (45 to 60 mm Hg in the 10−5 mol/L and 60 to 75 mm Hg in the 10−4 mol/L L-NNA group versus 30 to 45 mm Hg in the control group). Dilator response of the basilar artery to severe hypotension was significantly attenuated by topical application of L-NNA (maximum dilatation at 30 mm Hg: 16 ± 8% in the 10−5 mol/L and 12 ± 5% in the 10−4 mol/L L-NNA group versus 34 ± 4% in the control group), but that of the branches was similar between the control and L-NNA groups. Topical application of 10−5 mol/L 7-nitro indazole, a selective inhibitor of neuronal NOS, did not affect changes in CBF or vessel diameter through the entire pressure range. Thus, endothelial but not neuronal NO seems to take part in the regulation of CBF to the the brain stem during hypotension around the lower limits of CBF autoregulation. The role of NO in mediating dilatation in response to hypotension appears to be greater in large arteries than in small ones.

A critical role for central vasopressin in regulation of fever during bacterial infection

1992 ◽  
Vol 263 (6) ◽  
pp. R1235-R1240
Author(s):  
R. A. Cridland ◽  
N. W. Kasting
Keyword(s):  
Body Temperature ◽  
Arginine Vasopressin ◽  
Continuous Measurement ◽  
Critical Role ◽  
Experimental Models ◽  
Bacterial Endotoxins ◽  
Chronic Infusion ◽  
Live Bacteria ◽  
The Brain

Previous investigations on the antipyretic properties of arginine vasopressin have used bacterial endotoxins or pyrogens to induce fever. Because these experimental models of fever fail to mimic all aspects of the responses to infection, we felt it was important to examine the role of endogenously released vasopressin as a neuromodulator in febrile thermoregulation during infection. Therefore the present study examines the effects of chronic infusion of a V1-receptor antagonist or saline (via osmotic minipumps into the ventral septal area of the brain) on a fever induced by injection of live bacteria. Telemetry was used for continuous measurement of body temperature in the awake unhandled rat. Animals infused with the V1-antagonist exhibited fevers that were greater in duration compared with those of saline-infused animals. These results support the hypothesis that vasopressin functions as an antipyretic agent or fever-reducing agent in brain. Importantly, they suggest that endogenously released vasopressin may play a role as a neuromodulator in natural fever.

Signaling the brain in systemic inflammation: which vagal branch is involved in fever genesis?

1998 ◽  
Vol 275 (1) ◽  
pp. R63-R68 ◽  
Author(s):  
Christopher T. Simons ◽  
Vladimir A. Kulchitsky ◽  
Naotoshi Sugimoto ◽  
Louis D. Homer ◽  
Miklos Székely ◽  
...  
Keyword(s):  
Vagal Afferents ◽  
Male Wistar Rats ◽  
Food Retention ◽  
Maximal Rise ◽  
Fever Response ◽  
Colonic Temperature ◽  
Postsurgical Recovery ◽  
The Brain ◽  
Bladder Urine

Recent evidence has suggested a role of abdominal vagal afferents in the pathogenesis of the febrile response. The abdominal vagus consists of five main branches (viz., the anterior and posterior celiac branches, anterior and posterior gastric branches, and hepatic branch). The branch responsible for transducing a pyrogenic signal from the periphery to the brain has not as yet been identified. In the present study, we address this issue by testing the febrile responsiveness of male Wistar rats subjected to one of four selective vagotomies: celiac (CBV), gastric (GBV), hepatic (HBV), or sham (SV). In the case of CBV, GBV, and HBV, only the particular vagal branch(es) was cut; for SV, all branches were left intact. After the postsurgical recovery (26–29 days), the rats had a catheter implanted into the jugular vein. On days 29–32, their colonic temperature (Tc) responses to a low dose (1 μg/kg) of Escherichia colilipopolysaccharide (LPS) were studied. Three days later, the animals were subjected to a 24-h food and water deprivation, and the effectiveness of the four vagotomies to induce gastric food retention, pancreatic hypertrophy, and impairment of the portorenal osmotic reflex was assessed by weighing the stomach and pancreas and measuring the specific gravity of bladder urine, respectively. Stomach mass, pancreas mass, and urine density successfully separated the four experimental groups into four distinct clusters, thus confirming that each type of vagotomy had a different effect on the indexes measured. The Tc responses of SV, CBV, and GBV rats to LPS did not differ and were characterized by a latency of ∼40 min and a maximal rise of 0.7 ± 0.1, 0.6 ± 0.1, and 0.9 ± 0.2°C, respectively. The fever response of the HBV rats was different; practically no Tc rise occurred (0.1 ± 0.2°C). The HBV appeared to be the only selective abdominal vagotomy affecting the febrile responsiveness. We conclude, therefore, that the hepatic vagus plays an important role in the transduction of a pyrogenic signal from the periphery to the brain.

scholarly journals Activation of central 5-HT2A receptor in brain inhibited the seizure-induced respiratory arrest in the DBA/1 mouse SUDEP model

2020 ◽  
Author(s):  
Yue Shen ◽  
HaiXiang Ma ◽  
XiTing Lian ◽  
LeYuan Gu ◽  
Qian Yu ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Drug Resistance ◽  
Nervous System ◽  
Underlying Mechanism ◽  
Respiratory Arrest ◽  
Acoustic Stimulation ◽  
Unexpected Death ◽  
Anti Epileptic Drug ◽  
The Brain

AbstractSudden unexpected death in epilepsy (SUDEP) is the fatal cause leading to the death of epilepsy patients with anti-epileptic drug resistance. However, the underlying mechanism of SUDEP remains to be elusive. Our previous study demonstrated that enhancement of serotonin (5-HT) synthesis by intraperitoneal (IP) injection of 5-hydroxytryptophan in brain significantly reduced the incidence of seizure-induced respiratory arrest (S-IRA) in DBA/1 mice SUDEP models. Given that 5-HT2A receptor (5-HT2AR) acts an important role in mediating respiration system in brain, we hypothesized that 5-HT2AR is of great significance to modulate S-IRA and SUDEP. To test this hypothesis, we examined whether the decreased incidence S-IRA evoked by either acoustic stimulation or PTZ by blocking 5-HT2AR by administration with ketanserin (KET), a selective antagonist of 5HT2AR, in DBA/1 mice SUDEP models to test the role of 5-HT2AR modulating S-IRA. Our results suggested that the decreased incidence of S-IRA by 5-Hydroxytryptophan (5-HTP), a precursor for central nervous system (CNS) serotonin (5-HT) synthesis, was significantly reversed by IP and intracerebroventricularly (ICV) injection of ketanserin in our models. Thus, our data suggested that 5-HT2AR in the brain may be a potential and specific target to prevent SUDEP.

scholarly journals Sex Differences and the Influence of Sex Hormones on Cognition through Adulthood and the Aging Process

2018 ◽  
Vol 8 (9) ◽  
pp. 163 ◽  
Author(s):  
Caroline Gurvich ◽  
Kate Hoy ◽  
Natalie Thomas ◽  
Jayashri Kulkarni
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Cognitive Functioning ◽  
Sex Hormones ◽  
Reproductive Function ◽  
Health And Disease ◽  
And Function ◽  
The Brain

Hormones of the hypothalamic-pituitary-gonadal (HPG) axis that regulate reproductive function have multiple effects on the development, maintenance and function of the brain. Sex differences in cognitive functioning have been reported in both health and disease, which may be partly attributed to sex hormones. The aim of the current paper was to provide a theoretical review of how sex hormones influence cognitive functioning across the lifespan as well as provide an overview of the literature on sex differences and the role of sex hormones in cognitive decline, specifically in relation to Alzheimer’s disease (AD). A summary of current hormone and sex-based interventions for enhancing cognitive functioning and/or reducing the risk of Alzheimer’s disease is also provided.

Dr. Feig Replies

PEDIATRICS ◽  
1977 ◽  
Vol 59 (1) ◽  
pp. 145-145
Author(s):  
Stephen A. Feig
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Radiation Therapy ◽  
Brain Stem ◽  
Metastatic Disease ◽  
Clinical Course ◽  
Convincing Evidence ◽  
Additional Radiation ◽  
The Brain ◽  
Bony Erosion

Thank you for the opportunity to reply to the letter of Drs. McWilliams and Maurer. We were truly perplexed by the presentation of the meningeal metastases in the reported patient. Lacking convincing evidence of central nervous system metastatic disease or bony erosion of the skull, we were loath to apply chemotherapy, which might have aggravated his clinical course and would have been of doubtful efficacy in any event. Additional radiation therapy was felt to be inadvisable because, in the opinion of our radiotherapists, the patient had been treated originally with a dose that closely approached the tolerance of the brain stem.

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