Adenosine triphosphate mediates the pain tolerance effect of manual acupuncture at Zusanli (ST36) in mice.

OBJECTIVE: To investigate the mechanisms behind the effects of acupuncture in Traditional Chinese Medicine, we delved into the adenosine triphosphate/peripheral purinergic P2X receptor 3 (ATP/P2X3) receptor signaling system as an indicator of the body's energy state, commonly referred to as "Qi". METHODS: The tail-flick test was utilized to explore the impact of acupuncture on pain tolerance threshold (PTT) in mice, while also assessing adenosine (ADO) levels and adenylate energy charge (EC) at Zusanli (ST36). The study further investigated the dose-dependent effects of acupuncture on PTT and ADO levels at Zusanli (ST36). To shed light on the underlying mechanisms of acupuncture's effects, the study examined the impact of ATP, a P2X3 receptor antagonist, and adenosine disodium on PTT following acupuncture administration. RESULTS: Acupuncture at Zusanli (ST36) led to significant improvements in PTT in mice, with the most effective interventions being twirling for 2 min and needle retention for 28 min. These interventions also resulted in significant increases in ATP levels. The effects of acupuncture were further augmented by administration of different doses of ATP at Zusanli (ST36), and pretreatment with a P2X3 receptor antagonist decreased PTT. Adenylate EC peaked at 30 min after intraperitoneal injection of ATP, and pretreatment with various doses of i.p. ATP 30 min prior to acupuncture increased PTT in a dose-dependent manner. Additionally, pretreatment with an i.p. or intramuscular injection of adenosine disodium enhanced the effects of acupuncture. CONCLUSION: This research provides compelling evidence that ATP is involved in the regulation of PTT through acupuncture, revealing new avenues for achieving enhanced clinical outcomes.

Effect of lappaconitine on neuropathic pain mediated by retrograde transport of P2X3 receptor in dorsal root ganglion neurons of rats with chronic constriction injury of the sciatic nerve / 中华创伤杂志

Objective:To investigate the effect of lappaconitine (LA) on neuropathic pain (NPP) mediated by retrograde transport of purinergic P2X3 receptor (P2X3R) in dorsal root ganglion (DRG) neurons of rats with chronic constriction injury (CCI) of the sciatic nerve.Methods:Seventy-two male healthy SD rats were selected to construct the NPP model following CCI of the sciatic nerve by ligating the right sciatic nerve. according to the random number table method. The rats were divided into CCI group, CCI+LA group and normal control group according to the random number table method, with 24 rats in each group. In normal control group, the right sciatic nerve was exposed without ligation. In CCI+LA group, the rats were given 2 g/L LA (ie, 4 mg/kg intravenously for once a day for one day only) after the same treatment as CCI group. Other two groups were injected with the identical amount of normal saline in the same way. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were evaluated before injury and at 2, 6, 12 and 24 hours after injury to evaluate the symptoms of neuralgia caused by nerve injury. The proximal and distal nerve fragments were collected in the three groups at 2, 6, 12 and 24 hours after injury. Western blotting was applied to analyze the expression of P2X3R at 2, 6, 12 and 24 hours after injury and the expression of neurotrophic factor (NGF) and tyrosine kinase receptor A (TrkA) at 24 hours after injury to evaluate the effect of LA on P2X3R, NGF and TrkA.Results:There were insignificant differences in MWT and TWL among all groups before injury (all P>0.05). Compared with normal control group, MWT and TWL were significantly decreased in CCI group and CCI+LA group at 2, 6, 12 and 24 hours after injury (all P<0.05 or 0.01). There were insignificant differences in MWT and TWL between CCI group and CCI+LA group at 2 and 6 hours after injury (all P>0.05), while MWT and TWL were significantly higher in CCI+LA group than those in CCI group at 12 and 24 hours after injury (all P<0.05 or 0.01). In the proximal sciatic nerve segment, Western blotting showed similar levels of P2X3R among all groups at 2, 6, 12 and 24 hours after injury (all P>0.05). In the distal sciatic nerve segment, Western blotting showed higher expression of P2X3R in CCI group than that in normal control group at 2, 6, 12, 24 hours after injury (all P<0.01), higher expression of P2X3R in CCI+LA group than that in normal control group at 2, 6 and 12 hours after injury (all P<0.05), similar expression of P2X3R expression between CCI+LA group and normal control group at 24 hours after injury ( P>0.05), similar expression of P2X3R between CCI group and CCI+LA group at 2 and 6 hours after injury (all P>0.05), and lower expression of P2X3R in CCI+LA group than that in CCI group at 12 and 24 hours after injury ( P<0.05 or 0.01). In the proximal and distal nerve fragments, the expression of NGF was lower in normal control group than that in CCI group and CCI+LA group ( P<0.05 or 0.01), but was similar between CCI group and CCI+LA group at 24 hours after injury ( P>0.05). In the proximal and distal nerve fragments, there were insignificant differences in the expression of TrkA among all groups at 24 hours after injury (all P>0.05). Conclusion:Early LA treatment after injury can alleviate mechanical and thermal hyperalgesia in NPP rats, which may be related to the reduction of P2X3R retrograde transport in DRG neuron axonal.

Voiding Dysfunction in Old Male Rats Associated With Enlarged Prostate and Irregular Afferent-Triggered Reflex Responses.

PURPOSE: This study was conducted to evaluate the hypothesis that an enlarged prostate in old rats may lead to complications associated with voiding dysfunction involving ionotropic P2X2/3-type purinergic receptors. METHODS: Intact animals were divided into male young (MYR; 8-10 weeks old) and male old (MOR; 20 months old) rats. The animals underwent simultaneous detrusor electromyography (EMG) and suprapubic cystometry (CMG) under urethane anesthesia. Immunofluorescence techniques were used to evaluate prostatic autonomic innervation and P2X3R expression in bladder urothelial cells. The functional role of P2X3R was characterized by intramuscular application of AF-353, a selective P2X2/3R antagonist. RESULTS: The prostate index significantly increased in MOR, suggestive of an enlarged prostate affecting micturition patterns. Significant EMG and CMG differences were found between MYR and MOR. Higher immunoreactivity for P2X2/3R in the urothelial layer and for prostatic neurofilaments was seen in MOR. Systemic inhibition of P2X2/3R had minimal effects on MYR responsiveness, but improved voiding function in MOR with a marked decrease of intravesical pressure and bladder contractile responses. CONCLUSION: The data support the hypothesis that an enlarged prostate in MOR may contribute to voiding dysfunction involving activation of P2X2/3R, which enhances a prostate-bladder reflex. This reflex may increase bladder afferent transmission and activation of increased prostate innervation, leading to voiding dysfunction.