Distribution of galanin receptor 2b neurons and interaction with galanin in the zebrafish central nervous system.
Galanin is a multifunctional neuropeptide that is implicated in the modulation of physiological processes, including nociception, cognition, feeding behavior, neuronal growth, and reproduction. The physiological effects of galanin are mediated through its interaction with three different G protein-coupled receptors, i.e., GALR1, GALR2, and GALR3. Unlike mammals, zebrafish have four different receptors for galanin, diversified from GALR1 (GAL1a and GALR1b) and GALR2 (GALR2a and GALR2b). Despite the importance of galanin in the central nervous system (CNS), no information has been reported regarding GalR2 in zebrafish CNS. In this study, we found that galr2a is expressed at low levels in restricted areas of the brain; however, galr2b was widely expressed in CNS including olfactory bulb, midbrain tegmentum, preoptic region, dorsal thalamus, posterior tuberculum, postoptic commissure, hindbrain, and spinal cord. To further analyze the distribution of GALR2b neurons and their interaction with GAL, we generated Tg(galr2b:egfp) zebrafish, which express enhanced green fluorescent protein (EGFP) under the control of a galr2b promoter. Investigation of the CNS of transgenic reporter zebrafish revealed that galr2b:EGFP(+) neurons are distributed and interact with galanin-immunoreactive (galanin-IR) cells in various regions of the brain and spinal cord. We found that in some regions of the brain and spinal cord, galanin-IR nerve cells were not observed near galr2b:EGFP neurons, suggesting that GALR2b may have the potential to interact with other ligands instead of galanin in these regions.
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
Eunmi
E
Kim
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
Inyoung
I
Jeong
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
Suhyun
S
Kim
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
Hwan-Ki
HK
Kim
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
Dong-Won
DW
Lee
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea.
Boa
B
Kim
Graduate School of Medicine, Korea University, Seoul 136-705, Republic of Korea.
Jae Young
JY
Seong
Comparative Biomedical Research Branch, Research Institute, National Cancer Center, Goyang-si, Gyeonggi-do 410-769, Republic of Korea.
Young-Ki
YK
Bae
Genomic Design Bioengineering Company, Daejeon 306-230, Republic of Korea.
Jae-Ho
JH
Ryu
Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea. Electronic address: hcpark67@korea.ac.kr.
Hae-Chul
HC
Park
D000818:Animals; D001921:Brain / Q000378:metabolism*; D005260:Female; D029941:Fish Proteins / Q000032:analysis; D019004:Galanin / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D044092:Receptor, Galanin, Type 2 / Q000032:analysis* / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism*; D015027:Zebrafish
D029941:Fish Proteins; D044092:Receptor, Galanin, Type 2; D019004:Galanin
Central nervous system; Galanin; Galanin receptor; Neuropeptide; Zebrafish