Thermal imprinting modifies adult stress and innate immune responsiveness in the teleost sea bream

Abstract

The impact of thermal imprinting on the plasticity of the hypothalamic-pituitary-interrenal (HPI) axis and stress response in an adult ectotherm, the gilthead sea bream (, L.), during its development was assessed. Fish were reared under 4 thermal regimes, and the resulting adults exposed to acute confinement stress and plasma cortisol levels and genes of the HPI axis were monitored. Changes in immune function, a common result of stress, were also evaluated using histomorphometric measurements of melanomacrophages centers (MMCs) in the head kidney and by monitoring macrophage-related transcripts. Thermal history significantly modified the HPI responsiveness in adult sea bream when eggs and larvae were reared at a higher than optimal temperature (HT, 22°C), and they had a reduced amplitude in their cortisol response and significantly upregulated pituitary and head kidney transcripts. Additionally, after an acute stress challenge, immune function was modified and the head kidney of adult fish reared during development at high temperatures (HT and LHT, 18-22°C) had a decreased number of MMCs and a significant downregulation of dopachrome tautomerase. Thermal imprinting during development influenced adult sea bream physiology and increased plasma levels of glucose and sodium even in the absence of an acute stress in fish reared under a high-low thermal regime (HLT, 22-18°C). Overall, the results demonstrate that temperature during early development influences the adult HPI axis and immune function in a teleost fish.

Thermal imprinting modifies bone homeostasis in cold challenged sea bream (Sparus aurata, L.)

“…However, significant differences in mass and length existed between fish from the different thermal regimes (P<0.001; Table 1). The biometric differences detected in the present study between thermally imprinted fish were confirmed in a subsequent stress-challenge experiment performed with 9-month post-hatch sea bream from the same stock of fish (Mateus et al, 2017 To assess whether thermal imprinting could modify the physiological response of young-adult sea bream subjected to a cold water challenge, duplicate tanks of fish from each thermal regime (LT, LHT, HT and HLT) were randomly divided into two groups: the water temperature of the control groups was 23.0±1.0°C and the cold-challenge groups was 13.0±1.0°C (Fig. 1B).…”

“…A notable feature in the thermally imprinted fish was that, in two independent experiments with 7-month-old ( present study) and 9-month-old (Mateus et al 2017) thermally imprinted sea bream, the results for the plasma chemistry under control conditions (23±1°C) were similar. This suggests that thermal imprinting caused a persistent physiological change that was not affected by age or time of year.…”

“…In fact, in a previous study, exposure to an acute stress challenge of slightly older fish (9 months old) from the same population of fish revealed that thermal imprinting caused significant changes in the central stress axis (Mateus et al, 2017).…”

“…700-900 per thermal regime) were generated and were used for several independent experiments (Garcia de la Serrana et al, 2012;Mateus et al, 2017). Fish used for the present coldchallenge experiment were age matched (7 months post-hatch).…”

Modulation of Pituitary Response by Dietary Lipids and Throughout a Temperature Fluctuation Challenge in Gilthead Sea Bream

“…Reactions were incubated for 10 min at 25 • C and then 60 min at 42 • C, followed by enzyme inactivation for 10 min at 70 • C. cDNA was then stored at −20 • C until use. Primers used to amplify the pituitary hormones (tsh, gh, pomca and pomcb) and pituitary receptors (trα, trβ and gr) have been previously described in [56,57] Transcripts' abundance was measured by quantitative real-time PCR (qPCR) in individual pituitary cDNAs from each experimental group, using the relative standard curve method and EvaGreen chemistry. The copy numbers of target and reference genes was calculated as described in [58] using the equation:…”