Abstract
Endogenous microbiota play essential roles in the host’s immune system, physiology, reproduction and nutrient metabolism. We hypothesized that a continuous administration of an exogenous probiotic might also influence the host’s development. Thus, we treated zebrafish from birth to sexual maturation (2-months treatment) with Lactobacillus rhamnosus, a probiotic species intended for human use. We monitored for the presence of L. rhamnosus during the entire treatment. Zebrafish at 6 days post fertilization (dpf) exhibited elevated gene expression levels for Insulin-like growth factors -I and -II, Peroxisome proliferator activated receptors -α and -β, VDR-α and RAR-γ when compared to untreated-10 days old zebrafish. Using a gonadotropin-releasing hormone 3 GFP transgenic zebrafish (GnRH3-GFP), higher GnRH3 expression was found at 6, 8 and 10 dpf upon L. rhamnosus treatment. The same larvae exhibited earlier backbone calcification and gonad maturation. Noteworthy in the gonad development was the presence of first testes differentiation at 3 weeks post fertilization in the treated zebrafish population -which normally occurs at 8 weeks- and a dramatic sex ratio modulation (93% females, 7% males in control vs. 55% females, 45% males in the treated group). We infer that administration of L. rhamnosus stimulated the IGF system, leading to a faster backbone calcification. Moreover we hypothesize a role for administration of L. rhamnosus on GnRH3 modulation during early larval development, which in turn affects gonadal development and sex differentiation. These findings suggest a significant role of the microbiota composition on the host organism development profile and open new perspectives in the study of probiotics usage and application.
Highlights
The group of Lactic acid bacteria (LAB) represents a large part of the microbiota of vertebrates [1] and their beneficial effects on the immune system [2,3,4], gastrointestinal tract [5], and reproduction [6,7] have been widely reported
No significant difference was observed at 6 dpf for dry weight and total length, while a higher wet weight was found in probiotic fed larvae body weight and total length
Stress Biomarkers Concerning glucocorticoid receptor (GR) gene expression (Figure 2A), no significant differences were evaluated among the different developmental stages in the control; in the probiotic group, significantly lower gene expression levels were observed at 6, 10 and 20 dpf
Summary
The group of Lactic acid bacteria (LAB) represents a large part of the microbiota of vertebrates [1] and their beneficial effects on the immune system [2,3,4], gastrointestinal tract [5], and reproduction [6,7] have been widely reported. We speculated that different microbiota compositions might correspond to different physiological and developmental performances; in the current study we wondered what effects we could induce in the developmental profile of the host organism if we influenced the gut microbiota from birth to puberty by providing a selected LAB strain. The LAB strain we selected was Lactobacillus rhamnosus, which is one of the main components of the commensal microflora of human intestinal tract of and is widely used as a probiotic in mammals [13,14,15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
