The Hyperglycemic Effect of Melatonin in the Chinese Mitten Crab, Eriocheir sinensis

Abstract

Melatonin has been identified in a variety of invertebrate species, but its function is not as well understood as in crustaceans. The effects of melatonin on hemolymph glucose levels and tissue carbohydrate metabolism in the Chinese mitten crab, Eriocheir sinensis, were fully investigated in this study. Moreover, whether the eyestalk (an important endocrine center in invertebrate species) involves in this process or not, also were clarified. Analysis revealed that eyestalk ablation, especially bilateral, caused a significant decrease in the hemolymph glucose level. Moreover, injection of melatonin induced hyperglycemia in a dose-dependent manner both in intact and ablated crabs. Based on the expression of CHH mRNA in the 10 different tissues, eyestalk, thoracic ganglion, intestinal tract and hemolymph were selected to estimate the effect of melatonin on the expression of CHH mRNA. Bilateral eyestalk ablation caused a significant increase in the expression of CHH mRNA in the thoracic ganglion, intestinal tract and hemolymph compared with the controls. In addition, injection of melatonin into intact or ablated crabs elevated the CHH mRNA level in the eyestalk, thoracic ganglion and intestinal tract tissues compared with controls. The hemolymph CHH mRNA after melatonin injection was elevated only in ablated crabs. Administration of melatonin resulted in a significant decrease in total carbohydrates and glycogen levels with an increase in phosphorylase activity levels in the hepatopancreas and muscle in intact and ablated crabs. Our findings demonstrated that melatonin can induce hyperglycemic effects in both intact and ablated crabs, suggesting that this effect is probably not mediated solely via eyestalk.

5-HT2B, 5-HT7, and DA2 Receptors Mediate the Effects of 5-HT and DA on Agonistic Behavior of the Chinese Mitten Crab (Eriocheir sinensis)

“…The 10 –6 , 10 –8 , and 10 –10 mol/crab 5-HT injection groups were named as 10 –6 , 10 –8 , and 10 –10 mol 5-HT, respectively. The 10 –6 , 10 –8 , and 10 –10 mol/crab DA injection groups were named as 10 –6 , 10 –8 , and 10 –10 mol DA, respectively. , Each crab was injected in the third pereiopod with 20 μL of crustacean saline, which contained the drugs . According to reports, injected 5-HT is rapidly distributed throughout the hemolymph, and most (75%) is cleared from the hemolymph via tissue uptake and/or binding within 5 min after injection in crayfish .…”

“…39,53 Each crab was injected in the third pereiopod with 20 μL of crustacean saline, which contained the drugs. 54 According to reports, injected 5-HT is rapidly distributed throughout the hemolymph, and most (75%) is cleared from the hemolymph via tissue uptake and/or binding within 5 min after injection in crayfish. 11 Based that study, after drug injection, the crabs were placed in water for 10 min, and crabs that were injected with the same dose of a drug were used to observe agonistic behavior according to the description in the section "Pairing".…”

Comparative metabolomic analysis of Chinese mitten crab (Eriocheir sinensis) during the daily cycle

“…Melatonin can affect the physiological functions of the hepatopancreas in crustaceans. For instance, melatonin affects blood glucose in crustaceans (Yang et al, 2018); the secretion of melatonin can also promote digestive enzyme function (Cong et al, 2018) and immunity (Balzer et al, 2012). Based on these correlations, we suggest that the circadian rhythms of hepatopancreas metabolites and their physiological functions in E .…”

CasEcR and CasMIH Genes in the Blue Crab, Callinectes sapidus: A Temporal Evaluation and Melatonin Effects

“…As to melatonin actions in crustaceans, it has already been demonstrated that the indoleamine plays a role in limb regeneration ( Tilden et al, 1997 ), ecdysteroid production ( Sainath S. B. and Reddy P. S., 2010 ; Girish et al, 2015 ), antioxidant defense ( Maciel et al, 2010 ; Geihs et al, 2016 ; She et al, 2019 ), color change ( Nery et al, 1999 ), locomotor activity ( Geihs et al, 2010 ), and hyperglycemia ( Sainath SB. and Reddy PS., 2010 ; Maciel et al, 2014 ; Yang et al, 2018 ), among others. Many melatonin functions in crustaceans are related to the molt cycle, as shown by the increased levels of ecdysteroids in melatonin-treated Y-organ cells ( Girish et al, 2015 ).…”