Acute immune and non-immune inflammatory response in spontaneously hypertensive rats and normotensive rats. Role of endogenous nitric oxide

Does chronic pain alter the normal interaction between cardiovascular and pain regulatory systems? Pain modulation in the hypertensive-monoarthritic rat

Hypertension-associated hypoalgesia is widely recognized in acute pain conditions. In chronic pain states, however, the relationship between blood pressure and pain sensitivity is still ill-defined, with different authors reporting negative, positive, or even no relationship at all. This work addresses this issue, using complete Freund's adjuvant (CFA)-induced monoarthritis in different models of hypertension: Spontaneous (spontaneously hypertensive rats, SHR), induced by infusion of angiotensin II (ANG) or 1,3-dipropyl-8-sulfophenylxanthine (DPSPX, an adenosine receptors' antagonist), and renal artery ligation (RAL). Nociceptive responses associated with monoarthritis were evaluated by different behavioral tests (von Frey, ankle-bend and CatWalk) and by quantification of Fos expression at the dorsal horn upon noxious stimulation. In all hypertension models, higher von Frey thresholds and lower Fos expression were detected in hypertensive rats with chronic inflammatory pain, as compared to normotensive monoarthritic rats. In SHR and DPSPX, but not ANG or RAL models, hypertensive animals displayed lower inflammation than normotensives. Ankle-bend and CatWalk results indicated lower pain sensitivity in hypertensive rats only in SHR and DPSPX models. The present study shows the importance of using multiple models of hypertension, and evaluating pain responses by various methods, to better understand the complexity of the interactions between pain and cardiovascular regulatory systems.

PERSPECTIVE

This study used different models of hypertension to investigate whether chronic pain alters the normal integration of cardiovascular and pain regulatory systems. A complete understanding of the mechanisms underlying the complex interactions between these systems may disclose future therapeutic approaches to treat hypertension/chronic pain comorbidity states.

Effects of soy diet on inflammation-induced primary and secondary hyperalgesia in rat

Soy consumption is said to prevent or treat atherosclerosis, cancer, pain, and memory deficits, but experimental and clinical evidence to support these claims are lacking. We used in vivo models of inflammation to determine whether a soy diet reduces primary or secondary hyperalgesia. In all three experiments, rats were fed either a soy- or casein-based diet for at least 2 weeks before induction of inflammation and for the duration of experiments. Mechanical and heat paw withdrawal thresholds and edema were measured before and several times after induction of inflammation. Primary hyperalgesia was assessed in two models: unilateral intraplantar injection with 0.1 ml of 25% complete Freund's adjuvant (CFA) or 0.1 ml of 1% carrageenan. Unilateral injection of the intra-articular knee space with 25% CFA (0.1 ml) was used to determine the effects of soy in a model of secondary hyperalgesia. Following intraplantar injection of CFA, soy-fed animals exhibited significantly less paw edema, mechanical allodynia, and heat hyperalgesia compared to casein-fed animals. In the carrageenan model of paw inflammation, soy-fed animals were also less allodynic to mechanical stimuli, than were casein-fed animals, but showed no diet based differences in paw edema or heat hyperalgesia. Soy diet did not affect any of the outcome measures after the intra-articular injection of CFA. Our results suggest that a soy diet significantly decreases aspects of inflammation-induced primary, but not secondary, hyperalgesia in rats.

Repetitive H-wave device stimulation and program induces significant increases in the range of motion of post operative rotator cuff reconstruction in a double-blinded randomized placebo controlled human study

Background

Albeit other prospective randomized controlled clinical trials on H-Wave Device Stimulation (HWDS), this is the first randomized double-blind Placebo controlled prospective study that assessed the effects of HWDS on range of motion and strength testing in patients who underwent rotator cuff reconstruction.

Methods

Twenty-two patients were randomly assigned into one of two groups: 1) H-Wave device stimulation (HWDS); 2) Sham-Placebo Device (PLACEBO). All groups received the same postoperative dressing and the same device treatment instructions. Group I was given HWDS which they were to utilize for one hour twice a day for 90 days postoperatively. Group II was given the same instructions with a Placebo device (PLACEBO). Range of motion was assessed by using one-way ANOVA with a Duncan Multiple Range Test for differences between the groups preoperatively, 45 days postoperatively, and 90 days postoperatively by using an active/passive scale for five basic ranges of motions: Forward Elevation, External Rotation (arm at side), External Rotation (arm at 90 degrees abduction), Internal Rotation (arm at side), and Internal Rotation (arm at 90 degrees abduction). The study also evaluated postoperative changes in strength by using the Medical Research Council (MRC) grade assessed strength testing.

Results

Patients who received HWDS compared to PLACEBO demonstrated, on average, significantly improved range of motion. Results confirm a significant difference for external rotation at 45 and 90 days postoperatively; active range at 45 days postoperatively (p = 0.007), active at 90 days postoperatively (p = 0.007). Internal rotation also demonstrated significant improvement compared to PLACEBO at 45 and 90 days postoperatively; active range at 45 days postoperatively (p = 0.007), and active range at 90 days postoperatively (p = 0.006). There was no significant difference between the two groups for strength testing.

Conclusion

HWDS compared to PLACEBO induces a significant increase in range of motion in positive management of rotator cuff reconstruction, supporting other previous research on HWDS and improvement in function. Interpretation of this preliminary investigation while suggestive of significant increases in Range of Motion of Post -Operative Rotator Cuff Reconstruction, warrants further confirmation in a larger double-blinded sham controlled randomized study.

Arthritis induced by adjuvant in spontaneously hypertensive and normotensive rats: endogenous glucocorticoid effects on inflammatory response

The present study investigated arthritis induced by complete Freund adjuvant (AIA) in spontaneously hypertensive and normotensive rats (respectively, SHR and NTR rats). The inflammatory reaction was studied for 28 days by evaluating paw edema and secondary lesions found 10 days after complete Freund adjuvant (CFA) administration. The body weight of the animals and macroscopic alterations of several organs, including spleen, thymus, adrenal glands, and lymph nodes, were also analyzed. The results showed that the AIA manifestations were decreased in SHRs compared with NTRs. Moreover, this altered inflammatory response was not modified by surgical adrenalectomy.

The H-Wave((R)) Device Induces NODependent Augmented Microcirculation and Angiogenesis, Providing Both Analgesia and Tissue Healing in Sports Injuries

The hypothesis that the H-Wave(R) device (Electronic Waveform Lab, Inc., Huntington Beach, CA), a small-diameter fiber stimulator, is a paradigm shift of electrotherapeutic treatment of pain associated with human neuropathies and sports injuries is based on a number of its properties. The primary effect of H-Wave(R) device stimulation (HWDS) is the stimulation of "red-slow-twitch" skeletal muscle fibers. The authors propose, based on the unique waveform, that the H-Wave(R) device specifically and directly stimulates the small smooth muscle fibers within the lymphatic vessels ultimately leading to fluid shifts and reduced edema. In unpublished rat studies, it has been observed that HWDS induces protein clearance. The H-Wave(R) device was designed to stimulate an ultra low frequency (1-2 Hz), low tension, nontetanizing, and nonfatiguing contraction, which closely mimics voluntary or natural muscle contractions. The H-Wave(R) device can stimulate small fibers due in part to its exponentially decaying waveform and constant current generator activity. The main advantage of these technologies over currently applied electrical stimulators (eg, transcutaneous electrical nerve stimulator [TENS], interferential [IF], neuromuscular electrical stimulation [NMES], high-volt galvanic, etc.) is that H-Wave\'s(R) small fiber contraction does not trigger an activation of the motor nerves of the large white muscle fibers or the sensory delta and C pain nerve fibers, thus eliminating the negative and painful effects of tetanizing fatigue, which reduces transcapillary fluid shifts. Another function of the H-Wave(R) device is an anesthetic effect on pain conditions, unlike a TENS unit which in the short term activates a hypersensory overload effect (gate theory) to stop pain signals from reaching the thalamic region of the brain. When the H-Wave(R) device is used at high frequency (60 Hz), it acts intrinsically on the nerve to deactivate the sodium pump within the nerve fiber, leading to a long-lasting anesthetic/analgesic effect due to an accumulative postsynaptic depression. Moreover, HWDS produces a nitric oxide (NO)-dependent enhancement of microcirculation and angiogenesis in rats. Thus, the authors hypothesize that because of these innate properties of the H-Wave(R) device, it may provide a paradigm shift for the treatment of both short- and long-term inflammatory conditions associated with pain due to sports injuries. A recent meta-analysis found a moderate-to-strong effect of the H-Wave(R) device in providing pain relief, reducing the requirement for pain medication, and increasing functionality. The most robust effect was observed for improved functionality, suggesting that the H-Wave(R) device may facilitate a quicker return to the field.

KEYWORDS

H-Wave(R) device; sportsmedicine, nitric oxide-dependent blood flow; analgesia; angiogenesis.