Effects of recombinant growth hormone on growth factor and immune component levels in the cinnamon clownfish, Amphiprion melanopus

Abstract

We investigated the regulatory effects of recombinant growth hormone (rGH) on growth and immunity in an ornamental seawater fish species, the cinnamon clownfish (Amphiprion melanopus). Cinnamon clownfish received intraperitoneal injections of rGH or saline at doses of 0.1 or 1 µg/g, weekly, for 12 weeks. At the end of the experiment, the rGH injection group exhibited the greatest total length (5.3±0.3 and 5.6±0.2 cm, respectively, for the two doses). Moreover, after injection of rGH, the expression levels of pituitary GH mRNA and liver insulin-like growth factor I (IGF-I) mRNA increased significantly (by 18.9-fold and 5.7-fold, respectively), as assessed by quantitative real-time polymerase chain reaction, while the splenic levels of immunoglobulin M protein increased significantly (by 10.5-fold) as assessed by Western blot analysis. Plasma lysozyme and melatonin levels also increased by 2.1- and 1.37-fold, respectively, over those of the control group. Plasma alanine and aspartate aminotransferase levels at 12 weeks (764±46.4 and 3002±101.2 IU/l, respectively) were significantly higher than those at baseline; however, treatment with rGH decreased these values at 12 weeks (276±30.4 and 600.5±59.2 IU/l, respectively). These findings support the hypothesis that rGH plays important roles in the regulation of the GH–IGF-I axis for growth and immunity in the cinnamon clownfish.

Key words:

• Cinnamon clownfish
• recombinant growth hormone
• insulin-like growth factor I
• immunoglobulin M
• melatonin

Acknowledgements

This research was supported by the MSIP (Ministry of Science, ICT & Future Planning), Korea, under the ITRC (Information Technology Research Center) support programme supervised by the NIPA (National IT Industry Promotion Agency) (NIPA-2013-H0301-13-2009), and by the Fishery Commercialization Technology Development Program, Ministry for Food, Agriculture, Forestry and Fisheries, Korea.

Editorial responsibility: Göran Nilsson