Prevention of Heat Stress Adverse Effects in Rats by Bacillus subtilis Strain

Summary

We described a protocol for prevention of heat stress effects in rats by oral pre-treatment with beneficial bacteria. This protocol can be modified and used for various routes of administration and for analysis of different compounds.

Abstract

This study was designed to evaluate the protective effect of the Bacillus subtilis strain against complications related to heat stress. Thirty-two Sprague-Dawley rats were used in this study. Animals were orally treated twice a day for two days with B. subtilis BSB3 strain or PBS. The next day after the last treatment, each group was divided and two experimental groups (one treated with PBS and one treated with B. subtilis) were placed at 45 ^oC for 25 min. Two control groups stayed for 25 min at room temperature. All rats were euthanized and different parameters were analyzed in all groups. Adverse effects of heat stress are registered by the decrease of villi height and total mucosal thickness in the intestinal epithelium; translocation of bacteria from the lumen; increased vesiculation of erythrocytes and elevation of the lipopolysaccharides (LPS) level in the blood. The protective efficacy of treatment is evaluated by prevention of these side effects. The protocol was set up for the oral treatment of rats with bacteria for prevention of heat stress complications, but this protocol can be modified and used for other routes of administration and for analysis of different compounds.

Introduction

Different stressors affect human and animal health. Temperature is one of the most stressful factors, causing chronic, acute and even lethal illnesses¹. Changes in intestinal morphology and a loss of gut barrier integrity after heat stress were documented in many cases^2,3. This protective barrier is responsible for defense against translocation of gut bacteria and their toxins, in particular lipopolysaccharides (LPS), from the lumen to the internal circulation^4,5. Stability of the gut microbiota significantly influences intestinal barrier function, the immune response of the host, and tolerance to stress conditions⁶. Thus, m....

Protocol

All experimental procedures were approved by IACUC of Auburn University, Auburn, Alabama.

1. Preparation of Culture Media, Dishes and Bacterial Culture

1. Inoculate 10 ml of nutrient broth in a flask with a single colony of Bacillus subtilis BSB3 culture, grown overnight on a nutrient agar plate.
2. Make 500 ml of sporulation medium¹⁹ (per liter: Bacto Nutrient Broth, 8 g; 10% (w/v) KCl, 10 ml; 1.2% (w/v) MgSO₄ x 7H₂O, 10 ml; agar, 15 g) and autoclave at 121 ^oC for 20 min. Allow to cool to 50 ^oC and add the following sterile solutions:1 M Ca(NO₃)₂, 1 ml; 0.01 M....

Results

The mean body temperature of animals before and immediately after heat stress was 36.7 ± 0.07 ^oC and 40.3 ± 0.17 ^oC, respectively (P < 0.05). Exposure of rats to heat (group 3) resulted in significant inhibition of villi height and total mucosal thickness (Figures 2, 3). Oral administration of BSB3 strain before stress protected intestine from the harmful effect of heat.

Translocation of.......

Discussion

Exposure to high temperature results in serious health conditions²⁹. Prevention and early detection of complications related to heat stress are of vital importance³⁰. The presented protocol can be used to evaluate the efficacy of various approaches for the prevention of heat stress adverse effects.

Critical steps within this protocol include: the heat treatment procedure (45 ^oC, 25 min); the usage of apyrogenic materials during collection and p.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Phosphate buffered saline (PBS)	Sigma-Aldrich, St. Louis, MO	P4417
Ethyl Alcohol	Pharmco products Inc. Brookfield, CT, USA	64-17-5
Agar	VWR	97064-334
MacConkey agar plates	VWR	470180-742
5% blood agar plates	VWR	89405-024
Brucella blood agar plate with Hemin, and Vitamin K	VWR	89405-032
Bouin’s Fixative	Electron Microscopy Sciences, Hatfield, PA, USA	15990
IL-10 Rat ELISA kit	Invitrogen, Camarillo, CA, USA	KRC0101
IL-1beta Rat ELISA Kit	Invitrogen, Camarillo, CA, USA	KRC0011
IL-6 Rat ELISA Kit	Invitrogen, Camarillo, CA, USA	KRC0061
INF-gamma Rat ELISA Kit	Invitrogen, Camarillo, CA, USA	KRC4021
TNF-alpha Rat ELISA Kit	Invitrogen, Camarillo, CA, USA	KRC3011
Rat LPS ELISA Kit	NeoBioLab, MA, USA	RL0275
Environmental Chamber 6020-1	Caron, Marietta, OH, USA	6020-1
Centrifuge	Beckman Coulter, Indianapolis, IN, USA	Optima L-90K
Ultra Centrifuge
Light microscope optical system	CitoViva Technology Inc., Auburn, AL
Colony counter	Fisher Scientific , Pittsburgh, PA, USA	RE-3325
Freezer	Haier, Brooklyn, NY, USA	HCMO50LA
Ultra microplate reader	Bio-Tek Instrument, Winooski, VT, USA	ELx 808
Auto Strip Washer	Bio-Tek Instrument, Winooski, VT, USA	ELx50
Pipettes	Gilson, Pipetman, France	P100, P200, P1000
C24 Incubator Shaker	New Brunswick Scientific, Enfield, CT, USA	Classic C24
Rocking Shaker	Reliable Scientific, Inc., Nesbit, MS, USA	55
Petri dishes	Fisher Scientific, Pittsburgh, PA, USA	875713	100 mm x 15 mm
SterilGard III Advance	The Baker Company, Sanford, ME, USA	SG403
Culture Growing Flasks	Corning Incorporated, Corning, NY, USA	4995	PYREX 250 ml Erlenmeyer flasks
Optical Spectrometer Genesys 20	Thermo Scientific, Waltham, MA, USA.	4001
Sony DXC-33 Video camera	Sony
Richardson test slide	Electron Microscopy Science, Hatfield, PA, USA	80303
Millipore water purification system	Millipore	Direct-Q
Image-Pro Plus software	Media Cybernetics, MD, USA
Triple Beam Balance	OHAUS Corporation, Parsippany, NJ, USA
Tissue Homogenizer, Dounce	VWR	71000-518