Gq protein level increases concurrently with antigen-induced airway hyperresponsiveness in rats

Electroacupuncture improves cerebral blood flow and attenuates moderate ischemic injury via Angiotensin II its receptors-mediated mechanism in rats

BACKGROUND

To investigate the effects and potential mechanism of electroacupuncture intervention on expressions of Angiotensin II and its receptors-mediated signaling pathway in experimentally induced cerebral ischemia.

METHODS

Totally 126 male Wistar rats were randomly divided into control group, model group and EA group. The latter two were further divided into ten subgroups (n = 6) following Middle Cerebral Artery Occlusion (MCAO). Changes in regional cerebral blood flow (rCBF) and expressions of Angiotensin II and its receptors (AT1R, AT2R), as well as effector proteins in phosphatidyl inositol signal pathway were monitored before and at different times after MCAO.

RESULTS

MCAO-induced decline of ipsilateral rCBF was partially suppressed by electroacupuncture, and contralateral blood flow was also superior to that of model group. Angiotensin II level was remarkably elevated immediately after MCAO, while electroacupuncture group exhibited significantly lower levels at 1 to 3 h and the value was significantly increased thereafter. The enhanced expression of AT1R was partially inhibited by electroacupuncture, while increased AT2R level was further induced. Electroacupuncture stimulation attenuated and postponed the upregulated-expressions of Gq and CaM these upregulations. ELISA results showed sharply increased expressions of DAG and IP3, which were remarkably neutralized by electroacupuncture.

CONCLUSIONS

MCAO induced significant increases in expression of Angiotensin II and its receptor-mediated signal pathway. These enhanced expressions were significantly attenuated by electroacupuncture intervention, followed by reduced vasoconstriction and improved blood supply in ischemic region, and ultimately conferred beneficial effects on cerebral ischemia.

Airway smooth muscle as a target in asthma and the beneficial effects of bronchial thermoplasty

Airflow within the airways is determined directly by the lumenal area of that airway. In this paper, we consider several factors which can reduce airway lumenal area, including thickening and/or active constriction of the airway smooth muscle (ASM). The latter cell type can also contribute in part to inflammation, another feature of asthma, through its ability to take on a synthetic/secretory phenotype. The ASM therefore becomes a strategically important target in the treatment of asthma, given these key contributions to the pathophysiology of that disease. Pharmacological approaches have been developed to elicit relaxation of the ASM, but these are not always effective in all patients, nor do they address the long-term structural changes which impinge on the airway lumen. The recent discovery that thermal energy can be used to ablate smooth muscle has led to the development of a novel physical intervention—bronchial thermoplasty—in the treatment of asthma. Here, we review the evolution of this novel approach, consider some of the possible mechanisms that account for its salutary effects, and pose new questions which may lead to even better therapies for asthma.

Mammalian G proteins and their cell type specific functions

Heterotrimeric G proteins are key players in transmembrane signaling by coupling a huge variety of receptors to channel proteins, enzymes, and other effector molecules. Multiple subforms of G proteins together with receptors, effectors, and various regulatory proteins represent the components of a highly versatile signal transduction system. G protein-mediated signaling is employed by virtually all cells in the mammalian organism and is centrally involved in diverse physiological functions such as perception of sensory information, modulation of synaptic transmission, hormone release and actions, regulation of cell contraction and migration, or cell growth and differentiation. In this review, some of the functions of heterotrimeric G proteins in defined cells and tissues are described.

Effects of Repeated Antigen Exposure on Endothelin-1–Induced Bronchial Smooth Muscle Contraction and Activation of RhoA in Sensitized Rats

Changes in endothelin-1 (ET-1)-induced contraction and activation of RhoA in bronchial smooth muscle of repeatedly antigen-challenged rats, which exhibit marked airway hyperresponsiveness (AHR), were examined. The ET-1-induced contraction of bronchial smooth muscle was significantly enhanced in the repeatedly antigen-challenged group. In normal control animals, ET-1 induced time- and concentration-dependent translocation of RhoA to the plasma membrane, indicating activation of RhoA by ET-1 in rat bronchial smooth muscle. The level of ET-1-induced RhoA translocation was increased much more markedly in the AHR group than in the control animals. It is suggested that the augmented activation of RhoA observed in the hyperresponsive bronchial smooth muscle might be responsible for the enhanced ET-1-induced contraction of bronchial smooth muscle in AHR rats.

Augmented acetylcholine-induced translocation of RhoA in bronchial smooth muscle from antigen-induced airway hyperresponsive rats

Acetylcholine (ACh)-induced translocation of RhoA in bronchial smooth muscle of repeatedly antigen-challenged rats that have a marked airway hyperresponsiveness (AHR) was examined. ACh induced time- and concentration-dependent translocation of RhoA to the plasma membrane, indicating an activation of RhoA in bronchial smooth muscle. The level of ACh-induced RhoA translocation was further increased markedly in the AHR group as compared to that in the control group. It is suggested that the augmented activation of RhoA observed in the hyperresponsive bronchial smooth muscle might be responsible for the enhanced ACh-induced Ca(2+) sensitization of bronchial smooth muscle contraction associated with AHR.

Possible involvement of G(i3) protein in augmented contraction of bronchial smooth muscle from antigen-induced airway hyperresponsive rats

To investigate a possible involvement of pertussis toxin (PTX)-sensitive heterotrimeric G proteins in the pathogenesis of airway hyperresponsiveness, the effect of PTX treatment on the augmented contractile response to acetylcholine (ACh) in bronchial smooth muscle of antigen-induced airway hyperresponsive rats was determined. In bronchial smooth muscle of airway hyperresponsive rats that were actively sensitized and repeatedly challenged with 2,4-dinitrophenylated Ascaris suum antigen, ACh-induced contractions were markedly augmented. The augmented contractile responses in the airway hyperresponsive group were significantly inhibited after treatment with PTX (1 microg/mL for 6 hr, 37 degrees ), whereas only a slight attenuation was observed in the normal control group. The level of G(alpha)i3 (measured by immunoblotting), but not other alpha-subunits of G(i/o) family proteins, in bronchial smooth muscle of the airway hyperresponsive rats was significantly increased as compared with that of control animals. It is concluded that PTX-sensitive muscarinic contractile responses of bronchial smooth muscle might be augmented upon antigen-induced airway hyperresponsiveness in rats, probably due to an up-regulation of G(alpha)i3 protein of bronchial smooth muscle.