Serotonergic regulation of blood glucose levels in the crayfish,Procambarus clarkii: Site of action and receptor characterization

Abstract

The present study investigated the site of action of 5‐hydroxytryptamine (5‐HT) and pharmacologically characterized the receptors involved in regulating blood glucose levels in the crayfish, Procambarus clarkii. Injection of 5‐HT into intact animals increased glucose levels in a dose‐dependent manner. In contrast, 5‐HT failed to elicit a hyperglycemic response in eyestalk‐ablated animals. Effects of several 5‐HT receptor agonists and antagonists were examined. 5‐CT, oxymetazoline (both 5‐HT1 receptor agonists) and α‐methyl‐5‐HT (a 5‐HT2 receptor agonist), but not 1‐phenylbiguanide, m‐CPBG (both 5‐HT3 receptor agonists), or RS 67333 (a 5‐HT4 receptor agonist), induced hyperglycemic responses in a dose‐dependent manner. In addition, 8‐OH‐DPAT (a 5‐HT1A receptor agonist), L‐694,247 (a 5‐HT1B/1D receptor agonist), and DOI (a 5‐HT2A receptor agonist) were effective in significantly increasing the glucose levels, whereas both BW 723C86 (a 5‐HT2B receptor agonist) and m‐CPP (a 5‐HT2C receptor agonist) were ineffective. Finally, ketanserin (a 5‐HT2A receptor antagonist), but not p‐MPPF (a 5‐HT1A receptor antagonist), GR 55562 (a 5‐HT1B/1D receptor antagonist), SB 206553 (a 5‐HT2B/2C receptor antagonist), or tropisetron (a 5‐HT3 receptor antagonist), was able to block 5‐HT‐induced hyperglycemia. The combined results support the hypothesis that 5‐HT exerts its hyperglycemic effect by enhancing the release of hyperglycemic factor(s) from the eyestalks, and suggest that 5 HT‐induced hyperglycemia is mediated by 5‐HT1‐ and 5‐HT2‐like receptors. J. Exp. Zool. 286:596–605, 2000. © 2000 Wiley‐Liss, Inc.

Organization and expression study of the shrimp (Metapenaeus ensis) putative 5-HT receptor: Up-regulation in the brain by 5-HT

“…In crayfish and lobster, 5-HT modulates the escape and aggressive behaviors in laboratory conditions (Kravitz, 2000;Huber et al, 1997). It also modulates retinal sensitivity in crayfish (Arcehiga et al, 1990) and stimulates the increase of hemolymph glucose concentration in different crustaceans (Luschen et al, 1993;Lee et al, 2001Lee et al, , 2000. Moreover, 5-HT also enhanced the darkening of crayfish by the release of pigment-dispersing hormone (Fingerman et al, 1994), stimulated the molting event (Mattson and Spaziani, 1985), and stimulated rapid gonad maturation (Vaca and Alfaro, 2000).…”

Conservation of structure, signaling and pharmacology between two serotonin receptor subtypes from decapod crustaceans, Panulirus interruptus and Procambarus clarkii

“…Because posture is an essential component of agonistic behavior, these receptors may therefore contribute to different aspects of the agonistic behavioral program (Edwards and Kravitz, 1997;Huber et al, 1997;Kravitz, 2000). Although 5-HT 1␣Pro is expressed by neurons throughout the crayfish eyestalk (Spitzer et al, 2005), it may not mediate 5-HT-elicited hyperglycemia as this was not mimicked by mCPP (Lee et al, 2000). 5-HT 2␤Pro may, however, be involved as the response was evoked by both 5-CT and 8-OH-DPAT.…”

Serotonin, but not dopamine, controls stress response and anxiety-like behavior in crayfish, Procambarus clarkii.

“…These peptidic hormones, produced in the X-organ and released from the sinus gland of eyestalks, control the stress response in peripheral organs, particularly leading to energy mobilization by an increase in blood glucose (reviewed by Fingerman, 1997;Fanjul-Moles, 2006). Moreover, the link between 5-HT and glucose has been previously highlighted using 5-HT antagonists, which are able to block the increase in glucose concentrations in crayfish (Lee et al, 2000). Various stressors elicit the release of CHHs and the subsequent increase in blood glucose in crustaceans, such as hypoxia and emersion, disease, thermal stress, heavy metals exposure or social interactions (Webster, 1996;Chang et al, 1998;Stentiford et al, 2001;Wilcockson et al, 2002;Lorenzon et al, 2004;Elwood, 2011;Aquiloni et al, 2012).…”