Can Probiotics Affect Reproductive Processes of Aquatic Animals? - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 341

12.6 CONCLUDING REMARKS
It is evident from the available literature that positive effects on fish reproduction can be
achieved with dietary probiotic administration, although the mechanisms through which probi-
otics may enhance reproduction are only partly described. A possible explanation of the effects
of Lb. rhamnosus on zebrafish reproduction is reported in recent works in which PCR-DGGE
analysis revealed that the probiotic was not directly associated with ovaries, excluding its pos-
sible locally direct role (Gioacchini et al. 2012). In addition, the same authors showed that at
both gut and brain levels the probiotic treatment induced a significant increase in leptin gene
expression, a key hormone in energy homeostasis and neuroendocrine functions. In the same
study, this increase was correlated with a significant rise of KiSS1, KiSS2 and gnrh3 gene
expression in the brain. These results could suggest that the probiotic may act indirectly by
activating a potent metabolic hormone such as leptin, and that this hormone (alone or with
other hormones) may represent the link between metabolic and reproductive systems, through
which the probiotic may act.
At present no studies have been conducted on a large scale on marine commercial species
affected by reproductive dysfunctions. The results achieved in freshwater species provide a
foundation for future studies to progress to experimentation directly conducted in an indus-
trial scale hatchery system with commercially important marine species. Furthermore research
should also focus on studying the probiotic effects on male fish reproductive performance and
gonadal development.
The significance of the results available today underlines the importance of gut microbes
in reproductive processes, supporting the potentiality of feed additives such as probiotics, fre-
quently used in aquaculture practices, as a new technology to improve reproduction.
12.7 ACKNOWLEDGEMENTS
The authors wish to thank all their colleagues from the Department of Life and Environment
Science, Università Politecnica delle Marche, from the Biomedical Genomics laboratory (BIO-
GEM), University of California San Diego, from SISSI beamline, ELETTRA Synchrotron
Light Laboratory, from the Aquaculture and Fish Nutrition Research Group, School of Bio-
logical Sciences, Plymouth University and from Synbiotec Srl for their help.
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