Effect Of Complete Freund's Adjuvant Research Articles

Acupuncture alleviates acid- and purine-induced pain in rodents.

Background and PurposeWe set out to investigate the effects of electroacupuncture (EAP) and moxibustion on pain states mediated by a range of acid‐ and ATP‐sensitive nociceptors in acute and inflammatory rodent pain models.Experimental ApproachWe injected PBS (pH 6.0 or 4.0) or α,β‐methylene ATP into the paw of rats or mice to cause thermal hypersensitivity, which was quantified by the paw withdrawal latency (PWL). Inflammatory pain was induced by the injection of complete Freund's adjuvant (CFA) into the rat paw.Key ResultsEAP and moxibustion counteracted the decrease of PWL mediated by acid‐sensing ion channel 3 (ASIC3) and transient receptor potential vanilloid 1 (TRPV1) channels in response to pH 6.0 PBS, but not that mediated by TRPV1 channels only, initiated by the injection of pH 4.0 PBS. Similarly, EAP and moxibustion prevented the purinergically induced pain which was caused by stimulation of P2X3 (P2X2/3) and P2X7 receptors. The effect of CFA was also relieved by EAP and moxibustion.Conclusions and ImplicationsDuring acute thermal pain and CFA‐induced inflammatory pain, ASIC3/TRPV1 channels and P2X3/P2X7 receptors are activated by protons and exogenous α,β‐methylene ATP or endogenously released ATP respectively. Low‐threshold acute acidic pain mediated by the activation of ASIC3/TRPV1 channels was reversed by EAP/moxibustion, while high‐threshold acidic pain that is mediated exclusively by the activation of TRPV1 channels was not. ASIC3 and P2X3 receptors appear to interact with each other in responding to both protons and ATP, by forming an ASIC3/P2X3 “cognate receptor”, sensitive to EAP/moxibustion.

Inflammation induces Epac-protein kinase C alpha and epsilon signaling in TRPV1-mediated hyperalgesia.

The exchange proteins activated by cAMP (Epacs) have been shown to play important roles in producing inflammation-induced nociception. Transient receptor potential vanilloid type 1 (TRPV1) is a major receptor processing thermal and chemosensitive nociceptive information. The role of Epacs in modulating the activity of TRPV1 has yet to be determined. Studying the effect of complete Freund adjuvant (CFA)-induced inflammation on capsaicin-activated TRPV1 nociceptive responses in dorsal root ganglia (DRG), we found that CFA produced a large increase in capsaicin-induced responses. The increase was inhibited by Epac1 and Epac2 antagonists. Thus, activation of Epacs is critical in producing enhancement in TRPV1-mediated responses under inflammatory conditions. In addition, the inflammation-induced enhancement of TRPV1 responses was blocked by PKCα and PKCε inhibitors, suggesting the essential roles of these PKCs in enhancing TRPV1 responses. To determine the mechanism underlying the Epac actions on TRPV1, we studied the effects of the Epac activator, 8-(4-chlorophenylthio)-2-O-methyl-cAMP (CPT), on capsaicin-induced nociceptive behavioral responses, capsaicin-activated currents, expression and membrane trafficking of PKC and TRPV1 in DRG. CPT was found to enhance capsaicin-induced nociception and ionic currents. The enhancement was inhibited by PKCα and PKCε inhibitors. In addition, CPT increased the expression of phosphorylated PKCα (pPKCα) and membrane TRPV1 expression in DRG. Studying the colocalization of TRPV1 and pPKCα or pPKCε in DRG slices prepared from CFA-treated rats, we found that pPKCα or pPKCε expressed with TRPV1 in different-sized neurons to exert differential influences on TRPV1 activity. Thus, Epac-PKC signaling is critically important in producing inflammation-induced potentiation of TRPV1 functions.

Sustained pain-related depression of behavior: effects of intraplantar formalin and complete freund's adjuvant on intracranial self-stimulation (ICSS) and endogenous kappa opioid biomarkers in rats.

BackgroundIntraplantar administration of complete Freund's adjuvant (CFA) and formalin are two noxious stimuli commonly used to produce sustained pain-related behaviors in rodents for research on neurobiology and treatment of pain. One clinically relevant manifestation of pain is depression of behavior and mood. This study compared effects of intraplantar CFA and formalin on depression of positively reinforced operant behavior in an assay of intracranial self-stimulation (ICSS) in rats. Effects of CFA and formalin on other physiological and behavioral measures, and opioid effects on formalin-induced depression of ICSS, were also examined.ResultsThere were four main findings. First, consistent with previous studies, both CFA and formalin produced similar paw swelling and mechanical hypersensitivity. Second, CFA produced weak and transient depression of ICSS, whereas formalin produced a more robust and sustained depression of ICSS that lasted at least 14 days. Third, formalin-induced depression of ICSS was reversed by morphine doses that did not significantly alter ICSS in saline-treated rats, suggesting that formalin effects on ICSS can be interpreted as an example of pain-related and analgesic-reversible depression of behavior. Finally, formalin-induced depression of ICSS was not associated with changes in central biomarkers for activation of endogenous kappa opioid systems, which have been implicated in depressive-like states in rodents, nor was it blocked by the kappa antagonist norbinaltorphimine.ConclusionsThese results suggest differential efficacy of sustained pain stimuli to depress brain reward function in rats as assessed with ICSS. Formalin-induced depression of ICSS does not appear to engage brain kappa opioid systems.Electronic supplementary materialThe online version of this article (doi:10.1186/1744-8069-10-62) contains supplementary material, which is available to authorized users.

Immune reproductive failure: effect of nonspecific immunostimulation in mouse model.

There is much evidence that pregnancy loss may be immunologically mediated. Failure of the maternal immune system to actively support the pregnancy may be responsible for its demise. Potentiation of immune functions has been attempted in humans; however, the success of immunotherapy is still not clear. Thus immunotherapy experiments in mouse models are important. Nonspecific immuno-stimulation with complete Freund adjuvant (CFA) was shown in our laboratory to reverse the tendency to fetal loss in the CBA/J X DBA/2J mouse combination. CFA elevates the non-T lymphocyte population, decreases T-cell secreted lymphokines, and enhances macrophage-secreted monokines. However, a relationship between these changes and a beneficial effect of CFA on reproductive performance has to be proved. Information obtained from nonspecific immunopotentiation in the CBA/J-DBA/2J model may contribute the assessment of nonspecific immunotherapy in humans.

Increased Bone Marrow Production of Granulocytes and Mononuclear Phagocytes Induced by Mycobacterial Adjuvants: Improved Recovery of Leukopoiesis in Mice After Cyclophosphamide Treatment

The effects of complete Freund adjuvant (CFA) or Mycobacterium bovis BCG on leukopoiesis and on leukopoietic recovery from cyclophosphamide treatment in mice was studied. CFA injected subcutaneously or intraperitoneally resulted in increased blood granulocyte and monocyte counts, increased numbers of bone marrow granulocyte and mononuclear phagocyte progenitors, and increased hematopoietic colony-stimulating factor in the serum. Furthermore, the quantitative cellular response within 24 h to an induced sterile intraperitoneal inflammation (thioglycolate) was augmented by subcutaneous CFA. In mice given CFA subcutaneously, blood granulocyte counts, as well as the peritoneal granulocyte and macrophage response to intraperitoneal thioglycolate, recovered more quickly than did those of the controls after a 250-mg/kg dose of cyclophosphamide. CFA-treated mice consistently maintained blood granulocyte and monocyte counts 1.3-to 4-fold higher than those of the controls for 2 weeks while receiving 75 mg of cyclophosphamide per kg every other day. Mice pretreated with CFA intraperitoneally had higher numbers of bone marrow colony-forming units in culture and higher levels of serum colony-stimulating factor after 250-mg/kg injections of cyclophosphamide. Similarly, BCG resulted in increased bone marrow colony-forming units in culture, increased serum colony-stimulating factor, and a faster return of the peritoneal inflammatory response after cyclophosphamide injection. These results show that mycobacterial adjuvants accelerate recovery of leukopoietic functions after cyclophosphamide treatment and suggest a mechanism whereby such adjuvants afford nonspecific protection against infection in immunosuppressed mice.