Pavlova, I. & A. Milanova, 2017.

Different effect of doxycycline and enrofloxacin on cathelicidin-3 mRNA expression in chickens with or without probiotics supplementation.

Bulg. J. Vet. Med., 20, No 4, 357–366.    DOI: 10.15547/bjvm.1026

The function of immune system of poultry has a significant impact on poultry husbandry sustainabi­lity. Therefore the aim of this study was to investigate the effect of lactic acid bacteria administered with enrofloxacin or doxycycline on expression levels of antimicrobial peptide cathelicidin-3 (CATH3) at mRNA level in the duodenum, jejunum and liver of broilers. A day-old Ross (n=24) and Duc (n=24) chickens were included in experiments with enrofloxacin and doxycycline, respectively. They were divided into four groups (n=6) for each experiment: control, supplemented with probiotics (15 days via feed, 5 days after hatching), treated with either enrofloxacin or doxycycline (10 mg.kg^-1 for 5 days, via drinking water) and treated with antibiotic and probiotics. Expression levels of CATH3 mRNA in liver, duodenum and jejunum were determined by RT-PCR and were statistically evaluated by Mann-Whitney test.Administration of probiotics led to insignificant down-regulation of CATH3 mRNA in the investigated tissues. The combination of doxycycline with probiotics led to statistically significant down-regulation of CATH3 mRNA in the duodenum (P<0.01). Statistically significant up-regulation of mRNA of the studied gene was found in the jejunum of enrofloxacin treated Ross chickens. The data suggest the existence of an interaction between antibiotics and innate immunity. Further evaluation in infected poultry would shed more light on the pharmacodynamics of antibacterials.

Key words: CATH3 mRNA, doxycycline, Duc and Ross broilers, enrofloxacin, Lactobacillus spp.