Effects of administration of α₂ adrenergic receptor agonist into psoas major muscle on inflammatory pain induced by injection of complete Freund’s adjuvant in rats

Abstract

α2 adrenergic agonists are widely used in clinical anesthesia and ICU sedation owing to their effective sedative and analgesic effects. Lumbago and leg pain is the most common clinical pain disease. Studies have reported that lumbago and leg pain is associated with dysregulation of paravertebral muscles, especially psoas major muscles. In the present study, a unilateral lower extremity chronic inflammation and pain model was established by subcutaneous administration of low-dose complete Fredrin's adjuvant (CFA) into the posterior paw of rats. α2 adrenalin receptor agonist was then injected into the psoas major muscle. Behavioral tests were conducted for 21 days. Psoas major muscle tissue was harvested for evaluation of biochemical indexes related to pain. The effect of α2 adrenergic receptor agonist injected into psoas major muscle on chronic inflammatory pain of lower extremities in rats was explored. The results showed that injection of α2 adrenergic receptor agonist into the psoas major muscle relieved CFA-induced mechanical hyperalgesia. Administration of α2 adrenergic receptor antagonist yohimbine reversed the analgesic effect of α2 adrenergic receptor agonists. Administration of dexmedetomidine into psoas major muscle downregulated the levels of norepinephrine, interleukin-6 and tumor necrosis factor-α in tissues. The findings of the present study show that administration of α2 adrenoceptor agonists into the psoas major muscle relieves chronic inflammatory pain induced by CFA. Local injection of dexmedetomidine also exerted anti-inflammatory and anti-sympathetic effect by activating α2-adrenoceptor in the psoas major muscle.

Regulation of nociception threshold by norepinephrine through adrenergic α2 receptor in rat models of Parkinson's disease

“…In one study, preinjection of clonidine into the hind paw of rats reduced the sensitivity of the sole to thermal stimulation, 28 it may be that norepinephrine inhibits capsaicin‐induced transient receptor potential vanillin 1 (TRPV1) activity via α2 receptor in rat dorsal root ganglion (DRG) neurons. Mechanical hyperalgesia induced by Fredlin adjuvant (CFA) can be relieved by injection of α2 adrenergic receptor agonists into the psoas major muscle 29 . Therefore, it is considered that the improvement of algesthesia induced by guanfacine in this study may be achieved through the effect of peripheral adrenergic α2 receptor.…”

“…Mechanical hyperalgesia induced by Fredlin adjuvant (CFA) can be relieved by injection of α2 adrenergic receptor agonists into the psoas major muscle. 29 Therefore, it is considered that the improvement of algesthesia induced by guanfacine in this study may be achieved through the effect of peripheral adrenergic α2 receptor. The use of guanfacine was also associated with a decrease in GFAP‐positive cells in the prefrontal lobe and cingulate gyrus, just as activation of microglial cells in the spinal cord after peripheral nerve injury may make pain persist.…”

Effect of esketamine combined with dexmedetomidine on delirium in sedation for mechanically ventilated ICU patients: protocol for a nested substudy within a randomized controlled trial

“…Esketamine mainly exerts analgesic effects by blocking NMDA receptors and also relieves opioid-induced hyperalgesia [ 32 ]. Dexmedetomidine excites α 2 adrenergic receptors to inhibit the release of excitatory neurotransmitters and hyperpolarize cells, thereby inhibiting pain signaling [ 33 ]. Both can reduce the use of opioid analgesia through eliciting multimodal analgesia.…”

Effect of Dexmedetomidine Added to Lidocaine Cartridge on the Level of Patient Sedation, Cooperation, and Patient and Surgeon Satisfaction during Mandibular Third-Molar Extraction Surgery: A Randomized Double-Blind Controlled Trial

“…It is also associated with reduced blood pressure and heart rate [ 16 ]. DEX also has vasoconstrictor features by acting on alpha-2 β receptors of peripheral blood vessels and has been shown to enhance the anesthetic effects and prolong the duration of action of LIDO ( Table 1 ) local anesthesia as well as reduce the required dosage of anesthetic drugs [ 17 ]. Therefore, it is suggested that DEX can be helpful for anxiety control in patients undergoing dental surgery when achieving adequate patient cooperation is a challenging issue for the operator [ 18 ].…”