Hyperglycaemic effects of 5-hydroxytryptamine and dopamine in the freshwater prawn, Macrobrachium malcolmsonii.
The effects of 5-hydroxytryptamine (5-HT; serotonin) and dopamine (DA) on tissue carbohydrate metabolism and haemolymph glucose levels in the freshwater prawn, Macrobrachium malcolmsonii, were investigated. Injection of 5-HT and DA produced hyperglycaemia in a dose-dependent and time-dependent manner, with DA being more effective than 5-HT. Interestingly, 5-HT and DA induced hyperglycaemia only in intact prawns but not in bilaterally eyestalk-ablated individuals. Total carbohydrate (TCHO) and glycogen levels decreased and phosphorylase activity increased in the hepatopancreas and muscle of intact prawns after being injected with 5-HT or DA. However, bilateral eyestalk ablation decreased haemolymph glucose and tissue phosphorylase activity and increased TCHO and glycogen levels of the hepatopancreas and muscle. Injection of 5-HT or DA did not cause significant changes in these variables in eyestalk-ablated prawns. It is hypothesized that 5-HT and DA induce hyperglycaemia in prawns by stimulating the release of crustacean hyperglycaemic hormone (CHH) from the X-organ sinus gland (XO-SG) complex located in the eyestalk.
Komali
M
M
Department of Fishery Science and Aquaculture, Sri Venkateswara University, Tirupati, Andhra Pradesh 517 502, India.
Kalarani
V
V
Venkatrayulu
Ch
Ch
Chandra Sekhara Reddy
D
D
D000818:Animals; D060829:Arthropod Proteins; D001786:Blood Glucose / Q000187:drug effects*; D050260:Carbohydrate Metabolism; D004298:Dopamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D043143:Hepatopancreas / Q000378:metabolism; D007194:India; D007447:Invertebrate Hormones; D009132:Muscles / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D033541:Palaemonidae / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology*
D060829:Arthropod Proteins; D001786:Blood Glucose; D007447:Invertebrate Hormones; D009419:Nerve Tissue Proteins; C015947:hyperglycemic hormone, crustacean; D012701:Serotonin; D006005:Phosphorylases; D004298:Dopamine