Effects of Ammonia and Nitrite Stress on Immune and Metabolic Responses of Japanese Sea Bass, Lateolabrax Japonicus

Abstract

We investigated the effects of ammonia and nitrite stress on genes involved in metabolism and disease resistance in Japanese sea bass (_Lateolabrax japonicus_). Fish were exposed to pure seawater (control), 65.4 mg/L NH4+ -N, or 60.9 mg/L NO2--N for 7 days. Muscle, head-kidney, gill, spleen, and liver tissues were sampled regularly and the expression of immune and metabolism-related genes was monitored. The results indicated that the expression of immune-related genes such as heat shock proteins 70 and 90 were upregulated in the head-kidney, spleen, gill, liver, and muscle tissues under ammonia and nitrite stress. Glutamine synthetase (GS) expression increased to different degrees under ammonia and nitrite stress, while glutamate dehydrogenase (GDH) in the stress group upregulated in the gills. The expression of carbonic anhydrase (CA) was upregulated in the spleen and gill tissue under ammonia or nitrite stress. Expression of leptin (LEP) was upregulated in the muscle, gills and liver under nitrite stress; under ammonia stress, LEP expression did not fluctuate significantly in the spleen or gill. Insulin-like growth factor-1 (IGF-1) was downregulated in the spleen, while did not fluctuate obviously in the muscle and head-kidney under ammonia stress. These results indicate that ammonia and nitrite stress led to an upregulated immune related indexes response and increased metabolic activities in _L. japonicus_, and provides reference suggestions for response status of these health markers answering the outside environment intimidation.