Acclimation to different environmental salinities induces molecular endocrine changes in the GH/IGF-I axis of juvenile gilthead sea bream (Sparus aurata L.).
To assess the role of the GH/IGF-I axis in osmotic acclimation of the gilthead seabream Sparus aurata, juvenile specimens were acclimated to four environmental salinities: hyposmotic (5 ‰), isosmotic (12 ‰) and hyperosmotic (40 and 55 ‰). The full-length cDNAs for both pituitary adenylate cyclase-activating peptide (PACAP) and prepro-somatostatin-I (PSS-I), the precursor for mature somatostatin-I (SS-I), were cloned. Hypothalamic PACAP and PSS-I, hypophyseal growth hormone (GH) and prolactin (PRL), and hepatic insulin-like growth factor-I (IGF-I) mRNA expression levels were analyzed in the four rearing salinities tested. PACAP and IGF-I mRNA values increased significantly in response to both 5 and 55 ‰ salinities, showing a U-shaped curve relationship with the basal level in the 40 ‰ group. Hypothalamic PSS-I expression increased strongly in the 55 ‰ environment. GH mRNA levels did not change in any of the tested environmental salinities. PRL mRNA maximum levels were encountered in the 5 and 12 ‰ environments, but significantly down-regulated in the 40 ‰. Plasma cortisol levels significantly increased in the 40 ‰ environment. These results are discussed in relation to the well-known high adaptability of Sparus aurata to different environmental salinities and the role of the GH/IGF-I axis in this process.
Departamento de Biología Marina y Acuicultura, Instituto de Ciencias Marinas de Andalucía, Consejo Superior Investigaciones Científicas (CSIC), 11510, Puerto Real, Cádiz, Spain, khaled.mohammed@icman.csic.es.
Khaled
K
Mohammed-Geba
J M
JM
Mancera
G
G
Martínez-Rodríguez
D000064:Acclimatization / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D013006:Growth Hormone / Q000378:metabolism*; D006854:Hydrocortisone / Q000097:blood; D007031:Hypothalamus / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000235:genetics; D011388:Prolactin / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054712:Salinity; D021541:Sea Bream / Q000502:physiology*
D017931:DNA Primers; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D013006:Growth Hormone; D006854:Hydrocortisone