The pathophysiology of visceral pain in patients with irritable bowel syndrome remains largely unknown. Our previous study showed that neonatal maternal deprivation (NMD) does not induce visceral hypersensitivity at the age of 6 weeks in rats. The aim of this study was to determine whether NMD followed by adult stress at the age of 6 weeks induces visceral pain in rats and to investigate the roles of adrenergic signaling in visceral pain. Here we showed that NMD rats exhibited visceral hypersensitivity 6 h and 24 h after the termination of adult multiple stressors (AMSs). The plasma level of norepinephrine was significantly increased in NMD rats after AMSs. Whole-cell patch-clamp recording showed that the excitability of dorsal root ganglion (DRG) neurons from NMD rats with AMSs was remarkably increased. The expression of β adrenergic receptors at the protein and mRNA levels was markedly higher in NMD rats with AMSs than in rats with NMD alone. Inhibition of β adrenergic receptors with propranolol or butoxamine enhanced the colorectal distention threshold and application of butoxamine also reversed the enhanced hypersensitivity of DRG neurons. Overall, our data demonstrate that AMS induces visceral hypersensitivity in NMD rats, in part due to enhanced NE-β adrenergic signaling in DRGs.
Adrenergic Agents ; pharmacology ; Animals ; Ganglia, Spinal ; drug effects ; Hyperalgesia ; drug therapy ; physiopathology ; Hypersensitivity ; drug therapy ; Male ; Maternal Deprivation ; Neurons ; drug effects ; Patch-Clamp Techniques ; methods ; Rats, Sprague-Dawley ; Signal Transduction ; drug effects ; Stress, Physiological ; physiology ; Visceral Pain ; chemically induced ; metabolism

Cognition and pain share common neural substrates and interact reciprocally: chronic pain compromises cognitive performance, whereas cognitive processes modulate pain perception. In the present study, we established a non-drug-dependent rat model of context-based analgesia, where two different contexts (dark and bright) were matched with a high (52°C) or low (48°C) temperature in the hot-plate test during training. Before and after training, we set the temperature to the high level in both contexts. Rats showed longer paw licking latencies in trials with the context originally matched to a low temperature than those to a high temperature, indicating successful establishment of a context-based analgesic effect in rats. This effect was blocked by intraperitoneal injection of naloxone (an opioid receptor antagonist) before the probe. The context-based analgesic effect also disappeared after optogenetic activation or inhibition of the bilateral infralimbic or prelimbic sub-region of the prefrontal cortex. In brief, we established a context-based, non-drug dependent, placebo-like analgesia model in the rat. This model provides a new and useful tool for investigating the cognitive modulation of pain.
Action Potentials ; drug effects ; physiology ; Analgesics ; pharmacology ; therapeutic use ; Animals ; Disease Models, Animal ; Electric Stimulation ; Female ; In Vitro Techniques ; Naloxone ; pharmacology ; Narcotic Antagonists ; pharmacology ; Optogenetics ; Pain ; drug therapy ; pathology ; physiopathology ; Pain Measurement ; drug effects ; Pain Threshold ; drug effects ; physiology ; Patch-Clamp Techniques ; Physical Stimulation ; Prefrontal Cortex ; drug effects ; metabolism ; pathology ; Pyramidal Cells ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley ; Time Factors

Adult ; Atherosclerosis ; diagnosis ; Chest Pain ; Coronary Aneurysm ; diagnosis ; Coronary Angiography ; Coronary Artery Disease ; diagnostic imaging ; Coronary Vessel Anomalies ; diagnosis ; Coronary Vessels ; diagnostic imaging ; physiopathology ; Electrocardiography ; Humans ; Male ; Risk Factors ; Troponin I ; metabolism ; Vascular Diseases ; congenital ; diagnosis

The pain peptide adrenomedullin (AM) plays a pivotal role in pathological pain. The present study was designed to investigate the effect of blockade of AM receptor on bone cancer pain (BCP) and its mechanism. BCP was developed by inoculation of Walker 256 mammary gland carcinoma cells in the tibia medullary cavity of Sprague Dawley rats. The selective AM receptor antagonist AMwas administered intrathecally on 15 d after the inoculation. Quantitative real-time PCR was used to detect mRNA level of CC chemokine ligand 2 (CCL2) in dorsal root ganglion (DRG). Double immunofluorescence staining was used to analyze the localizations of CCL2 and AM in DRG of normal rats. The results showed that, from 6 to15 d after the inoculation, the animals showed significant reduction in the mechanical pain threshold in the ipsilateral hindpaw, companied by the decline in bone density of tibia bone. The expression of CCL2 mRNA in DRG of BCP rats was increased by 3 folds (P < 0.001 vs saline group). Intrathecal administration of AMabolished bone cancer-induced mechanical allodynia and increase of CCL2 mRNA level (P < 0.001). In normal rats, CCL2 was co-localized with AM in DRG neurons. These results suggest that AM may play a role in the pathogenesis of BCP. The increased AM bioactivity up-regulates CCL2 expression in DRG, which may contribute to the induction of pain hypersensitivity in bone cancer.
Adrenomedullin ; administration & dosage ; pharmacology ; Animals ; Bone Neoplasms ; drug therapy ; Chemokine CCL2 ; metabolism ; Ganglia, Spinal ; physiopathology ; Hyperalgesia ; drug therapy ; Pain ; drug therapy ; Pain Threshold ; Peptide Fragments ; administration & dosage ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction ; Receptors, Adrenomedullin ; antagonists & inhibitors

PURPOSE: The pathophysiology of discogenic low back pain is not fully understood. Tetrodotoxin-sensitive voltage-gated sodium (NaV) channels are associated with primary sensory nerve transmission, and the NaV1.7 channel has emerged as an analgesic target. Previously, we found increased NaV1.7 expression in dorsal root ganglion (DRG) neurons innervating injured discs. This study aimed to examine the effect of blocking NaV1.7 on sensory nerves after disc injury. MATERIALS AND METHODS: Rat DRG neurons innervating the L5/6 disc were labeled with Fluoro-Gold (FG) neurotracer. Twenty-four rats underwent intervertebral disc puncture (puncture group) and 12 rats underwent sham surgery (non-puncture group). The injury group was divided into a saline infusion group (puncture+saline group) and a NaV1.7 inhibition group, injected with anti-NaV1.7 antibody (puncture+anti-NaV1.7 group); n=12 per group. Seven and 14 days post-surgery, L1 to L6 DRGs were harvested and immunostained for calcitonin gene-related peptide (CGRP) (an inflammatory pain marker), and the proportion of CGRP-immunoreactive (IR) DRG neurons of all FG-positive neurons was evaluated. RESULTS: The ratio of CGRP-IR DRG neurons to total FG-labeled neurons in the puncture+saline group significantly increased at 7 and 14 days, compared with the non-puncture group, respectively (p<0.05). Application of anti-NaV1.7 into the disc significantly decreased the ratio of CGRP-IR DRG neurons to total FG-labeled neurons after disc puncture at 7 and 14 days (40% and 37%, respectively; p<0.05). CONCLUSION: NaV1.7 antibody suppressed CGRP expression in disc DRG neurons. Anti-NaV1.7 antibody is a potential therapeutic target for pain control in patients with lumbar disc degeneration.
Animals ; Antibodies ; Calcitonin Gene-Related Peptide/metabolism ; Disease Models, Animal ; Ganglia, Spinal/*metabolism ; Intervertebral Disc/*drug effects/*injuries ; Intervertebral Disc Degeneration/metabolism ; Low Back Pain/*physiopathology ; Lumbar Vertebrae/injuries ; Male ; NAV1.7 Voltage-Gated Sodium Channel/*metabolism ; Neurons/*metabolism ; Pain/metabolism ; Rats ; Rats, Sprague-Dawley ; Stilbamidines

ObjectiveTo investigate the expressions of substance P (SP) and neurokinin-1 receptor (NK-1R) in the posterior horn of the L5－S2 spinal cord in the rat model of chronic nonbacterial prostatitis (CNP) at different time points of modeling.

METHODSForty adult male SD rats were randomly divided into four groups of equal number, control, 45 d model, 60 d model, and 90 d model, and proteins were obtained from the prostatic tissue of another 30 rats. The CNP model was made by intraperitoneal injection of 0.5 ml DPT vaccineand intradermal injection of mixed solution of 1 ml prostatein extract and complete adjuvant at a 1∶1 ratio, while the control rats were injected with the same volume of normal saline. At 45, 60, and 90 days after modeling, we measured the paw withdrawal threshold (PWT) of the rats, determined the levels of TNF-α, IL-1β, IL-2, and IL-10 in the prostate tissue by ELISA, observed the histomorphological changes in the prostate by transmission electron and light microscopy, and detected the expressions of SP and NK1-R in the L5－S2 spinal cord by immunohistochemistry.

RESULTSThe model rats showed significantly increased sensitivity to pain, with remarkably lowered PWT at 45, 60, and 90 days after modeling. The levels of TNF-α, IL-1β, IL-2, and IL-10 in the prostate tissue were markedly elevated in the CNP models as compared with those in the controls (all P<0.05), most significantly at 90 days (all P<0.05). Immunohistochemistry showed that the expressions of SP and NK-1R were remarkably higher in the CNP model groups than in the control (all P<0.05), the highest at 90 days. Light microscopy revealed no inflammatory cell infiltration in the prostate tissue of the control rats, and obvious edema and increased lymphocytes were observed with the prolonged time of modeling.Transmission electron microscopy showed inflammatory changes in the prostate tissue of the model rats and that peritubular interstitial edema was most obvious at 90 days, with widened intervals between peritubular cells and the epithelial base and increased numbers of fibroblasts and collagen fibrils.

CONCLUSIONSThe synthesis of SP and the level of NK-1R were increased in the posterior horn of the L5－S2 spinal cord in the rat model of CNP.

Animals ; Interleukin-10 ; metabolism ; Interleukin-1beta ; metabolism ; Interleukin-2 ; metabolism ; Male ; Pain ; Prostatitis ; metabolism ; physiopathology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Neurokinin-1 ; metabolism ; Spinal Cord ; metabolism ; Substance P ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

ObjectiveTo determine the zinc levels in the expressed prostatic secretion (EPS) of the patients with different types of chronic nonbacterial prostatitis, and explore the reference value of zinc concentration in EPS in the diagnosis and treatment of prostatitis.

METHODSWe collected EPS samples from 35 healthy men and 173 patients with chronic nonbacterial prostatitis, including 65 cases of type ⅢA, 69 cases of type ⅢB, and 39 cases of type Ⅳ, according to the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI). We compared the zinc levels in the EPS samples among different groups and analyzed the correlations of zinc concentration with the NIH-CPSI scores, WBC count, pH value, and age of the subjects.

RESULTSThe participants were aged 17－65 (32.5±8.5) years. The zinc concentrations in the EPS were significantly lower in the ⅢA (［162.2±10.8］ μg/ml) and ⅢB (［171.2±12.0］ μg/ml) than in the Ⅳ (［234.6±17.9］ μg/ml) (P<0.05 ) and the control group (［259.5±14.6］ μg/ml) (P<0.05 ). The zinc level was correlated negatively with the NIH-CPSI pain score (r=－0.248, P<0.01), quality of life score (r=－0.232, P<0.01), severity score (r=－0.270, P<0.01), total NIH-CPSI score (r=－0.281, P<0.01), and the pH value in EPS (r=－0.208, P<0.01), but showed no correlation with the WBC count and age of the subjects.

CONCLUSIONSThe reduced zinc concentration in the EPS of the patients with chronic nonbacterial prostatitis may be associated with the pain symptoms of the disease, which suggests the potential reference value of measuring the zinc concentration in EPS in the diagnosis and treatment of prostatitis.

Adolescent ; Adult ; Aged ; Chronic Disease ; Humans ; Male ; Middle Aged ; Pain ; metabolism ; Prostatitis ; metabolism ; physiopathology ; Quality of Life ; Young Adult ; Zinc ; metabolism

OBJECTIVETo explore the analgesic effect and action mechanism of electroacupuncture (EA) on gastric ulcer rats with liver-depression syndrome.

METHODSThrough open-field experimental method, 45 qualified SPF-grade male SD rats were selected and divided into a blank group, a model group and an EA group according to random number table method, 15 rats in each group. The model of gastric ulcer rats with liver-depression syndrome was established in the model group and the EA group by using chronic unpredictable stimulation combined with acetic acid burning method. Rats in the blank group did not receive intervention. Rats in the model group were treated with fixation and immobilization for 13 days. Rats in the EA group were treated with EA at "Liangqiu" (ST 34) and "Ganshu" (BL 18); EA voltage was 2 V; disperse-dense wave was selected with 4 Hz of disperse wave and 15 Hz of dense wave, and the intensity of EA was according to the slight vibration of local skin and; muscles; the needles were retained for 20 min, once a day for consecutive 6 days; there was an interval of 1 day' and the treatment was given for 2 weeks. The general condition, open-field experimental result and gastric ulcer index were observed; the western blotting method was applied to measure the expression of vanilloid receptor subtype 1 (VR1) in hypothalamus and gastric antral mucosal, and ELISA method was applied to test the expression of 5-hydroxytryptamine (5-HT) and norepinephrine (NE) in hippocampus.

RESULTSAfter model establishment, the general behavior condition in the model group was inferior to that in the blank group, which was obviously improved after EA. The range of motion in the model group was less than that in the blank group (P<0.01) while that in the EA group was higher than that in the model group (P<0.01). The ulcer inhibition rate was. 54.95%, and the ulcer index in the EA group was lower than that in the model group (P<0.01). Compared with; the blank group, the expression of VR1 in hypothalamus and gastric antral mucosal in the model group was increased (P<0.05); compared with the model group, the expression of VR1 in the EA group was reduced (P<0.05). Compared with the blank group, the expression of 5-HT an NE in hippocampus in the model group was significantly reduced (both P<0.01); compared with the model group, the expression of 5-HT and NE in the EA group was increased (both P<0.01).

CONCLUSIONEA at "Liangqiu" (ST 34) and "Ganshu" (BL 18) has certain analgesic effect in gastric ulcer rats with liver-depression syndrome, which is likely to be related with lowering the contents of VR1 in hypothalamus and gastric antral mucosal and increasing the content of 5-HT and NE in hippocampus.

Acupuncture Analgesia ; Acupuncture Points ; Animals ; Electroacupuncture ; Humans ; Liver ; physiopathology ; Male ; Nociceptive Pain ; genetics ; metabolism ; physiopathology ; therapy ; Rats ; Rats, Sprague-Dawley ; Serotonin ; metabolism ; Stomach Ulcer ; genetics ; metabolism ; physiopathology ; therapy ; TRPV Cation Channels ; genetics ; metabolism

PURPOSE: The TWIK-related spinal cord K+ channel (TRESK) has recently been discovered and plays an important role in nociceptor excitability in the pain pathway. Because there have been no reports on the TRESK expression or its function in the dorsal horn of the spinal cord in neuropathic pain, we analyzed TRESK expression in the spinal dorsal horn in a spinal nerve ligation (SNL) model. MATERIALS AND METHODS: We established a SNL mouse model by using the L5-6 spinal nerves ligation. We used real-time polymerase chain reaction and immunohistochemistry to investigate TRESK expression in the dorsal horn and L5 dorsal rot ganglion (DRG). RESULTS: The SNL group showed significantly higher expression of TRESK in the ipsilateral dorsal horn under pain, but low expression in L5 DRG. Double immunofluorescence staining revealed that immunoreactivity of TRESK was mostly restricted in neuronal cells, and that synapse markers GAD67 and VGlut2 appeared to be associated with TRESK expression. We were unable to find a significant association between TRESK and calcineurin by double immunofluorescence. CONCLUSION: TRESK in spinal cord neurons may contribute to the development of neuropathic pain following injury.
Animals ; Disease Models, Animal ; Hyperalgesia ; Ligation ; Male ; Neuralgia/*metabolism/physiopathology ; Neurons/metabolism ; Nociceptors ; Pain/metabolism/*physiopathology ; Potassium Channels/*metabolism ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction ; Spinal Cord Dorsal Horn/*metabolism ; Spinal Nerves/*injuries

OBJECTIVETo study the possible mechanisms of chronic nonbacterial prostatitis (CNP) pain.

METHODSCNP models were established in male Wistar rats by the autoimmune method. Then the paw withdrawal threshold (PWT) was detected using the Von Frey filament, prostate pathological examination was conducted, the expressions of substance P (SP) and transient receptor potential vanilloid 1 (TRPV1) in the prostate tissue and L5-S2 spinal segments were determined by immunohistochemistry and their correlations were analyzed.

RESULTSCompared with the control group, the CNP model rats showed markedly decreased PWT (P < 0.05) and obvious inflammation in the prostate tissue, with significant differences in the scope of lesion and interstitial lymphocyte infiltration (P < 0.05). The expressions of SP and TRPV1 in the prostate and spinal cord dorsal horn L5-S2 were remarkably upregulated in the models as compared with the control rats (P < 0.05). However, the expression of SP in the prostate was not correlated with that in the spinal cord (r = 0.099, P = 0.338), nor was that of TRPV1 (r = 0.000, P = 0.5).

CONCLUSIONSP and TRPV1 were involved in the formation and persistence of pain in CNP rats through their upregulated expressions in the L5-S2 spinal segments.

Animals ; Lumbosacral Region ; Male ; Neuralgia ; metabolism ; physiopathology ; Pain ; metabolism ; physiopathology ; Prostate ; metabolism ; Prostatitis ; metabolism ; physiopathology ; Rats ; Rats, Wistar ; Spinal Cord ; metabolism ; Substance P ; metabolism ; TRPV Cation Channels ; metabolism