Chronic dexamethasone exposure retards growth without altering the digestive tract microbiota composition in goats

Canfeng Hua,Yali Geng,Qu Chen,Liqiong Niu,Yingdong Ni,Shiyu Tao,Ruqian Zhao,Liuping Cai

doi:10.1186/s12866-018-1253-1

Canfeng Hua, Yali Geng + Show 6 more

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https://doi.org/10.1186/s12866-018-1253-1

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Journal: BMC microbiology	Publication Date: Sep 10, 2018
Citations: 4	License type: open-access

Affiliation: Nanjing Agricultural University

Abstract

BackgroundDexamethasone (Dex), an artificially synthetic cortisol substitute, is commonly used as an anti-inflammatory drug, and is also employed to mimic the stress state experimentally. It is well known that chronic stress disturbs the gut microbiota community and digestive functions. However, no relevant studies have been conducted in ruminants.ResultsIn this study, a low dosage of Dex (0.2 mg/kg body weight, Dex group, n = 5) was consecutively injected intramuscularly for 21 days to simulate chronic stress in growing goats. Goats were injected with saline (0.2 mg/kg body weight) as the control group (Con, n = 5). Dex-treated goats showed a higher number of white blood cells and blood glucose levels (p < 0.01), but lower dry matter intake (DMI) and body weight (p < 0.01) than those of saline-injected goats. Plasma cortisol concentration decreased significantly in response to the Dex injection compared to the control (p < 0.05). The Dex treatment did not change most ruminal volatile fatty acid (VFAs) concentrations before the morning feeding after 1–21 days of treatment (p > 0.05); however, ruminal VFA concentrations decreased dramatically 2, 4, 6, and 8 h after the morning feeding on day 21 of the Dex injections. In this study, chronic Dex exposure did not alter the community structure of microbes or methanogenes in the rumen, caecum, or colonic digesta. Only Prevotella increased on days 7 and 14 of Dex treatment, but decreased on day 21, and Methanosphaera was the only genus of methanogene that decreased.ConclusionsOur results suggest that chronic Dex exposure retards growth by decreasing DMI, which may be mediated by higher levels of blood glucose and lower ruminal VFA production. Microbiota in the digestive tract was highly resistant to chronic Dex exposure.

Highlights

Dexamethasone (Dex), an artificially synthetic cortisol substitute, is commonly used as an anti-inflammatory drug, and is employed to mimic the stress state experimentally
The number of red blood cells increased markedly after 14 days of Dex treatment (p < 0.01), and showed a trend to increase on day 21 of Dex treatment compared to that in control goats (0.05 < p < 0.1) (Table 1)
As shown previously [24, 25], chronic Dex treatment significantly decreased dry matter intake (DMI) and body mass of growing goats, which may be attributable to the high level of blood glucose

Summary

Introduction

Dexamethasone (Dex), an artificially synthetic cortisol substitute, is commonly used as an anti-inflammatory drug, and is employed to mimic the stress state experimentally. It is well known that chronic stress disturbs the gut microbiota community and digestive functions. Cortisol is a stress hormone synthesized and released by the pituitary gland under stress conditions [1]. Stress induces metabolic disorders, such as diabetes and cardiovascular disease [2, 3]. A major mechanism by which cortisol regulates glucose metabolism is to inhibit insulin signaling, which promotes glucose transporter 4 expression on the cell surface [8, 9]. Microbiota play an important role in maintaining gut health and body homeostasis. Microbiota affect mucosal defense and inhibit the ability of enteric pathogens to colonize. Bäckhed et al and Ley et al reported that intestinal microbiota are associated with obesity and diabetes in germ-free mice [12, 13]. Many metabolites in the intestine are synthesized by microbes, such as vitamins K and B complex [14]

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