|ZFIN ID: ZDB-PUB-121227-4|
|Source:||Journal of molecular endocrinology 50(2): 115-129 (Journal)|
|Registered Authors:||Rodriguez, Raquel E.|
|PubMed:||23256992 Full text @ J. Mol. Endocrinol.|
Opioid and tachykinins receptors (TACRs) are closely related in addiction and pain processes. In zebrafish, opioid receptors have been cloned and characterized both biochemically and pharmacologically. However, TACR1 gene has not yet been described in zebrafish. The aim of this research was to identify the TAC1R gene, study the effects of cocaine on TACR1 and to analyze the interaction between TACR1 and opioids receptors. We have identified a duplicate of TACR1 gene in zebrafish, designated as tacr1a and tacr1b. Phylogenetic analyses revealed an alignment of these receptors in the Tacr1 fish cluster, with a clear distinction from other TACR1s of amphibians, birds and mammals. Our qPCR results showed that tacr1a and tacr1b mRNAs are expressed during embryonic development. Whole-mount in-situ hybridization showed tacr1s expression in the central nervous system (CNS) and in peripheral tissues. 1.5 μM cocaine induced an upregulation of tacr1a and tacr1b at 24 and 48 hpf (except for tacr1a at 48 hpf, which was downregulated). Contrary, HEK-293 cells transfected with tacr1a and tacr1b and exposed to cocaine showed a downregulation of tacr1s. The knockdown of ZfDOR2 and ZfMOR, opioid receptors, induced a down- and up-regulation of tacr1a and tacr1b, respectively.
In conclusion, tacr1a and tacr1b in zebrafish are widely expressed throughout the CNS and peripherally, suggesting to these tacr1s a critical role during embryogenesis. tacr1a and tacr1b mRNA expression is altered by cocaine exposure and by the knockdown of opioid receptors. Thus, zebrafish can provide clues for a better understanding of the relationship between tachykinin and opioid receptors, in pain and addiction during embryonic development.