The acute modulation of norepinephrine on immune responses and genes expressions via adrenergic receptors in the giant freshwater prawn, Macrobrachium rosenbergii

Norepinephrine (NE), immunocompetent parameters (total haemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB), superoxide dismutase (SOD) activity, phagocytic activity and clearance efficiency to Lactococcus garvieae), and prophenoloxidase (proPO) system-related genes (lipopolysaccharide- and beta-1,3-glucan-binding protein, LGBP; prophenoloxidase, proPO; peroxinectin, PE; alpha 2-macroglobulin, alpha 2-M) expressions were investigated in Macrobrachium rosenbergii received NE through injection at 50 pmol/prawn after 0, 30, 60, and 120 min. Furthermore, the PO activity, RB, SOD activity, phagocytic activity and proPO system-related genes expressions were determined in haemocytes incubated with cacodylate buffer (CAC), NE, and NE co-treated with various adrenergic receptor (AR) antagonists in vitro. Results showed that NE, THC, granular cells, PO activity, SOD activity, proPO system-related genes expressions, and phagocytic activity and clearance efficiency to L. garvieae increased; PO activity per granulocyte and RB per haemocyte decreased from 30 to 120 min; semigranular cells and RB increased in the initial 30 min, and then decreased at 120 min when the prawns received NE by injection. In vitro studies, all the determined immune parameters and genes expressions were significantly decreased in haemocytes incubated with NE after 30 min. The negative effects of NE were prevented on the PO activity and phagocytic activity by the beta-AR antagonist of metoprolol (Met), on the SOD activity by the beta-AR antagonist of propranolol (Pro), on the RB by the beta-AR antagonist of Met and prazosin (Pra), and on the proPO system-related genes expressions by alpha-AR antagonist of Pra. These results show that NE modulates prawn haemocytes proPO system-related genes expressions via alpha 1-AR, PO activity and phagocytosis via beta 1-AR, respiratory burst via alpha 1-and beta 1-ARs, and SOD activity via beta 2-AR. It is concluded that NE stimulates the regulation of immunocompetence parameters and proPO system-related, genes expressions in an acute response to maintain homeostasis of M. rosenbergii, which is primarily mediated through alpha 1-, beta 1-and beta 2-ARs. (C) 2015 Elsevier Ltd. All rights reserved.