Effect of salinity changes on olfactory memory-related genes and hormones in adult chum salmon Oncorhynchus keta.
Studies of memory formation have recently concentrated on the possible role of N-methyl-d-aspartate receptors (NRs). We examined changes in the expression of three NRs (NR1, NR2B, and NR2C), olfactory receptor (OR), and adrenocorticotropic hormone (ACTH) in chum salmon Oncorhynchus keta using quantitative polymerase chain reaction (QPCR) during salinity change (seawater→50% seawater→freshwater). NRs were significantly detected in the diencephalon and telencephalon and OR was significantly detected in the olfactory epithelium. The expression of NRs, OR, and ACTH increased after the transition to freshwater. We also determined that treatment with MK-801, an antagonist of NRs, decreased NRs in telencephalon cells. In addition, a reduction in salinity was associated with increased levels of dopamine, ACTH, and cortisol (in vivo). Reductions in salinity evidently caused NRs and OR to increase the expression of cortisol and dopamine. We concluded that memory capacity and olfactory imprinting of salmon is related to the salinity of the environment during the migration to spawning sites. Furthermore, salinity affects the memory/imprinting and olfactory abilities, and cortisol and dopamine is also related with olfactory-related memories during migration.
Division of Marine BioScience, Korea Maritime and Ocean University, Busan 606-791, Republic of Korea.
Na Na
NN
Kim
Division of Marine BioScience, Korea Maritime and Ocean University, Busan 606-791, Republic of Korea.
Young Jae
YJ
Choi
Future Aquaculture Research Institute, NFRDI, Jeju 699-804, Republic of Korea.
Sang-Gu
SG
Lim
Future Aquaculture Research Institute, NFRDI, Jeju 699-804, Republic of Korea.
Minhwan
M
Jeong
Department of Marine Molecular Biotechnology, Gangneung-Wonju National University, Gangneung 210-702, Republic of Korea.
Deuk-Hee
DH
Jin
Division of Marine BioScience, Korea Maritime and Ocean University, Busan 606-791, Republic of Korea. Electronic address: choic@kmou.ac.kr.
Cheol Young
CY
Choi
D000324:Adrenocorticotropic Hormone / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D004298:Dopamine / Q000097:blood; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D018034:Olfactory Receptor Neurons / Q000378:metabolism; D017685:Oncorhynchus keta / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D054712:Salinity; D012903:Smell / Q000235:genetics*
D012333:RNA, Messenger; D000324:Adrenocorticotropic Hormone; D004298:Dopamine; D006854:Hydrocortisone
Imprinting; Memory; N-methyl-d-aspartate receptors; Olfactory receptor; Oncorhynchus keta; Salinity change