Evidence for the Involvement of the Crustacean Hyperglycemic Hormone in the Regulation of Lipid Metabolism

Abstract

Effects of the crustacean hyperglycemic hormone on total lipids in the hemolymph of Chasmagnathus granulata and on free fatty acids, phospholipids, and triglycerides in the hemolymph of Carcinus maenas, as well as on their release by Orconectes limosus hepatopancreas in vitro, were investigated. Eyestalk ablation led to a significant decrease of total lipids in the hemolymph of C. granulata and of free fatty acid levels in C. maenas. Crustacean hyperglycemic hormone injections completely reversed the effects of eyestalk extirpation in short-term experiments. Crustacean hyperglycemic hormone also caused significant elevations of hemolymph phospholipids and triglycerides in eyestalkless C. maenas. The release of free fatty acids and phospholipids from O. limosus hepatopancreas in vitro was significantly increased in the presence of crustacean hyperglycemic hormone. These results suggest a physiological role for crustacean hyperglycemic hormone in the control of lipid metabolism in crustaceans. This role may be similar to that of the adipokinetic hormone of insects.

The adaptive significance of crustacean hyperglycaemic hormone (CHH) in daily and seasonal migratory activities of the Christmas Island red crab Gecarcoidea natalis

“…This is exemplified by Basu and Kravitz (Basu and Kravitz, 2003) who have shown, using a combination of immunohistochemistry and electrophysiological techniques, that the neurotransmitters octopamine and serotonin inhibit spontaneous bursting of CHH immunoreactive neurones in the second thoracic nerve roots of Homarus americanus. In view of previous work either supporting the idea that CHH levels might be controlled via feedback mechanisms involving metabolites such as glucose (Santos and Keller, 1993;Glowik et al, 1997), or proposing the involvement of CHH in lipid metabolism following the observation that CHH injection elevates haemolymph phospholipids and triglycerides in Carcinus maenas (Santos et al, 1997), experiments were designed in which various compounds (glucose, lactate, phospholipids, amino acids) were repeatedly injected over several days to raise their concentration in the haemolymph. Subsequently, crabs were exercised and their CHHrelease response measured.…”

“…CHH release from the sinus gland results in hyperglycaemia due to the inhibition of glycogen synthase in the midgut gland and muscle (Sedlmeier, 1985). However, it is now widely appreciated that these hormones are pleiotropic; related biological functions include secretagogue activity (Sedlmeier, 1988) and lipid mobilisation (Santos et al, 1997), and a plethora of functions unrelated to regulation of energy mobilisation have now been discovered. These include the repression of ecdysteroid synthesis by the Y-organ, and thus a possible involvement in moult control (Webster and Keller, 1986;Chang et al, 1990), the inhibition of reproductive processes via the inhibition of methyl farnesoate synthesis (Liu et al, 1997), and the inhibition of vitellogenin (Vg) mRNA, protein synthesis (Khayat et al, 1998) or Vg gene expression (Tsutsui et al, 2005).…”

Respuestas fisiológicas de Neotrypaea uncinata (Decapoda: Thalassinidea) a la hipoxia y al parasitismo por Ionella agassizi (Isopoda: Epicaridea)

“…45, Nº3, 2010 Revista de Biología Marina y Oceanografía tiempo (Santos & Keller 1993, Santos et al 1997. Este tipo de respuesta corresponde a una medida compensatoria frente a la elevada actividad energética que genera el estrés en un organismo, especialmente en crustáceos.…”

Cloning of Two Crustacean Hyperglycemic Hormone Isoforms in Freshwater Giant Prawn ( Macrobrachium rosenbergii ): Evidence of Alternative Splicing

“…Injection of the eyestalk extract or purified CHH will remedy hypoglycemia in eyestalkless individuals by regulating phosphorylase and glycogen synthase activities on the target tissues, as well as amylase secretion of the midgut gland (Sedlmeier, 1982;Keller and Sedlmeier, 1988). CHH is released in response to internal signals, such as the circadian rhythmicity of hemolymph glucose content (Kallen et al, 1990;Santos and Keller, 1993b), or to external stimuli, such as hypoxia (Santos and Keller, 1993a;Webster, 1996), parasite infection (Stentiford et al, 2001), thermal shock (Santos et al, 1997;Kuo and Yang, 1999), and pollutants (Reddy et al, 1994(Reddy et al, , 1996Lorenzon et al, 1997Lorenzon et al, , 2000. In addition to carbohydrate metabolism, CHH was proved to be involved in lipid metabolism in Chasmagnathus granulata, Carcinus maenas, and Orconectes limosus (Santos et al, 1997).…”