Inflammation in dorsal root ganglia after peripheral nerve injury: Effects of the sympathetic innervation

Following a peripheral nerve injury, a sterile inflammation develops in sympathetic and dorsal root ganglia (DRGs) with axons that project in the damaged nerve trunk. Macrophages and T-lymphocytes invade these gan- glia where they are believed to release cytokines that lead to hyperexcitability and ectopic discharge, possibly contributing to neuropathic pain. Here, we examined the role of the sympathetic innervation in the inflammation of L5 DRGs of Wistar rats following transection of the sciatic nerve, comparing the effects of specific surgical in- terventions 10–14 days prior to the nerve lesion with those of chronic administration of adrenoceptor antago- nists. Immunohistochemistry was used to define the invading immune cell populations 7 days after sciatic transection. Removal of sympathetic activity in the hind limb by transecting the preganglionic input to the rele- vant lumbar sympathetic ganglia (ipsi- or bilateral decentralization) or by ipsilateral removal of these ganglia with degeneration of postganglionic axons (denervation), caused less DRG inflammation than occurred after a sham sympathectomy. By contrast, denervation of the lymph node draining the lesion site potentiated T-cell in- flux. Systemic treatment with antagonists of α1-adrenoceptors (prazosin) or β-adrenoceptors (propranolol) led to opposite but unexpected effects on infiltration of DRGs after sciatic transection. Prazosin potentiated the influx of macrophages and CD4+ T-lymphocytes whereas propranolol tended to reduce immune cell invasion. These data are hard to reconcile with many in vitro studies in which catecholamines acting mainly via β2-adrenoceptors have inhibited the activation and proliferation of immune cells following an inflamma- tory challenge. 

Autonomic Neuroscience: Basic and Clinical 182 (2014) 108–117 

Neuroscience Research Australia, Randwick, NSW 2031, and the University of New South Wales, Sydney, NSW 2052, Australia

In the setting of sympathectomy, interference with any of the effectors evokes immediate, precipitous declines in blood pressure

"From the finding that removal of the sympathetic nerves did not affect blood pressure much, Cannon inferred that the sympathetic nervous system did not contribute to blood pressure in intact, undisturbed organism. In the 1980s, however, several reports showed  that sympathectomy compensatorily activates other effectors, such as the renin-angiotensin-aldosterone system, the vasopressin system, and the adrenal medulla, and compensatory activation of these effectors maintains blood pressure at approximately normal levels. In the setting of sympathectomy, interference with any of the effectors evokes immediate, precipitous declines in blood pressure. Because Cannon was so firmly convinced of the functional unity of the sympathoadrenal system, which would be activated only in emergencies, he never considered adequately the possibility that the sympathetic nervous system might indeed contribute to levels of blood pressure and other monitored variables under resting conditions." Adrenaline and the Inner World:  An Introduction to Scientific Integrative Medicine

David S. Goldstein

JHU Press, 01/04/2008 - Medical - 328 pages

"patient information must include the long-term substantial risk for severe CS and regret of the procedure"

http://www.ncbi.nlm.nih.gov/pubmed/22191130

lowering of heart rate and blood pressure, decreased responsiveness of the cardiocirculatory system to emotional stimuli after sympathectomy

"lowering of heart rate and blood pressure, decreased responsiveness of the cardiocirculatory system to emotional stimuli: it is an effect that is especially noticeable in patients operated on for erythrophobia and less evident in those operated for hyperhidrosis. It is almost always a welcome phenomenon, which contributes considerably to the feeling of tranquility and serenity that generally supersedes anxiety. Excessive reduction in blood pressure or heart rate may lead to a state of weakness and fatigue that may require removal of the clips in approx. 2%. This rare state of asthenia contrasts with the increased energy and vigor that most patients experience when they feel freed from overwhelming anxiety."    

"The neurovegetative nervous system is, however, very dynamic and tends to adapt continuously during lifetime to all environmental or organic changes and conditions. Therefore, it reacts very individually when a reflex circuit has been blocked. The resulting side effects cannot be predicted in detail, and though they in most patients are relatively mild or even absent, there is a small group of patients developing heavy side effects. Therefore, surgery should only be considered in carefully selected cases in whom non-invasive treatment has failed and in whom the detrimental consequences of erythrophobia regarding the psychosocial situation and the quality of life is such to justify more adverse side effects. It should also always be kept in mind that therapy can be ineffective and that, in the long term, 10-15% of patients do not consider themselves satisfied with the result of surgery. In any case, the author prefers the use of a potentially reversible surgical technique (ESB), instead of destructive techniques (cutting, coagulation, removal of ganglia)."  

http://www.chir.it/en_erythrophobia.php

significant associations between heart rate and regional cerebral blood flow

Neurosci Biobehav Rev. 2012 Feb;36(2):747-56. doi: 10.1016/j.neubiorev.2011.11.009. Epub 2011 Dec 8.

A meta-analysis of heart rate variability and neuroimaging studies: implications for heart rate variability as a marker of stress and health.

The intimate connection between the brain and the heart was enunciated by Claude Bernard over 150 years ago. In our neurovisceral integration model we have tried to build on this pioneering work. In the present paper we further elaborate our model and update it with recent results. Specifically, we performed a meta-analysis of recent neuroimaging studies on the relationship between heart rate variability and regional cerebral blood flow. We identified a number of regions, including the amygdala and ventromedial prefrontal cortex, in which significant associations across studies were found. We further propose that the default response to uncertainty is the threat response and may be related to the well known negativity bias. Heart rate variability may provide an index of how strongly 'top-down' appraisals, mediated by cortical-subcortical pathways, shape brainstem activity and autonomic responses in the body. If the default response to uncertainty is the threat response, as we propose here, contextual information represented in 'appraisal' systems may be necessary to overcome this bias during daily life. Thus, HRV may serve as a proxy for 'vertical integration' of the brain mechanisms that guide flexible control over behavior with peripheral physiology, and as such provides an important window into understanding stress and health.

http://www.ncbi.nlm.nih.gov/pubmed/22178086