Félix Francisca, Oliveira Catarina C V, Martín Ignacio, Manchado Manuel, Sánchez-Vázquez Francisco J, Cabrita Elsa, Vera Luisa M
Centre of Marine Sciences, CCMAR/CIMAR-LA), University of Algarve, Gambelas Campus, 8005-139, Faro, Portugal.
Department of Physiology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100, Murcia, Spain.
Fish Physiol Biochem. 2025 May 1;51(3):88. doi: 10.1007/s10695-025-01502-1.
Fish gonadal melatonin production is still unexplored and could contribute to a better understanding of its role in reproduction control, especially for species with reproductive impairments. This study aimed to comprehend if Senegalese sole testes are an extra-pineal production site of melatonin and if it has seasonal and daily variations. Wild and F1 broodstocks were sampled in the breeding season (BS) and out of the reproductive season (OS), at mid-light (ML) and mid-dark (MD) daytimes. Blood plasma melatonin concentration was determined by radioimmunoassay (RIA). The expression of genes involved in melatonin biosynthesis (tph1a, tph2, hiomt1, aanat1a, aanat1b, and aanat2) and melatonin receptors (mel1, mel1c, and mel2) was evaluated in the brain, eye, and testis by quantitative real-time PCR (qPCR). Plasma melatonin concentration in wild sole displayed day/night differences in both seasons (average ML: 36 ± 22 pg/mL, MD: 108 ± 63 pg/mL), whereas differences in the F1 broodstock were only found OS (ML: 100 ± 54 pg/mL, MD: 187 ± 88 pg/mL). Gene expression of mel1 and mel2 receptors, and tph1a, aanat1a, aanat2, and hiomt1 enzymes was detected and quantified in the fish testes. Moreover, daily and seasonal fluctuations in the expression of those genes were found in all tissues and broodstock groups. However, the F1 group showed distinct gene expression patterns compared to the wild type, suggesting a disruption in the circadian system. This study revealed that Senegalese sole testes are a melatonin production site and, at the same time, suggested a dysregulation in the hypothalamus-pituitary-gonad (HPG) axis of F1 males.
鱼类性腺褪黑素的产生仍未得到充分研究，这可能有助于更好地理解其在生殖控制中的作用，特别是对于那些存在生殖障碍的物种。本研究旨在了解塞内加尔鳎鱼的睾丸是否是褪黑素的一个松果体以外的产生部位，以及它是否存在季节性和每日变化。在繁殖季节（BS）和非繁殖季节（OS）的中午光照（ML）和午夜黑暗（MD）时段，对野生和F1亲鱼进行采样。通过放射免疫分析法（RIA）测定血浆褪黑素浓度。通过定量实时PCR（qPCR）评估大脑、眼睛和睾丸中参与褪黑素生物合成的基因（tph1a、tph2、hiomt1、aanat1a、aanat1b和aanat2）以及褪黑素受体（mel1、mel1c和mel2）的表达。野生鳎鱼血浆褪黑素浓度在两个季节均表现出昼夜差异（平均ML：36±22 pg/mL，MD：108±63 pg/mL），而F1亲鱼仅在非繁殖季节存在差异（ML：100±54 pg/mL，MD：187±88 pg/mL）。在鱼类睾丸中检测并定量了mel1和mel2受体以及tph1a、aanat1a、aanat2和hiomt1酶的基因表达。此外，在所有组织和亲鱼组中均发现了这些基因表达的每日和季节性波动。然而，与野生型相比，F1组显示出不同的基因表达模式，表明昼夜节律系统存在紊乱。本研究表明，塞内加尔鳎鱼的睾丸是褪黑素的一个产生部位，同时也提示F1雄性下丘脑-垂体-性腺（HPG）轴存在失调。
