Effects of dietary caffeine on growth,body composition,somatic indexes,and cerebral distribution of acetyl‐cholinesterase and nitric oxide synthase in gilthead sea bream (Sparus aurata), reared in winter temperature

This study aims at examining the effect of caffeine administration on growth, feed efficiency, and consumption of sea bream (Sparus aurata), reared in winter temperatures. Moreover, it is questioned whether caffeine has a central action in the brain and its effects are partly mediated via central brain mechanisms. For this, we studied the influences of caffeine treatment on the cerebral pattern of the cholinergic neurotransmission and the novel neuromodulator nitric oxide (NO), by means of acetyl‐cholinesterase (AchE) and nitric oxide synthase (NOS) histochemistry. Five different diets containing 0.0, 0.1, 1.0, 2.0 and 5.0 g caffeine kg^?1 of diet were administrated to five groups of fish. Caffeine adversely affected sea‐bream growth at a concentration higher than 1 g kg^?1 diet and increased feed conversion ratio in the treatments of 2 and 5 g kg^?1 (P < 0.05). The daily consumption of feeds was similar to all groups, indicating that caffeine did not influence diet palatability. AChE‐ and NADPH‐diaphorase histochemistry showed densely labeled cells and fibers mainly in dorsal telencephalon, preoptic, pretectal, hypothalamic areas, optic tectum, reticular formation, cerebellum and motor nuclei. When compared with matched caffeine‐treated animals, no differences in the histochemical pattern and cell densities of cerebral AChE and NADPH‐diaphorase were found.