A new instrument for measuring pressure pain strength to different bodily parts is introduced in this paper. For a new measuring appliance, it can be used conveniently for detection and evaluation of a patient's pressure pain threshold value, and for the research of bodily channels and network vessels. The system uses silicone oil as pressure conducting medium of a transducer, and five pressure detecting probes with different surface areas are designed to meet the requirements of the parts to be measured. The system has digital lock function for easy operation.
Humans ; Pain ; physiopathology ; Pain Measurement ; instrumentation ; Pain Threshold ; physiology ; Pressure ; Sensitivity and Specificity ; Silicone Oils

OBJECTIVE: To detect the activation pattern of the thalamus in human by the functional magnetic resonance imaging (fMRI) with the electrical stimulation of different intensities, and to explore the mechanism of this area in pain modulation. METHODS: Ten healthy right-handed volunteers were given different electrical stimulations of 1-, 2-, and 3- times pain threshold respectively. The whole-brain was scanned simultaneously by GE 1.5T magnetic resonance imaging system. The data were postprocessed by analysis of functional neuroimages (AFNI) to establish the regional activity maps of the thalamus. RESULTS: Patterns of functional activity showed a positive linear relationship between the activation signals and stimulation intensity in bilateral thalamus, whereas the BOLD signal of bilateral medial thalamus demonstrated that the curve was similar to the exponential function. Meanwhile, the activation in the contralateral lateral thalamus (cThl), but not the contralateral medial thalamus (cThm), was prominent compared with the corresponding ipsilateral subregions, and only the lateral thalamus displayed a contralateral biased representation while the medial thalamus lacked this property. CONCLUSION Thalamus is one of the vital components in the pain modulation network, which can present spatial segregation activations with unique characteristics of stimulation intensity-response in each subregion. All the results are helpful to understand the crucial role of thalamus in processing the pain information.
Adult ; Electric Stimulation ; Female ; Humans ; Magnetic Resonance Imaging ; Male ; Pain ; physiopathology ; Pain Threshold ; Thalamus ; physiology

OBJECTIVES: This study aimed to investigate whether the microglia in the spinal trigeminal nucleus caudal part (Sp5C) were activated in a rat model of trigeminal neuralgia and to explore whether the activation level of microglia is consistent with maxillofacial pain level. METHODS: Chronic constriction injury of trigeminal nerve (CCI) was induced by partial ligation of infraorbital nerve (IoN) in rats. The behavioral change of rats observed at D1, D5, D10, D15, and D30 days post-surgery and the change of pain threshold were detected with electronic Von Frey filaments served as an evaluation index of maxillofacial pain. Weight change was measured by weighing. Ionized calcium binding adaptor molecule-1 (Iba-1) expression level of Sp5C at each time point was detected, and three microglia morphological categories were analyzed by immunohistochemical staining. RESULTS: The changes of behavioral and pain threshold suggested the maxillofacial pain level first increased and then decreased post-surgery in the IoN-CCI group. Both the expressions of Iba-1 and proportion of ameboid morphology in ipsilateral Sp5C increased from D1 and reached their peaks in D10 and D5, respectively. Then, they recovered nearly to the same level with contralateral Sp5C on D30. This trend was consistent with the maxillofacial change. CONCLUSIONS The model of trigeminal neuralgia in rats constructed by partial ligation of infraorbital nerve can induce the activation of microglia in Sp5C, and the activation level is consistent with maxillofacial pain, which reached its peak at around D10 post-surgery.
Rats ; Animals ; Trigeminal Neuralgia ; Rats, Sprague-Dawley ; Microglia ; Pain Threshold/physiology* ; Pain

Empathy, a basic prosocial behavior, is referred to as an ability to understand and share others' emotional state. Generally, empathy is also a social-behavioral basis of altruism. In contrast, impairment of empathy development may be associated with autism, narcissism, alexithymia, personality disorder, schizophrenia and depression. Thus, study of the brain mechanisms of empathy has great importance to not only scientific and clinical advances but also social harmony. However, research on empathy has long been avoided due to the fact that it has been considered as a distinct feature of human beings from animals, leading to paucity of knowledge in the field. In 2006, a Canadian group from McGill University found that a mouse in pain could be shared by its paired cagemate, but not a paired stranger, showing decreased pain threshold and increased pain responses through emotional contagion while they were socially interacting. In 2014, we further found that a rat in pain could also be shared by its paired cagemate 30 min after social interaction, showing long-term decreased pain threshold and increased pain responses, suggesting persistence of empathy for pain (empathic memory). We also mapped out that the medial prefrontal cortex, including the anterior cingulate cortex, prelimbic cortex and infralimbic cortex, is involved in empathy for pain in rats, suggesting that a neural network may be associated with development of pain empathy in the CNS. In the present brief review, we give a brief outline of the advances and challenges in study of empathy for pain in humans and animals, and try to provide a novel bio-psychosocial-behavioral model for study of pain and its emotional comorbidity using laboratory animals.
Animals ; Cerebral Cortex ; physiology ; Emotions ; Empathy ; Gyrus Cinguli ; physiology ; Humans ; Mice ; Models, Animal ; Pain ; Pain Threshold ; Prefrontal Cortex ; physiology ; Rats

Animals ; Cocaine ; pharmacology ; Habenula ; drug effects ; physiology ; Neurons ; drug effects ; physiology ; Pain Threshold ; drug effects ; Rats

OBJECTIVETo investigate the possible relationship between the analgesic effect of acupuncture and connexin 43.

METHODSConnexin 43 gene knock-out mice were divided into 4 groups: a wide type (WT) control group, a WT acupuncture group, a heterozygous (HT) control group and HT acupuncture group. Hot-plate test and writhing response induced by acetic acid were used for investigating the analgesic effect of acupuncture.

RESULTSThere was no significant difference in the basic pain threshold value between HT and WT mice (P > 0.05). Acupuncture could significantly increase the pain threshold value, prolong the latency period of writhing body and decrease the number of writhing body as compared with pre-acupuncture in WT and HT mice (P < 0.01 or P < 0.05). The pain threshold, latency period of writhing and number of writhing body in HT mice were less than WT mice post-acupuncture (P < 0.05).

CONCLUSIONConnexin 43 gene knock-out might partially inhibit the analgesic effect of acupuncture, suggesting that connexin 43 is possibly related with meridians and the effect of acupuncture.

Acupuncture Analgesia ; Animals ; Connexin 43 ; genetics ; physiology ; Female ; Gap Junctions ; physiology ; Male ; Mice ; Pain Threshold

Animals ; Electric Stimulation ; Neurons ; pathology ; physiology ; Pain Threshold ; Rats ; Rats, Sprague-Dawley ; Red Nucleus ; pathology ; physiology

OBJECTIVETo delineate the influence of transcutaneous electrical nerve stimulation (TENS) on heat pain threshold and vibration threshold in human.

METHODSTwenty healthy, young subjects, aged from 20 to 39, participated in the study. They were randomly allocated into either TENS or placebo group. Thirty minutes of conventional TENS (200 micro s pulses at 100 Hz and 2 - 3 times sensory threshold) or placebo stimulation was applied to the acupuncture points (LI4) on each subject's left hand. Heat pain and vibration thresholds were measured using Medoc TSA-2001 and VSA-3000 respectively on the thenar eminence of each subject's left hand. These assessments were done at 30, 20 and 10 minutes before and 0, 10, 20, 30, 40 and 50 minutes after 30 minutes of TENS or placebo treatment.

RESULTSThis study showed a significant increase in heat pain threshold by 0.81 degrees C and 1.54 degrees C respectively at 0 (P = 0.002) and 20 minutes (P = 0.004) after 30 minutes of TENS application to the LI4 acupoint of young healthy subjects, compared with placebo stimulation. Interestingly, no significant difference in vibration threshold was found between the TENS and placebo groups.

CONCLUSIONThe effect of TENS on the acupoint is to reduce pain but not tactile (specifically vibration) sensibility.

Acupuncture Points ; Adult ; Female ; Hot Temperature ; Humans ; Male ; Pain Threshold ; physiology ; Transcutaneous Electric Nerve Stimulation ; Vibration

This study was done to evaluate differences in pressure pain threshold, grip strength, manual dexterity and touch pressure threshold in the dominant and non-dominant hands of right- and left-handed subjects, and to compare findings within and between these groups. Thirty-nine right-handed and twenty-one left-handed subjects participated in the study. Pressure pain threshold was assessed using a dolorimeter, grip strength was assessed with a hand-grip dynamometer, manual dexterity was evaluated using the VALPAR Component Work Sample-4 system, and touch pressure threshold was determined using Semmes Weinstein monofilaments. Results for the dominant and non-dominant hands were compared within and between the groups. In the right-handed subjects, the dominant hand was significantly faster with the VALPAR Component Work Sample-4, showed significantly greater grip strength, and had a significantly higher pressure pain threshold than the non-dominant hand. The corresponding results for the two hands were similar in the left-handed subjects. The study revealed asymmetrical manual performance in grip strength, manual dexterity and pressure pain threshold in right-handed subjects, but no such asymme-tries in left-handed subjects.
Adult ; Female ; Hand/innervation/*physiology ; Hand Strength/*physiology ; Humans ; Laterality/*physiology ; Male ; Motor Skills/*physiology ; Pain Threshold/*physiology ; Physical Stimulation ; Touch/*physiology

Acupuncture Analgesia ; Animals ; Central Nervous System ; metabolism ; Electroacupuncture ; Nitric Oxide ; metabolism ; Pain Threshold ; physiology ; Rats ; Rats, Wistar