Sex differences in cough reflex.

Majority of patients visiting cough clinics are postmenopausal women, who are affected by intractable cough for years. Why the cough reflex becomes exaggerated in women is not known. Basic research excludes females from the studies contributing to the sex bias which may be responsible for lack of understanding of "hypersensitive" cough in women. Biological and behavioural differences between women and men are the factors affecting cough physiology. Gender also shapes the patterns of behaviour and determines the character of environmental exposures which differs between sexes. The article offers an insight into the physiology of the cough, differences in the maturation of it and biological, social and behavioural factors contributing to the sex differences in cough.

The Guinea Pig Sensitized by House Dust Mite: A Model of Experimental Cough Studies.

The guinea pig sensitized by ovalbumin is the most widely used model to study cough experimentally, as the neurophysiology of the vagus nerve in the guinea pig is closest to humans. Nonetheless, the choice of the antigen remains questionable, which influences the translation of results into clinical medicine. The present study seeks to develop an alternative model of cough study using house dust mite sensitization (HDM). Thirty guinea pigs were divided into the HDM group, ovalbumin (OVA) group, and control group based on their cough response to 0.4 M citric acid. In the HDM group animals were sensitized by 0.25 %HDM aerosol, which they inhaled for 5 min over 5 days, followed by inhalation of 0.5 %HDM in the same protocol. Sensitization was confirmed by a skin test. Symptoms of allergic rhinitis were induced by intranasal application of 15 µl 0.5 %HDM and cough challenges with citric acid were performed. Airway resistance was measured in vivo by Pennock's method. We found that both HDM and OVA-sensitized groups showed a significantly enhanced nasal reactivity and cough response compared with controls. The airway resistance data did not show significant differences. We conclude that the HDM cough model replicates functional aspects of the OVA model, which may make it an alternative to the latter. However, the superiority of the HDM model for experimental cough studies remains to be further explored.

Chronic Cough as a Female Gender Issue.

Cough accompanying acute respiratory tract disorders is a self-limiting phenomenon, and it usually does not require sophisticated management. Chronic cough, in contrast, is a bothersome problem, considerably influencing the quality of life of affected individuals. Specialized cough clinics report that substantial proportion of their patients are middle aged-to-postmenopausal females who cough for years in response to otherwise non-tussigenic stimuli, without a clear underlying disease reason. A newly established entity - 'cough hypersensitivity syndrome' explains pathogenesis of this problem. However, the syndrome has not been generally accepted, and the guidelines regarding the diagnostic protocols and treatment are not yet available. The reason why females cough more than males do is unclear, but the analysis of literature and experience with the chronic cough patients allows selecting three main targets of hormonal background which can contribute to the enhanced coughing in females. They are as follows: increased activity of transient receptor potential (TRP) channels expressed on vagal C-fibers mediating cough, laryngeal hypersensitivity and laryngeal dysfunction with paradoxical vocal cord movement, and mast cells which are known to express receptors for female sexual hormones and are frequently found in the bronchoalveolar lavage in chronic cough patients. In this review we analyze the potential contribution of the factors above outlined to excessive cough in female subjects.