The beta(2)-agonist salbutamol inhibits bronchoconstriction and leukotriene D(4) synthesis after dry gas hyperpnea in the guinea-pig

Leukotriene Signaling as a Target in α-Synucleinopathies

Parkinson’s disease (PD) and dementia with Lewy bodies (DLB) are two common types of α-synucleinopathies and represent a high unmet medical need. Despite diverging clinical manifestations, both neurodegenerative diseases share several facets of their complex pathophysiology. Apart from α-synuclein aggregation, an impairment of mitochondrial functions, defective protein clearance systems and excessive inflammatory responses are consistently observed in the brains of PD as well as DLB patients. Leukotrienes are lipid mediators of inflammatory signaling traditionally known for their role in asthma. However, recent research advances highlight a possible contribution of leukotrienes, along with their rate-limiting synthesis enzyme 5-lipoxygenase, in the pathogenesis of central nervous system disorders. This review provides an overview of in vitro as well as in vivo studies, in summary suggesting that dysregulated leukotriene signaling is involved in the pathological processes underlying PD and DLB. In addition, we discuss how the leukotriene signaling pathway could serve as a future drug target for the therapy of PD and DLB.

Bronchodilator response in patients with persistent allergic asthma could not predict airway hyperresponsiveness

: Anticholinergics, or specific antimuscarinic agents, by inhibition of muscarinic receptors cause bronchodilatation, which might correlate with activation of these receptors by the muscarinic agonist methacholine. The aim of this study was to determine whether a positive bronchodilator response to the anticholinergic ipratropium bromide could predict airway hyperresponsiveness in patients with persistent allergic asthma. The study comprised 40 patients with mild and moderate persistent allergic asthma. Diagnosis was established by clinical and functional follow-up (skin-prick test, spirometry, bronchodilator tests with salbutamol and ipratropium bromide, and methacholine challenge testing). The bronchodilator response was positive to both bronchodilator drugs in all patients. After salbutamol inhalation, forced expiratory volume in 1 second (FEV1) increased by 18.39 +/- 6.18%, p < .01, whereas after ipratropium bromide, FEV1 increased by 19.14 +/- 6.74%, p < .01. The mean value of FEV1 decreased by 25.75 +/- 5.16%, p < .01 after methacholine (PC20 FEV1 [provocative concentration of methacholine that results in a 20% fall in FEV1] from 0.026 to 1.914 mg/mL). Using linear regression, between methacholine challenge testing and bronchodilator response to salbutamol, a positive, weak, and stastistically significant correlation for FEV1 was found (p < .05). Correlations between methacholine challenge testing and the bronchodilator response to ipratropium bromide were positive and weak but not statistically significant. The positive bronchodilator response to ipratropium bromide could not predict airway hyperresponsiveness.

Elevating dietary salt exacerbates hyperpnea-induced airway obstruction in guinea pigs

Previous studies have indicated that increased dietary salt consumption worsens postexercise pulmonary function in humans with exercise-induced asthma (EIA). It has been suggested that EIA and hyperpnea-induced airway obstruction (HIAO) in guinea pigs (an animal model of EIA) are mediated by similar mechanisms. Therefore, the purpose of this study was to determine whether altering dietary salt consumption also exacerbated HIAO in guinea pigs. Furthermore, the potential pathway of action of dietary salt was investigated by blocking leukotriene (LT) production during HIAO in guinea pigs. Thirty-two male Hartley strain guinea pigs were split into two groups. One group (n = 16) of animals ingested a normal-salt diet (NSD) for 2 wk; the other group (n = 16) ingested a high-salt diet (HSD) for 2 wk. Thereafter, animals were anesthetized, cannulated, tracheotomized, and mechanically ventilated during a baseline period and during two dry gas hyperpnea challenges. After the first challenge, the animals were administered either saline or nordihydroguaiaretic acid, a LT inhibitor. Bladder urine was analyzed for electrolyte concentrations and urinary LTE(4). The HSD elicited higher airway inspiratory pressures (Ptr) than the NSD (P < 0.001) postchallenge. However, after infusion of the LT inhibitor and a second hyperpnea challenge, HIAO was blocked in both diet groups (P < 0.001). Nonetheless, the HSD group continued to demonstrate slightly higher Ptr than the NSD group (P < 0.05). Urinary LTE(4) excretion significantly increased in the HSD group compared with the NSD group within treatment groups. This study has demonstrated that dietary salt loading exacerbated the development of HIAO in guinea pigs and that LT release was involved in HIAO and may be moderated by changes in dietary salt loading.