Effects of Psychological Stress and Fluoxetine on Development of Oral Candidiasis in Rats

Abstract

Psychological stress has been found to suppress cell-mediated immune responses that are important for limiting the proliferation of Candida albicans. Fluoxetine has been observed to reduce negative consequences of stress on the immune system in experimental and clinical models, but there are no data on its effects on oral candidiasis. We designed experiments to evaluate the effects of fluoxetine on the development of oral candidiasis in Sprague-Dawley rats exposed to a chronic auditory stressor. Animals were submitted to surgical hyposalivation in order to facilitate the establishment and persistence of C. albicans infection. Stress application and treatment with drugs (placebo or fluoxetine) were initiated 7 days before C. albicans inoculation and lasted until the end of the experiments, on day 15 postinoculation. Establishment of C. albicans infection was evaluated on days 2 and 15 after inoculation. Tissue injury was determined by the quantification of the number and type (normal or abnormal) of papillae on the dorsal tongue per microscopic field. A semiquantitative scale was devised to assess the degree of colonization of the epithelium by fungal hyphae. Our results showed that stress exacerbates C. albicans infection in the tongues of rats. Significant increases in Candida counts, the percentage of the tongue's surface covered with clinical lesions, the percentage of abnormal papillae, and the colonization of the epithelium by hyphae were found in stressed rats compared to the nonstressed ones. Treatment with fluoxetine significantly reversed these adverse effects of stress. Besides the psychopharmacological properties of fluoxetine against stress, it has consequences for Candida infection.

Reply to letter to the editor

“…(b) The intraoral image of the lesion on the 20th day of the follow-up that was sent by the patient. c. The intraoral image of the lesion on the 40th day at the end of the treatment that was sent by the patient ulcer, the medications, and the contribution of psychological stress to immunosuppression (Núñez, Novío, Suárez, Balboa, & Freire-Garabal, 2010;Rodríguez-Galán et al, 2010), we concluded that the possibility of an atypical oral ulcer inducted by candida infection was high. She was advised to give up complete denture use and stop the local corticosteroid treatment.…”

Role of chronic stress and depression in periodontal diseases

“… also found that injection of lipopolysaccharide provoked a significant increase in the circulating levels of corticosterone and alterations in cytokine levels, consistent with dysregulation of the immune system, in an animal model of depression. Psychological stress has been also shown to exacerbate oral infection with the opportunistic pathogen, Candida albicans , in rodents .…”

Recent mouse and rat methods for the study of experimental oral candidiasis

“…Since psychological stress has been found to suppress cell-mediated immune responses that are important for limiting the proliferation of C. albicans, Núnez et al 54 evaluated the effects of stress on oral candidiasis in rats exposed to a repeated auditory stressor. The results showed that stress exacerbated C. albicans infection in the tongue dorsum of the rats.…”