The organization of the histaminergic system in adult zebrafish (Danio rerio) brain: neuron number, location and co-transmitters
- Authors
- Sundvik, M., and Panula, P.
- ID
- ZDB-PUB-120424-28
- Date
- 2012
- Source
- The Journal of comparative neurology 520(17): 3827-3845 (Journal)
- Registered Authors
- Panula, Pertti, Sundvik, Maria
- Keywords
- hsitamine, thyrotropin-releasing hormone, galanin, γ-aminobutyric acid, methionine-enkephalin, hypothalamus
- MeSH Terms
-
- Animals
- Arousal/physiology
- Behavior, Animal/physiology*
- Brain/cytology
- Brain/metabolism*
- Female
- Histamine/analysis
- Histamine/biosynthesis*
- Immunohistochemistry
- Male
- Neurons/metabolism*
- Neurons/ultrastructure
- Neurotransmitter Agents/analysis
- Neurotransmitter Agents/biosynthesis*
- Zebrafish
- PubMed
- 22522821 Full text @ J. Comp. Neurol.
Histamine is an essential factor in the ascending arousal system (AAS) during motivated behaviors. Histamine and hypocretin/orexin (hcrt) are proposed to be responsible for different aspects of arousal and wakefulness, histamine mainly for cognitive and motivated behaviors. We have in this study visualized the entire histaminergic neuron population in adult male and female zebrafish brain and quantified the histaminergic neuron numbers. There were 40-45 histaminergic neurons in both male and female zebrafish brain. Further, we identified co-transmitters of histaminergic neurons in the ventrocaudal hypothalamus, i.e. around the posterior recess (PR) in adult zebrafish. Galanin, γ-aminobutyric acid (GABA) and thyrotropin-releasing hormone (TRH) were co-localized with histamine in some but not all neurons, a result that was verified by intracerebroventricular (i.c.v.) injections of colchicine into adult zebrafish. Fibers immunoreactive (ir) for galanin, GABA, TRH or methionine-enkephalin (mENK) were dense in the ventrocaudal hypothalamus around the histaminergic neurons. In histamine-ir fibers TRH and galanin immunoreactivities were also detected in the ventral telencephalon. All these neurotransmitters are involved in maintaining the equilibrium of sleep-wake state. Our results are in accordance with results from rats, further supporting the use of zebrafish as a tool to study molecular mechanisms underlying complex behaviors.