Developmental stage-specific A-to-I editing pattern in the postnatal pineal gland of pigs(Sus scrofa)

Background: RNA editing is a widespread post-transcriptional modification mechanism in mammalian genomes.Although many editing sites have been identified in domestic pigs(Sus scrofa), little is known about the characteristics and dynamic regulation of RNA editing in the pineal gland(PG), a small neuroendocrine gland that synthesizes and secretes melatonin, which is primarily responsible to modulate sleep patterns.Results: This study analyzed the expression of adenosine-to-inosine(A-to-I) editing regulators and profiled the first dynamic A-to-I RNA editome during postnatal PG development. The results identified ADAR1 as the most abundantly expressed ADAR enzyme, which was down-regulated during postnatal PG development. Furthermore,47,284 high-confidence RNA editing sites were identified, the majority of which(93.6%) were of the canonical A-to-I editing type, followed by C-to-T editing. Analysis of its characteristics showed that the A-to-I editing sites mostly localized in SINE retrotransposons PRE-1/Pre0_SS. Moreover, a strong deficiency and preference for guanine nucleotides at positions of one base upstream or downstream were found, respectively. The overall editing level at the puberty stage was higher than at both infancy and adulthood stages. Additionally, genome-wide RNA editing was found to exhibit a dynamic stage-specific fashion(postnatally). Genes that underwent developmental changes in RNA editing were associated with catabolic processes as well as protein localization and transport functions,implying that RNA editing might be responsible for the molecular machineries of the postnatal developing PG.Remarkably, RNA editing in 3′-UTRs might regulate gene expression by influencing miRNA binding during PG development.Conclusions: This study profiles the first comprehensive developmental RNA editome in the pig PG, which contributes to the understanding of the importance of post-transcriptionally mediated regulation during mammalian postnatal PG development. Moreover, this study widely extends RNA editome resources in mammals.

Expression of Clock genes in the pineal glands of newborn rats with hypoxic-ischemic encephalopathy

Clock genes are involved in circadian rhythm regulation, and surviving newborns with hypoxic-ischemic encephalopathy may present with sleep-wake cycle reversal. This study aimed to determine the expression of the clock genes Clock and Bmall, in the pineal gland of rats with hypoxic-ischemic brain damage. Results showed that levels of Clock mRNA v^re not significantly changed within 48 hours after cerebral hypoxia and ischemia. Expression levels of CLOCK and BMAL1 protein were significantly higher after 48 hours. The levels of Bmall mRNA reached a peak at 36 hours, but were significantly reduced at 48 hours. Experimental findings indicate that Clock and Bmall genes were indeed expressed in the pineal glands of neonatal rats. At the initial stage （within 36 hours） of hypoxic-ischemic brain damage, only slight changes in the expression levels of these two genes were detected, followed by significant changes at 36-48 hours. These changes may be associated with circadian rhythm disorder induced by hypoxic-ischemic brain damage.

Molecular mechanisms of seasonal photoperiod effects of the pineal gland on the hippocampus in rats

Background:Based on the theory of“five Zang-organs corresponding to the seasons”in traditional Chinese medicine(TCM),physiological functions including emotions vary with the seasons.We aimed to investigate the seasonal photoperiod effects of melatonin(MT)released from the pineal gland on the MT receptor(MTR)-Gs/Gi-cyclic adenosine monophosphate(cAMP)-protein kinase A(PKA)-cAMP response element-binding protein(CREB)signaling pathway in the hippocampus.Methods:Rats were divided into three groups:control,operation(surgery with pineal gland removal),and pseudo-operation groups(same surgery as operation group but without removing pineal gland),and fed at specific time across the four seasons.The levels of MTR,adenylate cyclase(AC),cAMP,PKA,and CREB in the hippocampus were analyzed using ELISA.The concentrations of Gs and Gi were analyzed using Western blot.The expression of CREB mRNA was detected by PCR.Results:For intragroup comparisons,compared with spring,the levels of Gs/Gi in the control group were higher in summer,autumn,and winter(P=.009 in summer;P<.001 in autumn and winter);the levels of MTR,cAMP,PKA,and CREB in the control group were significantly higher in autumn and winter than in spring(all P<.001).The levels of MTR,cAMP,PKA,and CREB in each season were significantly lower in the operation group than in the control group(all P<.05).Significant differences were noted in Gs/Gi levels between the operation group and control group in spring,autumn,and winter(all P<.05).Conclusion:Our findings suggest that MTR-Gs/Gi-cAMP-PKA-CREB signaling pathway is involved in the seasonal photoperiod effects of the pineal gland on the hippocampus and may underpin seasonal changes in emotions.It can support the prevention and treatment of the seasonal onset of mental disorders,and enrich the theory of“five Zang-organs corresponding to the seasons”.

Melatonin changes in the pineal gland of sleep-deprived rats following habenular nucleus lesion

The habenular nucleus （Hb） is an important structure that regulates the function of the pineal gland which may affect melatonin content in the pineal gland after sleep deprivation （SD）. In the present study, high performance liquid chromatography showed that the melatonin content in the pineal gland was significantly reduced, and y-aminobutyric acid content in the Hb was significantly increased after SD. Furthermore, the melatonin content in the pineal gland was markedly reduced after Hb lesion under normal sleep and SD conditions. Immunohistochemistry showed that the number of Fos-positive neurons was significantly decreased in the lateral and medial Hb after SD. The findings demonstrate that the reduction of melatonin in the pineal gland after SD is related to decreased activity of Hb neurons, and that the Hb can regulate sleep-wake rhythm by influencing melatonin secretion in the pineal gland.

Aluminum and Glyphosate Can Synergistically Induce Pineal Gland Pathology: Connection to Gut Dysbiosis and Neurological Disease

Many neurological diseases, including autism, depression, dementia, anxiety disorder and Parkinson’s disease, are associated with abnormal sleep patterns, which are directly linked to pineal gland dysfunction. The pineal gland is highly susceptible to environmental toxicants. Two pervasive substances in modern industrialized nations are aluminum and glyphosate, the active ingredient in the herbicide, Roundup?. In this paper, we show how these two toxicants work synergistically to induce neurological damage. Glyphosate disrupts gut bacteria, leading to an overgrowth of Clostridium difficile. Its toxic product, p-cresol, is linked to autism in both human and mouse models. p-Cresol enhances uptake of aluminum via transferrin. Anemia, a result of both aluminum disruption of heme and impaired heme synthesis by glyphosate, leads to hypoxia, which induces increased pineal gland transferrin synthesis. Premature birth is associated with hypoxic stress and with substantial increased risk to the subsequent development of autism, linking hypoxia to autism. Glyphosate chelates aluminum, allowing ingested aluminum to bypass the gut barrier. This leads to anemia-induced hypoxia, promoting neurotoxicity and damaging the pineal gland. Both glyphosate and aluminum disrupt cytochrome P450 enzymes, which are involved in melatonin metabolism. Furthermore, melatonin is derived from tryptophan, whose synthesis in plants and microbes is blocked by glyphosate. We also demonstrate a plausible role for vitamin D3 dysbiosis in impaired gut function and impaired serotonin synthesis. This paper proposes that impaired sulfate supply to the brain mediates the damage induced by the synergistic action of aluminum and glyphosate on the pineal gland and related midbrain nuclei.

The Role of Pineal Gland in Regulating Circadian Corticosterone Rhythm and Its Mechanism

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Determination of Melatonin in Rat Pineal Gland and Drug with Flow-Injection Chemiluminescence

A flow-injection chemiluminescence （CL） method for the determination of melatonin based on the CL reaction of melatonin with hydrogen peroxide and sodium hypochlorite （NaOCl） in a basic alkaline solution was developed. The possible CL mechanism has been discussed, and a proposal for the reaction pathway was given that singlet oxygen was clarified to be produced in this reaction system and was responsible for the CL emission. Under the optimized conditions, the linear concentration range of application was 1.0×10^-7-2.5 × 10^-4 moloL-I with a de- tection limit of 5.0 ×10^-8 moloL-1 （S/N= 3）. The relative standard deviation for eight repeated measurements of 1.0×10^-6 mol·L^-1 melatonin was 2.8%. The interferences of several important biological substances, some indole compound, cations and anions were studied. No interference was found for the anions, glucose, starch, most of cations and low concentration （less than 3.0 × 10^-6 mol·L^-1） of some biological substances and indole compound. The method was applied to the determination of melatonin in rat pineal gland and drug with satisfactory results. The sample throughput was 90 injections per hour.

异虎耳草素通过调控Nrf2-NF-κB通路轴减轻松果体损伤大鼠氧化应激和炎症反应

目的探讨异虎耳草素对PCPA诱导的大鼠松果体损伤的保护作用及其机制。方法将40只雄性SD大鼠随机分为正常组,模型组,褪黑素10 mg/kg组和异虎耳草素1.5 mg/kg组,每组10只。除正常组外,其余3组均通过腹腔注射PCPA(450 mg/kg)构建松果体损伤大鼠模型,造模成功后灌胃给药,连续7 d。在给药第6天,采用戊巴比妥钠协同睡眠实验评估各组大鼠的入睡潜伏期和睡眠持续时间。给药结束后,检测血清褪黑素、松果体组织超氧化物歧酶(SOD)、丙二醛(MDA)、谷胱甘肽(GSH)、谷胱甘肽过氧化物酶(GPx)、过氧化氢酶(CAT)、一氧化氮(NO)、白介素(IL)-6、IL-2和肿瘤坏死因子(TNF-α)含量;HE染色观察松果体组织病理学变化;Western blot法检测松果体组织中血红素加氧酶1(HO-1)、醌氧化还原酶1(NQO-1)、核因子E2相关因子2(Nrf2)、Kelch样ECH相关蛋白1(Keap1)、核转录因子-κB(NF-κB)p65、IκB激酶β(IKKβ)、磷酸化IκB激酶β(p-IKKβ)蛋白表达。结果与正常组比较,模型组大鼠松果体细胞结构损伤严重、数目减少,大鼠入睡潜伏期延长,睡眠持续时间缩短,褪黑素、SOD、GSH、GPx和CAT含量降低,NO、MDA、IL-2、TNF-α和IL-6含量升高(P<0.05),Nrf2、NQO1、HO-1、NF-κB p65、IKKβ、p-IKKβ和核NF-κB p65蛋白表达上调,Keap1和胞质NF-κB p65表达下调(P<0.05);与模型组比较,异虎耳草素组大鼠松果体组织损伤得到缓解,入睡潜伏期和睡眠持续时间明显改善,褪黑素、SOD、GSH、GPx和CAT含量增加,NO、MDA、IL-2、TNF-α和IL-6含量减少(P<0.05),Nrf2、NQO1、HO-1、NF-κB p65、IKKβ、p-IKKβ和核NF-κB p65蛋白表达下调,Keap1和胞质NF-κB p65表达上调(P<0.05)。结论异虎耳草素能够通过激活Nrf2信号通路和抑制NF-κB信号通路,抑制氧化应激和炎症反应,减轻大鼠松果体组织损伤,促进褪黑素分泌。

Seasonal variation of melatonin secretion across various segments of the gastrointestinal tract in rats

Objective:To investigate whether melatonin(MT)secretion in different parts of the gastrointestinal tract(GIT)exhibits seasonal variations and its correlation with immune regulation.Methods: Sixty Sprague-Dawley rats were divided into control and model groups,and the pineal gland was removed in the model group.Stomach,jejunum,ileum,and colon tissues were obtained during the spring equinox,summer solstice,beginning of autumn,autumn equinox,and winter solstice.The levels of MT,MT receptors(MR),arylalkylamine N-acetyltransferase(AANAT),hydroxyindole-O-methyltransferase(HIOMT),interleukin-2(IL-2),and interleukin-10(IL-10)in the GIT were measured using enzyme-linked immunosorbent assay.Results: Except for the stomach,the jejunum,ileum,and the colon showed seasonal tendencies in MT secretion.In the control group,MT secretion in the jejunum and ileum was the highest in the long summer,and colonic MT secretion was the highest in winter.In the model group,MT levels in the colon were highest in the summer.The seasonal rhythms of the MR,AANAT,HIOMT,IL-2,and IL-10 in the colon were roughly similar to those of MT,and changed accordingly after pinealectomy.Conclusions: Gastrointestinal MT secretion is related to seasonal changes,and MT secretion in each intestinal segment is influenced by different seasons.The biological effects of MT in the gut are inextricably linked to the mediation of MR,and a hormone-receptor linkage exists between MT and MR.The effect of seasonal changes on the gastrointestinal immune system may be mediated through the regulation of seasonal secretion of MT.

基于“脾应长夏”的胃肠激素季节变化与松果腺褪黑素的相关性研究

目的:观察大鼠血清褪黑素(MT)、胃泌素(GAS)及胃动素(MTL)五季中的含量变化,探讨胃肠动力的季节变化与松果腺褪黑素的相关性,揭示“脾应长夏”内涵。方法:在春、夏、长夏、秋及冬季分批饲养SD雄性大鼠,每一季节中的大鼠随机分为对照组(不做任何处理)和模型组(行松果腺摘除术)。饲养至节气点时间春分、夏至、立秋前1 d、秋分及冬至取材,酶联免疫吸附测定法(ELISA法)检测血清中MT、GAS和MTL含量。结果:春、夏、长夏、秋、冬五季中对照组血清MT、GAS及MTL分泌存在季节性变化节律,均在长夏季节含量最低。松果腺摘除后,模型组中五季血清MT、GAS及MTL分泌的季节性变化节律发生改变,但各指标含量仍在长夏季节最低。长夏季节GAS及MTL分泌与褪黑素具有一致性。结论:胃肠消化系统的功能与中医脾藏象理论密切相关,松果腺褪黑素调节下的胃肠动力的季节变化为中医“脾应长夏”理论生理机制的研究提供了依据。

66例松果体区不同类型肿瘤的CT和MRI表现特征分析

目的探讨松果体区不同类型肿瘤的CT和MRI表现特征。方法对经手术病理证实的66例松果体区肿瘤的CT和MRI资料进行回顾性,纪录肿瘤的类型、大小、形态、钙化、密度、信号、表观弥散系数(ADC)值和强化特征。结果66例中,生殖细胞肿瘤37例,星形细胞瘤13例,松果体细胞肿瘤12例,非典型性畸胎瘤样/横纹肌样瘤2例,室管膜瘤2例。全部肿瘤呈类圆形,最大径范围为1.41-5.15cm,均值为3.25±1.04cm。肿瘤ADC值范围0.52-1.46×10^(-3)mm^(2)/s,均值为1.01±0.25×10^(-3)mm^(2)/s。54.5%瘤内或边缘见钙化;33.3%肿瘤呈混杂密度及信号,增强后肿瘤实性成分均见强化。结论松果体区不同类型的肿瘤CT密度、钙化和MR信号特征及ADC值存在一定差异,结合CT和MRI特征有利于术前正确诊断。

Oxidative stress and lipid peroxidation products:effect of pinealectomy or exogenous melatonin injections on biomarkers of tissue damage during acute pancreatitis

BACKGROUND:Melatonin (N-acetyl-5-methoxytripta-mine) is a free radical scavenger and a strong antioxidant,secreted by the pineal gland.In this study,we evaluated the effects of decreasing and increasing serum melatonin levels on malonyldialdehyde (MDA),superoxide dismutase (SOD),and reduced glutathione (GSH) levels in pancreatic tissue from rats with experimental acute pancreatitis.METHODS:Experimental acute pancreatitis was induced in three groups of Wistar albino rats (10 animals per group) by pancreatic ductal ligation.The first group had only acute pancreatitis and served as the control.Surgical pinealectomy was added to acute pancreatitis in the second group,removing the source of endogenous melatonin (low melatonin levels group).The third group was given 0.1 ml daily intraperitoneal injections of 20 mg/ml melatonin solution for one week (high melatonin levels group).The effects of melatonin levels were evaluated by comparison of the levels of MDA,SOD,and GS in pancreatic tissue.RESULT:We found that intraperitoneal melatonin injections decreased the levels of MDA and increased the levels of SOD and GSH in pancreatic tissue.CONCLUSION:Exogenous melatonin has a preventive effect on lipid peroxidation and oxidative damage in acute pancreatitis.

儿童松果体区不同级别星形细胞瘤的CT和MRI表现特征分析

目的探讨儿童松果体区不同级别星形细胞瘤的CT和MRI表现特征。方法对2005年1月-2022年3月间,经手术病理证实的17例儿童松果体区星形细胞瘤的CT和MRI资料进行回顾性分析,研究肿瘤大小、形态、钙化、密度、信号、表观弥散系数(ADC)值和强化特征。结果17例患者中,WHOⅠ级6例,Ⅱ级7例,Ⅲ及4例;肿瘤呈圆形或类圆形,最大径范围1.95-4.52cm,肿瘤有钙化者4例,Ⅰ-Ⅱ级肿瘤呈稍低密度、Ⅲ级者呈略高密度。肿瘤T1WI呈稍低信号,T_(2)WI呈略高信号,增强后肿瘤实性成分强化明显。肿瘤ADC值范围0.83-1.46×10^(-3)mm^(2)/s。结论儿童松果体区星形细胞瘤CT平扫呈低密度、T1WI低信号,T_(2)WI随级别升高信号由高逐渐减低,ADC值偏高增强后明显强化是其表现特征。

Monochromatic green light stimulation during incubation shortened the hatching time via pineal function in White Leghorn eggs

Background:Effect of monochromatic green light illumination on embryo development has been reported in chickens.The avian pineal gland is an important photo-endocrine organ formed by a mediodorsal protrusion during embryonic development.However,the involvement of pineal gland in the light transduction process remains to be elucidated.In the present study,we investigated the influence of monochromatic green light on hatching time and explored the possible mechanism via pineal function.Results:A total of 600 eggs of White Leghorn(Shaver strain)were incubated under photoperiods of either 12 h of light and 12 h of darkness using monochromatic green light(12L:12D group)or 24 h of darkness(0L:24D group)for 18 d.Compared to 0L:24D group,the green light stimulation shortened the hatching time without extending the hatch window or impairing hatchability.The liver of embryos incubated in the 12L:12D light condition was heavier than those of the 0L:24D group on d 21 post incubation which may be linked to the observed increase in the serum concentration of insulin-like growth factor 1(IGF-1);primary secretion of the liver.Histological structure analysis of pineal gland demonstrated that the light stimulation increased follicle area,wall thickness and lumen area on d 10 and d 12 post incubation.Rhythmic function analysis demonstrated that three clock related genes(brain and muscle ARNT-like-1,BMAL1;circadian locomotor output cycles kaput,CLOCK;and cryptochrome-1,CRY1)and a melatonin rate-limiting enzyme related gene(arylalkylamine N-acetyltransferase,AANAT)were rhythmically expressed in the pineal gland of the 12L:12D group,but not in the 0L:24D group.Simultaneously,the light stimulation also increased the concentration of melatonin(MT),which was linked to hepatocyte proliferation and IGF-1 secretion in previous studies.Conclusions:The 12L:12D monochromatic green light stimulation during incubation shortened hatching time without impairing hatching performance.Pineal gland’s early histological development and maturation of its rhythmic function were accelerated by the light stimulation.It may be the key organ in the photo-endocrine axis that regulates embryo development,and the potential mechanism could be through enhanced secretion of MT in the 12L:12D group which promotes the secretion of IGF-1.

The role of pineal microRNA-325 in regulating circadian rhythms after neonatal hypoxic-ischemic brain damage

Circadian rhythm disorder is a common,but often neglected,consequence of neonatal hypoxic-ischemic brain damage(HIBD).However,the underlying molecular mechanisms remain largely unknown.We previously showed that,in a rat model of HIBD,up-regulation of microRNA-325(miR-325)in the pineal gland is responsible for the suppression of Aanat,a key enzyme involved in melatonin synthesis and circadian rhythm regulation.To better understand the mechanism by which miR-325 affects circadian rhythms in neonates with HIBD,we compared clinical samples from neonates with HIBD and samples from healthy neonates recruited from the First Affiliated Hospital of Soochow University(Dushuhu Branch)in 2019.We found that circulating miR-325 levels correlated positively with the severity of sleep and circadian rhythm disorders in neonates with HIBD.Furthermore,a luciferase reporter gene assay revealed that LIM homeobox 3(LHX3)is a novel downstream target of miR-325.In addition,in miR-325 knock-down mice,the transcription factor LHX3 exhibited an miR-325-dependent circadian pattern of expression in the pineal gland.We established a neonatal mouse model of HIBD by performing doublelayer ligation of the left common carotid artery and exposing the pups to a low-oxygen environment for 2 hours.Lhx3 mRNA expression was significantly down-regulated in these mice and partially rescued in miR-325 knockout mice subjected to the same conditions.Finally,we showed that improvement in circadian rhythm-related behaviors in animals with HIBD was dependent on both miR-325 and LHX3.Taken together,our findings suggest that the miR-325-LHX3 axis is responsible for regulating circadian rhythms and provide novel insights into the identification of potential therapeutic targets for circadian rhythm disorders in patients with neonatal HIBD.The clinical trial was approved by Institutional Review Board of Children’s Hospital of Soochow University(approval No.2015028)on July 20,2015.Animal experiments were approved by Animal Care and Use Committee,School of Medicine,Soochow University,China(approval No.XD-2016-1)on January 15,2016.

基于“心脑一体观”探讨针灸调节褪黑素的作用机理

现代医学认为,脑主导机体的一切生命过程和精神活动,且与周围环境的平衡和调节存在关系。而中医认为“心者,君主之官,神明出焉”,心有主宰身体和神志的功能。褪黑素(MT)是脑室内松果体分泌的一种激素,其在人体的效应有类似中医理论中的“心”“神”作用。如何理解并且融通中医和现代医学两个不同的理论体系,是目前在临床和科研中的重要问题。“心脑一体观”是结合不同理论体系的对同一个生理现象的探讨。本研究基于“心脑一体观”探讨MT失调所致疾病的相关研究,阐释针灸通过调理“心”“神”相关的穴位组合,不仅可改善失眠、抑郁、肥胖、血管性痴呆、胃溃疡等疾病症状,同时具有调节MT水平的作用,为临床针灸治疗MT相关疾病的腧穴配伍提供理论依据。

基于心肌组织ANP、BNP、NT-proBNP水平探讨松果腺对大鼠“心应夏”季节节律变化的调控作用

[目的]通过观察夏至、冬至大鼠心肌组织心钠肽(atrial natriuretic peptide,ANP)、脑钠肽(brain natriuretic peptide,BNP)、氨基末端脑钠肽前体(N-terminal pro-B-type natriuretic peptide,NT-proBNP)分泌量的不同,探讨“心应夏”理论的生物学基础。[方法]雄性SD大鼠随机分为正常对照组、慢性心力衰竭组、松果腺摘除组、复合模型(慢性心衰+松果腺摘除)组,分别于冬至、夏至两个时间点,采用酶联免疫吸附测定(enzyme-linked immunosorbent assay,ELISA)法检测各组大鼠心肌组织中ANP、BNP、NT-proBNP含量。[结果]正常生理情况下,大鼠心肌组织ANP、BNP、NT-proBNP的分泌量均呈现夏低冬高的季节节律变化;松果腺摘除后,大鼠心肌组织ANP、BNP、NT-proBNP的季节节律差异消失,甚至出现倒置。在慢性心衰条件下,大鼠心肌组织ANP、BNP、NT-proBNP的分泌量呈现夏高冬低的节律变化,摘除松果腺后,原有节律消失。[结论]心肌组织ANP、BNP、NT-proBNP是“心应夏”的重要生物学物质基础,它们的分泌存在夏冬季节的节律变化,慢性心衰的病理状态下则呈现与正常生理状态相反的季节节律,松果腺也参与了“心应夏”的季节调节。

Spontaneous pineal apoplexy in a pineal parenchymal tumor of intermediate differentiation

Pineal apoplexy is a rare clinical presentation of pineal parenchymal tumors. We report the curative treatment of a case of pineal parenchymal tumor of intermediate differentiation with spontaneous apoplectic hemorrhage. This case is shown through computed tomography and magnetic resonance imaging of the brain, and is confirmed via histopathological studies. Recurrent upward gaze paresis was observed after the stereotactic biopsy. The paresis required an expeditious tumor resection. The mechanism of the pineal apoplectic hemorrhage remains unclear although it has been observed in different pineal region lesions. Clinical and radiological evidence of the cure 5 years post-surgery is available.

Seasonal photoperiodic influence of pineal melatonin on hypothalamic-pituitary-adrenal axis-hippocampal-receptor in male rats

Background: Based on the effect of seasonal changes on human visceral function, this study investigated the impact of seasonal photoperiod of the pineal body on hypothalamic-pituitary-adrenal axis-hippocampal-receptor in rats, aiming to reveal the mechanism by which pineal gland melatonin regulates the seasonal secretion of hippocampal neurotransmitters.Methods: Vernal equinox, summer solstice, autumn equinox, and winter solstice were selected as four experimental time points, and rats were randomly divided into normal control group, sham operation group, and pinealectomized group. The seasonal changes in corticotropin-releasing hormone(CRH),adrenocorticotropic hormone(ACTH), corticosterone, hypothalamic melatonin receptor(MTR), and hippocampal corticosterone receptor(CORTR) were examined by enzyme-linked immunosorbent assay.Results: Comparing the same group between different seasons, we showed that in the normal control group, CRH, ACTH, corticosterone, and MTR were higher, while CORTR was lower in autumn and winter than in spring(all P <.05). Compared with the normal control group, the pinealectomized group showed higher levels of corticosterone(P =.01), MTR(P =.01), and CORTR(P =.03) during spring;reduced levels of MTR and CORTR(both P <.001) during summer;higher levels of ACTH(P =.001) and MTR(P <.001),and lower levels of CRH(P =.001), corticosterone(P <.001), and CORTR(P =.003) during autumn;and lower levels of CRH(P <.001) and MTR(P =.004), and higher level of ACTH(P <.001) in winter.Conclusions: Seasonal photoperiod acts on the pineal gland to secrete different levels of melatonin,resulting in seasonal changes in the hypothalamic-pituitary-adrenal axis-hippocampal-receptor, which may be the pathophysiological basis for the onset of seasonal affective disorder.