Differential responses of neurons in the rat caudal ventrolateral medulla to visceral and somatic noxious stimuli and their alterations in colitis

Lyubashina, O. A.; Sivachenko, Ivan B.; Sokolov, Alexey Y.

doi:10.1016/j.brainresbull.2019.07.030

Cited by 13 publications

(6 citation statements)

References 84 publications

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“…The observed opposite effect of visceral and somatic noxious inputs on cortical vasculature can be mediated by several potential mechanisms. For instance, previous studies, including our, have revealed that visceral and somatic pain stimuli produce different patterns of neuronal activity in the caudal ventrolateral medulla (Lyubashina et al, 2019), nucleus of the solitary tract, locus coeruleus (Han et al, 2003), and raphe nucleus (Brink and Mason, 2003). On the one hand, prevailing difference between visceral and somatic pain-induced alterations in systemic ABP (and in concomitant opposite changes in CBF) can be caused by diverse activation of these brainstem areas.…”

Section: Discussionmentioning

confidence: 99%

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Contactless Assessment of Cerebral Autoregulation by Photoplethysmographic Imaging at Green Illumination

et al. 2019

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Accurate and practical assessment of the brain circulation is needed to adequately estimate the viability of cerebral blood flow regulatory mechanisms in various physiological conditions. The objective of our study was to examine feasibility of the contactless green-light imaging photoplethysmography (PPG) for assessing cerebral autoregulation by revealing the dynamic relationships between cortical microcirculation assessed by PPG and changes in systemic blood pressure caused by visceral and somatic peripheral stimuli. In anesthetized male Wistar rats, the PPG video images of the open parietal cortex (either with unimpaired or dissected dura mater), electrocardiogram, and systemic arterial blood pressure (ABP) in the femoral artery were continuously recorded before, during and after visceral (colorectal distension) or somatic (tail squeezing) stimulation. In the vast majority of experiments with intact and removed dura mater, both spontaneous and peripheral stimulation-evoked changes in ABP negatively correlated with the accompanying alterations in the amplitude of pulsatile PPG component (APC), i.e., an increase of ABP resulted in a decrease of APC and vice versa. The most pronounced ABP and APC alterations were induced by noxious stimuli. Visceral painful stimulation in all cases caused short-term hypotension with simultaneous increase in cortical APC, whereas somatic noxious stimuli in 8 of 21 trials produced hypertensive effect with decreased APC. Animals with pressure 50-70 mmHg possessed higher negative cerebrovascular response rate of ABP-APC gradients than rats with either lower or higher pressure. Severe hypotension reversed the negative ratio to positive one, which was especially evident under visceral pain stimulation. Amplitude of the pulsatile PPG component probably reflects the regulation of vascular tone of cerebral cortex in response to systemic blood pressure fluctuations. When combined with different kinds of peripheral stimuli, the technique is capable for evaluation of normal and elucidation of impaired cerebrovascular system reactivity to particular physiological events, for example pain. The reported contactless PPG monitoring of cortical circulatory dynamics during neurosurgical interventions in combination with recordings of changes in other physiological parameters, such as systemic blood pressure and ECG, has the appealing potential to monitor viability of the cortex vessels and determine the state of patient’s cerebrovascular autoregulation.

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Section: Discussionmentioning

confidence: 99%

“…Innocuous (tactile) somatic stimulation was delivered to the rat’s tail with forceps. Somatic nociception was caused by firmly squeezing the base of the tail by surgical forceps with a fixed lock mechanism as it was described previously (Lyubashina et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

Contactless Assessment of Cerebral Autoregulation by Photoplethysmographic Imaging at Green Illumination

et al. 2019

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“…Interestingly, in our experiments in healthy control rats alongside with the attenuation of the CRD‐evoked neuronal excitation the facilitatory action of buspirone on the CVLM neuron inhibitory responses to noxious CRD was revealed. The apparent resemblance of the CRD‐inhibited CVLM neurons to the OFF cells defined in the rostral ventromedial medulla (Fields, 2004; Fields et al, 1983; Martins & Tavares, 2017) allowed us and other authors to suggest a functional alliance between these neuronal populations, promoting antinociception (Lyubashina et al, 2016, 2018, 2019; Pinto‐Ribeiro et al, 2011). Considering this, the revealed buspirone‐induced enhancement of the abdominal nociception‐related inhibitory events within the CVLM may at least partially contribute to the antinociceptive effect of the 5‐HT1A agonist in normal conditions.…”

Section: Discussionmentioning

confidence: 88%

“…The rats were divided following simple randomization into two groups as healthy control (n = 45) and post-colitis ones (n = 44). In the last group, animals were fasting, but not deprived of water, for 16 h and then colonic inflammation was induced as previously described (Lyubashina et al, 2018(Lyubashina et al, , 2019. In brief, during a short period of anesthesia with isoflurane, 20 mg of trinitrobenzenesulfonic acid (TNBS, Sigma-Aldrich, St. Louis, MO, USA) in 0.25 mL of 50% ethanol was slowly administered into the lumen of the descending colon through an 8-cm polyethylene catheter (1.3 mm in outer diameter) inserted via the anus.…”

Section: Induction Of Colitismentioning

confidence: 99%

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Opposing effects of 5‐HT1A receptor agonist buspirone on supraspinal abdominal pain transmission in normal and visceral hypersensitive rats

Lyubashina,

Sivachenko,

Sushkevich

et al. 2023

J of Neuroscience Research

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The serotonergic 5‐HT1A receptors are implicated in the central mechanisms of visceral pain, but their role in these processes is controversial. Considering existing evidences for organic inflammation‐triggered neuroplastic changes in the brain serotonergic circuitry, the ambiguous contribution of 5‐HT1A receptors to supraspinal control of visceral pain in normal and post‐inflammatory conditions can be assumed. In this study performed on male Wistar rats, we used microelectrode recording of the caudal ventrolateral medulla (CVLM) neuron responses to colorectal distension (CRD) and electromyography recording of CRD‐evoked visceromotor reactions (VMRs) to evaluate post‐colitis changes in the effects of 5‐HT1A agonist buspirone on supraspinal visceral nociceptive transmission. In rats recovered from trinitrobenzene sulfonic acid colitis, the CRD‐induced CVLM neuronal excitation and VMRs were increased compared with those in healthy animals, revealing post‐inflammatory intestinal hypersensitivity. Intravenous buspirone (2 and 4 mg/kg) under urethane anesthesia dose‐dependently suppressed CVLM excitatory neuron responses to noxious CRD in healthy rats, but caused dose‐independent increase in the already enhanced nociceptive activation of CVLM neurons in post‐colitis animals, losing also its normally occurring faciliatory effect on CRD‐evoked inhibitory medullary neurotransmission and suppressive action on hemodynamic reactions to CRD. In line with this, subcutaneous injection of buspirone (2 mg/kg) in conscious rats, which attenuated CRD‐induced VMRs in controls, further increased VMRs in hypersensitive animals. The data obtained indicate a shift from anti‐ to pronociceptive contribution of 5‐HT1A‐dependent mechanisms to supraspinal transmission of visceral nociception in intestinal hypersensitivity conditions, arguing for the disutility of buspirone and possibly other 5‐HT1A agonists for relieving post‐inflammatory abdominal pain.

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Translating Colonic Sensory Afferent Peripheral Mechanosensitivity into the Spinal Cord Dorsal Horn

Harrington

2023

Visceral Pain

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Differential responses of neurons in the rat caudal ventrolateral medulla to visceral and somatic noxious stimuli and their alterations in colitis

Cited by 13 publications

References 84 publications

Contactless Assessment of Cerebral Autoregulation by Photoplethysmographic Imaging at Green Illumination

Contactless Assessment of Cerebral Autoregulation by Photoplethysmographic Imaging at Green Illumination

Opposing effects of 5‐HT1A receptor agonist buspirone on supraspinal abdominal pain transmission in normal and visceral hypersensitive rats

Translating Colonic Sensory Afferent Peripheral Mechanosensitivity into the Spinal Cord Dorsal Horn

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