Adamska Iwona, Malz Monika, Lewczuk Bogdan, Blügental Natalia, Markowska Magdalena Aleksandra, Meronka Robert, Majewski Paweł Marek
Department of Animal Physiology, Faculty of Biology, University of Warsaw, Warsaw, Poland.
Department of Histology and Embryology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland.
Front Physiol. 2019 Jan 15;9:1972. doi: 10.3389/fphys.2018.01972. eCollection 2018.
The avian pineal gland is one of three central biological clocks that contain all the components of a circadian system: a photoreceptive input, oscillator, and rhythmically secreted melatonin (MEL) as an effector. The biosynthesis of MEL is regulated by the neurotransmitters noradrenaline (NA), vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase-activating polypeptide (PACAP). The aim of the present study was to characterize the daily profile of neurotransmitters and their receptors in the pineal gland of male Hy-Line chickens housed under controlled light (12:12 light:dark) conditions. The pineal glands were isolated from 16-day-old birds every 2 h over a 24-h period, immediately after decapitation. The catecholamine content was measured using HPLC with electrochemical detection, whereas expression of VIP and PACAP was measured using quantitative real-time PCR (RT-qPCR) assays and Western blotting. Expression of the neurotransmitter receptors was also measured using RT-qPCR. We found daily changes in NA content, with elevated nocturnal levels, whereas the NA receptor was expressed in antiphase. Although we did not observe daily changes in VIP and PACAP protein levels, we found prominent diurnal changes in the expression of the and genes. We also detected precursors of NA, 3,4-dihydroxy-L-phenylalanine (DOPA), and dopamine (DA) in the pineal glands, in addition to the DA metabolites. Our results provide the first evidence that the pineal gland itself may synthetize the neurotransmitters needed to regulate MEL biosynthesis.
禽类松果体是三个中央生物钟之一，包含昼夜节律系统的所有组成部分：光感受输入、振荡器以及作为效应器有节律分泌的褪黑素（MEL）。MEL的生物合成受神经递质去甲肾上腺素（NA）、血管活性肠肽（VIP）和垂体腺苷酸环化酶激活多肽（PACAP）调节。本研究的目的是表征在可控光照（12:12光照:黑暗）条件下饲养的雄性海兰鸡松果体中神经递质及其受体的每日变化情况。在24小时内每隔2小时从16日龄的鸡身上分离松果体，断头后立即进行。使用带电化学检测的高效液相色谱法测量儿茶酚胺含量，而使用定量实时PCR（RT-qPCR）分析和蛋白质印迹法测量VIP和PACAP的表达。还使用RT-qPCR测量神经递质受体的表达。我们发现NA含量有每日变化，夜间水平升高，而NA受体呈反相表达。虽然我们未观察到VIP和PACAP蛋白水平的每日变化，但我们发现 和 基因的表达有明显的昼夜变化。除了多巴胺（DA）代谢产物外，我们还在松果体中检测到NA的前体3,4-二羟基-L-苯丙氨酸（DOPA）和多巴胺（DA）。我们的结果提供了首个证据，表明松果体自身可能合成调节MEL生物合成所需的神经递质。
