Effects of thyroid hormone on CRH gene expression in Paralichthys olivaceus at early development stage

ObjectiveThe present study investigated expression of corticotropin releasing hormone (CRH) gene and in-fluence of thyroid hormone on it, in order to provide reference for artificial breeding of Paralichthys olivaceus. MethodCRH gene expression of P. olivaceus at early development was detected by real-time fluorescence quantitative PCR. Thyroid hormone(T3 and T4) level of P. olivaceus larvae and CRH gene expression after exogenous T3 immersion treatment were measured by ELISA method. The interaction between CRH and thyroid hormone at early development stage of P. olivaceus was studied. ResultDuring 1-8 dph, CRH gene expression went through up-down variation, and reached the peak at 5 dph, which was significantly higher than the value at other day ages(P<0.05, the same below). At 10-42 dph, CHR gene expression was mainly in head, and expression in tail increased with growth of P. olivaceus. T4 content gradually in-creased before metamorphosis, and soared at metamorphosis climax, then decreased at metamorphosis postclimax. Com-pared with other early development stages, T3 maintained at a high level during metamorphosis, but the content was lower than T4. After P. olivaceus at 22 dph treated with 50 nmol/L exogenous T3 for 2 hours, the expression of CRH in head and tail significantly increased;but aftet 8 hours, the expression in head and tail significantly decreased. ConclusionAt early metamorphosis stage, P. olivaceus needs to increase CRH expression and accumulate thyroid hormone. Both of them play important roles at early development stage of P. olivaceus and have compensatory effect between each other.