ABSTRACT
Title
Social behavior and fear response to predator in zebrafish: Role of oxytocin/vasopressin system
Authors
R. Martucci
Graduate School in Pharmacological Sciences
Dept. of Pharmacology, Chemotherapy and medical Toxicology,
Università degli Studi di Milano, Italy
Graduate School in Pharmacological Sciences
Dept. of Pharmacology, Chemotherapy and medical Toxicology,
Università degli Studi di Milano, Italy
Abstract
Zebrafish (Danio rerio) is an emerging animal model for studying human diseases, brain development and function (1). Its typical shoaling behavior (tight aggregation of individuals)consisting of forming a tight group in which fish swim together, may represent an excellent model to study social behavior. The neuropeptides oxytocin (OT) and arginine vasopressin (AVP) are two of the most-studied brain signaling molecules encoding information relevant to social behavior. Isotocin (IT) and vasotocin (AVT) are the equivalent neurohypophysial hormones in fish regulating reproductive and social behavior (2). However, no data are available about the effect of these neuropeptides on zebrafish.
Based on this, our goal was to study the effct of both OT and AVP on shoaling behavior, in comparison with IT and AVT. Since these peptides are known to affect anxiety in humans and rodents (3), the same compounds were also tested on fear response to predator.
Preferenceto shoal with conspecific (wild-type) or with mutant zebrafish (lacking of melanophore stripes) was evaluated by placing each individual subject fish in a tank divided in three compartments containing separate wild-type and nacre stimulus shoals. The time spent swimming near each shoal by subject stimulus was recorded (4). Fear response to predator (5) was tested by placing for 10 min each individual subject fish in a test tank containing in a separate side the stimulus fish (Astronotus Ocellatus) and in the other only water. OT (0.2-30 ng/kg) , AVP (0.1-30 ng/kg), IT and AVT (0.1-1 ng/kg) were given i.m. 10 min before each test.
To investigate the mechanism of action different antagonists were given 10 min before each peptide: the OT receptor antagonist (DesGly–NH2-d(CH2)5-[D-Tyr2, Thr4] OVT) (desgly) the most selective analogue reported to date (95 times more potent as an OT than AVP receptor antagonist, in the rat (6); the V1a receptor subtype AVP antagonist ( (2S)-1-[[(2R,3S)-5-Chloro-3 (2- chlorophenyl)-1-[(3,4-dimethoxyphenyl)sulfonyl]-2,3-dihydro-3- hydroxy-1H-indol-2-yl]carbonyl]-2-pyrrolidinecarboxamide) (SR 49059) (7); the V1b receptor subtype antagonist (2S,4R)-1-[5-chloro-1-(2,4-dimethoxyphenyl) sulfonyl) -3-(2- methoxyphenyl) -2-oxo - 2,3 – dihydro - 1H – indol –3-yl] –4 -hydroxy-N, N-dimethyl-2-pyrrolidine carboxamide (SSR149415) (8).
In the shoaling and fear response to predator tasks, treatment with all the peptides increased social preference and decreased fear in a dose-dependent manner interpolated by symmetrical parabolas. The potency was: AVT>ISO>AVP>OT. Pre-treatment with SR49059, SSR149415 and desgly dose-dependently blocked the pro-social and anxiolytic effect induced by each peptide.
These findings show for the first time the pro-social and anxiolytic properties of OT/AVP system mediated by different receptors in zebrafish and open a new avenue of research for the development of new drugs to treat anxiety-related diseases or abnormal social behaviors including autism.
1) Gerlai R (2003)- Behav Genet vol 33:461–8.
2) Goodson JL, Bass AH -(2000)- Naturevol 403:769-772.
3) Young LJ (2009)- Naturevol 457:148.
4) Engeszer et al(2004)- Current Biology vol 14:881–884.
5) Bass SL , Gerlai R (2008)- Behav Brain Res vol 186:107-117.
6) Manning et al (1995)- Int J Peptide Protein Res vol 46:244-252;
7) Serradeil-Le Gal et al (1994)- Biochem Pharmacol vol 47:633-41;
8) Serradeil-Le Gal et al (2007)- Am J Physiol Regul Integr Comp Physiol vol 293:R938-49
Based on this, our goal was to study the effct of both OT and AVP on shoaling behavior, in comparison with IT and AVT. Since these peptides are known to affect anxiety in humans and rodents (3), the same compounds were also tested on fear response to predator.
Preferenceto shoal with conspecific (wild-type) or with mutant zebrafish (lacking of melanophore stripes) was evaluated by placing each individual subject fish in a tank divided in three compartments containing separate wild-type and nacre stimulus shoals. The time spent swimming near each shoal by subject stimulus was recorded (4). Fear response to predator (5) was tested by placing for 10 min each individual subject fish in a test tank containing in a separate side the stimulus fish (Astronotus Ocellatus) and in the other only water. OT (0.2-30 ng/kg) , AVP (0.1-30 ng/kg), IT and AVT (0.1-1 ng/kg) were given i.m. 10 min before each test.
To investigate the mechanism of action different antagonists were given 10 min before each peptide: the OT receptor antagonist (DesGly–NH2-d(CH2)5-[D-Tyr2, Thr4] OVT) (desgly) the most selective analogue reported to date (95 times more potent as an OT than AVP receptor antagonist, in the rat (6); the V1a receptor subtype AVP antagonist ( (2S)-1-[[(2R,3S)-5-Chloro-3 (2- chlorophenyl)-1-[(3,4-dimethoxyphenyl)sulfonyl]-2,3-dihydro-3- hydroxy-1H-indol-2-yl]carbonyl]-2-pyrrolidinecarboxamide) (SR 49059) (7); the V1b receptor subtype antagonist (2S,4R)-1-[5-chloro-1-(2,4-dimethoxyphenyl) sulfonyl) -3-(2- methoxyphenyl) -2-oxo - 2,3 – dihydro - 1H – indol –3-yl] –4 -hydroxy-N, N-dimethyl-2-pyrrolidine carboxamide (SSR149415) (8).
In the shoaling and fear response to predator tasks, treatment with all the peptides increased social preference and decreased fear in a dose-dependent manner interpolated by symmetrical parabolas. The potency was: AVT>ISO>AVP>OT. Pre-treatment with SR49059, SSR149415 and desgly dose-dependently blocked the pro-social and anxiolytic effect induced by each peptide.
These findings show for the first time the pro-social and anxiolytic properties of OT/AVP system mediated by different receptors in zebrafish and open a new avenue of research for the development of new drugs to treat anxiety-related diseases or abnormal social behaviors including autism.
1) Gerlai R (2003)- Behav Genet vol 33:461–8.
2) Goodson JL, Bass AH -(2000)- Naturevol 403:769-772.
3) Young LJ (2009)- Naturevol 457:148.
4) Engeszer et al(2004)- Current Biology vol 14:881–884.
5) Bass SL , Gerlai R (2008)- Behav Brain Res vol 186:107-117.
6) Manning et al (1995)- Int J Peptide Protein Res vol 46:244-252;
7) Serradeil-Le Gal et al (1994)- Biochem Pharmacol vol 47:633-41;
8) Serradeil-Le Gal et al (2007)- Am J Physiol Regul Integr Comp Physiol vol 293:R938-49