Stress enhances muscle nociceptor activity in the rat

Abstract

Chronic widespread pain, such as observed in irritable bowel (IBS) and fibromyalgia (FMS) syndrome, are markedly affected by stress. While such forms of stress-induced hyperalgesia are generally considered manifestations of ‘central sensitization’, recent studies in patients with IBS and FMS suggest an additional, peripheral contribution. To examine the effect of stress on muscle nociceptor function, we evaluated activity in nociceptors innervating the gastrocnemius muscle in an animal model of chronic widespread pain, water avoidance stress, in the rat. This stressor, which produces mechanical hyperalgesia in skeletal muscle produced a significant decrease (~34%) in mechanical threshold of muscle nociceptors and a marked, ~2-fold increase in the number of action potentials produced by a prolonged (60 s) fixed intensity suprathreshold 10 g stimulus. Stress also induced an increase in conduction velocity from 1.25 m/s to 2.09 m/s, and increased variability in neuronal activity. Given that these changes, each of at least moderate magnitude, would be expected to enhance nociceptor activity, it is likely that, taken together, they contribute to the enhanced nociception observed in this model of stress-induced chronic widespread pain.

Short-Term Sleep Disturbance–Induced Stress Does not Affect Basal Pain Perception, but Does Delay Postsurgical Pain Recovery

“…18,47 Animals subjected to sleep disturbance 1 h daily for 10 consecutive days displayed mechanical and visceral hyperalgesia. 10,17,29 Consistently, the present study showed that REMSD 6 h daily for 4–5 consecutive days led to mechanical, thermal, and cold pain hypersensitivities in normal rats. These preclinical studies may mimic clinical observations, in which some patients with severe physical or psychological stress frequently report pain and exacerbated existing pain associated with chronic pain disorders.…”

Role for monocyte chemoattractant protein-1 in the induction of chronic muscle pain in the rat

“…Water-avoidance induced stress, which produces mechanical hyperalgesia, is considered a model of widespread muscle pain [29] is associated with increased firing in nociceptors innervating the gastrocnemius muscle [23]. To induce water avoidance stress, rats were placed on a 10 cm high acrylic platform (8 × 8 cm) in the center of a clear plastic tank (45 cm length × 25 cm width × 25 cm height) filled with room temperature tap water to a depth of 9 cm, for 1 h/day, for 10 consecutive days.…”

Genotype-dependent responsivity to inflammatory pain: A role for TRPV1 in the periaqueductal grey

“…Visceral hyperalgesia (Bradesi et al, 2009(Bradesi et al, , 2007(Bradesi et al, , 2006He et al, 2013;Larauche et al, 2008 (Chen et al, 2011;Green et al, 2011b) Chapter 1…”