Role of muscle spindle in weightlessness-induced amyotrophia and muscle pain

To date, the medium and long-term space flight is urgent in need and has become a major task of our manned space flight program. There is no doubt that medium and long-term space flight has serious damaging impact upon human physiological systems. For instance, atrophy of the lower limb anti-gravity muscle can be induced during the space flight. Muscle atrophy significantly affects the flight of astronauts in space. Most importantly, it influences the precise manipulation of the astronauts and their response capacity to emergencies on returning to the atmosphere from space. Muscle atrophy caused by weightlessness may also seriously disrupt the normal life and ＇work of the astronauts during the re-adaptation period. Here we summarize the corresponding research concentrating on weightlessness-induced changes of muscular structure and function. By combining research on muscle pain, which is a common clinical pain disease, we further provide a hypothesis concerning a dynamic feedback model of ＂weightlessness condition → muscular atrophy ←→ muscle pain＂. This may be useful to explore the neural mechanisms underlying the occurrence and development of muscular atrophy and muscle pain, through the key study of muscle spindle, and furthermore provide more effective therapy for clinical treatment.

Inhibition of Muscular Nociceptive Afferents via the Activation of Cutaneous Nociceptors in a Rat Model of Inflammatory Muscle Pain

Topical irritants such as capsaicin(CAP),peppermint oil(PO),and mustard oil(MO)are effective in relieving inflammatory muscle pain.We investigated the effects of topical irritants in a rat model of inflammatory muscle pain produced by injecting complete Freund's adjuvant(CFA)into the tibialis anterior muscle.CFAinduced mechanical hypersensitivity and the spontaneous activity of muscular nociceptive afferents,and decreased weight-bearing of the hindlimb were relieved by topical application of CAP,PO,or MO on the skin overlying the inflamed muscle.The effects of topical irritants were abolished when applied to the skin on the ipsilateral plantar region or on the contralateral leg,or when the relevant cutaneous nerve or dorsal root was transected.Our results demonstrated that topical irritants may alleviate inflammatory muscle pain via activating cutaneous nociceptors and subsequently inhibiting the abnormal activity of muscular nociceptive neurons.

Chronic Consequences of Uncomplicated Yersinia Enterocolitica Infection:A Retrospective Study(2004)of Military Recruits Previously(1987)Screened for Antibodies to Yersinia Enterocolitica O:3

In 1987, a serological survey among 755 male Norwegian military recruitsshowed that 68 (9.0%) had IgG (7.4%) and / or IgA (4.5%) antibodiesto Y.enterocolitica O:3, consistent with previous infection.In 2004,433 of the former recruits (mean age 37.5 years, range 35 - 42 years) answered a questionnaire, in order to investigatedevelopment of possible chronic disorders and complaints related to uncomplicated Y.enterocolitica infection. The questionnaire covered per-sonal and demographic data, behavioral risk factors, and possible chronic complaints related to yersiniosis.Among the 433 responders, 51 (11.8%) were seropositive for IgG or IgA in the 1987 survey, 380 were seronegative, and 2 had ambiguous results.No difference was observed between the seropositive and seronegativegroups regarding education, annual income, general behavioral risk factors like smoking, alcohol consumption, physical activity, and dietary parameters;or diagnosed chronic illness. However, the seropositives weresignificantly more likely than the seronegatives to report recurrent diarrhea, painful or swollen joints, and muscle pain. Also, presence of all three complaints was more common among seropositives. Conclusion: The present study shows that uncomplicated Y.enterocolitica O:3 infection is a risk factor regarding future development of chronic complaintssuch as diarrhea, and joint and muscle complaint.

Effect of Electroacupuncture Combined with Tuina on Lumbar Muscle Tone in Patients with Acute Lumbar Sprain

Objective: To observe the clinical effect of electroacupuncture(EA)combined with tuina on acute lumbar sprain and lumbar muscle tone before and after treatment. Methods: A total of 130 acute lumbar sprain cases were randomly allocated into an observation group and a control group, 65 in each group. Cases in the observation group were treated with EA combined with tuina, whereas cases in the control group were treated with Diclofenac Sodium Dual Release Enteric-coated capsules. The muscle tones in two groups were tested before and after treatment. Results: The recovery rate and overall response rate in the observation group were 66.2% and 93.8% respectively, versus 56.9% and 87.7% in the control group, showing no between-group statistical significances(P>0.05). After treatment, the force-displacement area under curve(AUC) in both groups showed a significance difference(P<0.05). Conclusion: Both EA combined with tuina and aforementioned oral medication have remarkable effects for acute lumbar sprain, and the former can better improve the lumbar muscle tone in patients with acute lumbar sprain.