(In)activity-dependent alterations in resting and reflex control of splanchnic sympathetic nerve activity

Mischel, Nicholas; Mueller, Patrick

doi:10.1152/japplphysiol.00961.2011

Cited by 40 publications

(120 citation statements)

References 70 publications

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“…This anatomical finding underpins previous functional studies demonstrating that NMDA and alpha-amino-3- hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) types of ionotropic glutamate receptors are important in the RVLM in control of sympathetic outflow and blood pressure regulation under normal and pathophysiological conditions (Bardgett et al, 2010; Lin et al, 2006; Mao and Abdel-Rahman, 1995; Mischel and Mueller, 2011; Sun and Reis, 1995). …”

Section: Bulbospinal Catecholamine Neurons In the Rostral Ventral Medsupporting

confidence: 74%

Immunoreactivity for the NMDA NR1 subunit in bulbospinal catecholamine and serotonin neurons of rat ventral medulla

Llewellyn‐Smith¹,

Mueller²

2013

Autonomic Neuroscience

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Bulbospinal neurons in the ventral medulla play important roles in the regulation of sympathetic outflow. Physiological evidence suggests that these neurons are activated by N-methyl-D-aspartate (NMDA) and non-NMDA subtypes of glutamate receptors. In this study, we examined bulbospinal neurons in the ventral medulla for the presence of immunoreactivity for the NMDA NR1 subunit, which is essential for NMDA receptor function. Rats received bilateral injections of cholera toxin B into the tenth thoracic spinal segment to label bulbospinal neurons. Triple immunofluorescent labelling was used to detect cholera toxin B with a blue fluorophore, NR1 with a red fluorophore and either tyrosine hydroxylase or tryptophan hydroxylase with a green fluorophore. In the rostral ventrolateral medulla, NR1 occurred in all bulbospinal tyrosine hydroxylase-positive neurons and 96% of bulbospinal tyrosine hydroxylase-negative neurons, which were more common in sections containing the facial nucleus. In raphé pallidus, the parapyramidal region and the marginal layer, 98% of bulbospinal tryptophan hydroxylase-positive neurons contained NR1-immunoreactivity. NR1 was also present in all of the bulbospinal tryptophan hydroxylase-negative neurons, which comprised 20% of bulbospinal neurons in raphé pallidus and the parapyramidal region. These results show that virtually all bulbospinal tyrosine hydroxylase and non-tyrosine hydroxylase neurons in the rostral ventrolateral medulla and virtually all bulbospinal serotonin and non-serotonin neurons in raphé pallidus and the parapyramidal region express NR1, the obligatory subunit of the NMDA receptor. NMDA receptors on bulbospinal neurons in the rostral ventral medulla likely influence sympathoexcitation in normal and pathological conditions.

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Section: Bulbospinal Catecholamine Neurons In the Rostral Ventral Medsupporting

confidence: 74%

Immunoreactivity for the NMDA NR1 subunit in bulbospinal catecholamine and serotonin neurons of rat ventral medulla

Llewellyn‐Smith¹,

Mueller²

2013

Autonomic Neuroscience

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“…Indeed, greater blood pressure or sympathoexcitatory responses to microinjections of glutamate in the RVLM have been observed in sedentary compared to physically active animals (Martins-Pinge et al, 2005; Mueller, 2007; Mischel and Mueller, 2011). The fact that responses to other excitatory neurotransmitters, such as angiotensin II, are not enhanced in sedentary animals (Becker et al, 2005) suggests that alterations in excitatory neurotransmission may be more specific to glutamatergic mechanisms; however, this remains to be fully established.…”

Section: Discussionmentioning

confidence: 99%

Selective enhancement of glutamate-mediated pressor responses after GABAA receptor blockade in the RVLM of sedentary versus spontaneous wheel running rats

Mueller¹,

Mischel²

2012

Front. Physio.

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Overactivity of the sympathetic nervous system (SNS) is a hallmark of many cardiovascular diseases. It is also well-known that physical inactivity independently contributes to cardiovascular diseases, likely in part via increased SNS activity. Recent work from our laboratory has demonstrated increased SNS responses in sedentary animals following either direct activation or disinhibition of the rostral ventrolateral medulla (RVLM), an integral cardiovascular brainstem region. These data led us to hypothesize that the interaction between excitation and inhibition of the RVLM is altered in sedentary versus physically active animals. To test this hypothesis, we recorded mean arterial pressure (MAP) and lumbar sympathetic nerve activity (LSNA) in Inactin anesthetized rats that were housed for 8–12 weeks with or without access to a running wheel. Pressor responses to direct activation of the RVLM with glutamate were similar between groups under intact conditions. However, blockade of γ-aminobutyric acid (GABA)A receptors with bicuculline selectively enhanced pressor responses to glutamate in sedentary animals. Interestingly, LSNA responses to glutamate were not enhanced in sedentary versus active animals in the presence or absence of tonic GABAergic tone. These results suggest that sedentary compared to active conditions enhance GABAergic inhibition of glutamate-sensitive neurons in the RVLM that are involved in blood pressure regulation, and by mechanisms that do not involve LSNA. We also speculate that regular physical activity has differential effects on SNS activity to specific vascular beds and may reduce the risk of developing cardiovascular diseases via changes occurring in the RVLM.

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“…2,[11][12][13] Again, no change in HR after relaxation technique in healthy volunteers after practicing yoga for 3-15 years was also reported 14 .Sedentary lifestyle has been found to be associated with decrement of cardiac parasympathetic activity. [13][14][15][16] In Bangladesh, the effect of sedentary life style on cardiac autonomic nerve function was investigated by comparing HRV between sedentary adolescents and adolescent athlets and also between adult heavy workers and adult sedentary people. 13,-15,17 But the effect of relaxation technique on HRV in sedentary subjects was not investigated.…”

Section: Articlementioning

confidence: 99%

Effect of Deep Relaxation on Heart Rate Variability in Sedentary Females

E-Fatema¹,

Begum

Ferdousi

2014

J Bangladesh Soc Physiol

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Background: Sedentary lifestyle is associated with low heart rate variability (HRV). Deep Relaxation Technique (DRT) increase HRV which reduces the risk of coronary heart diseases. Objectives: To assess HRV after practicing DRT to find out it's effect on cardiac autonomic nerve function in sedentary subjects. Methods: This cross sectional study was carried out in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University between July 2012 and June 2013 on 30 apparently healthy sedentary females aged 25-35 years (study) who were practicing DRT with 3 months duration. For comparison, age and BMI matched 30 apparently healthy sedentary females who had no experience of relaxation technique (control) were also studied. Both groups were selected from the sedentary housewives by personal contact. The study subjects were the participants in a private yoga center in Dhaka. HRV was assessed by a Polygraph. Statistical analysis was done by Independent Sample ttest. Results: Resting mean heart rate (p<0.001) was significantly lower and mean R-R interval and SDNN (p<0.001), RMSSD (p<0.05) were significantly higher in the relaxation group than the control group. Conclusion: DRT improves cardiac autonomic nerve function with parasympathetic dominance in sedentary females.

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(In)activity-dependent alterations in resting and reflex control of splanchnic sympathetic nerve activity

Cited by 40 publications

References 70 publications

Immunoreactivity for the NMDA NR1 subunit in bulbospinal catecholamine and serotonin neurons of rat ventral medulla

Immunoreactivity for the NMDA NR1 subunit in bulbospinal catecholamine and serotonin neurons of rat ventral medulla

Selective enhancement of glutamate-mediated pressor responses after GABAA receptor blockade in the RVLM of sedentary versus spontaneous wheel running rats

Effect of Deep Relaxation on Heart Rate Variability in Sedentary Females

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