捕食风险对小型哺乳动物行为、神经和内分泌的影响

长期进化过程中,猎物形成了对捕食者先天的敏感性。捕食风险对小型哺乳动物的影响主要包括行为的改变、神经环路的激活和内分泌的变化。行为的改变包括抑制运动活动、降低非防御行为以及改变生活环境。一些研究用c-fos免疫组化的方法测定了大鼠在暴露于猫的气味后大脑被激活的区域,主要包括中间杏仁核、下丘脑腹内侧区、背内侧区、前乳头状核和导水管周围灰质（periaqueductal gray）。猎物对捕食应激的反应还表现在一些内分泌指标的改变,一些激素如皮质酮（Corticoserone,CORT）和促肾上腺皮质激素（Adrenocorticotropic hormone,ACTH）的含量会显著的增加,同时在一些雄性动物中,睾丸激素的含量会有所降低。捕食者和猎物的关系近年来已经成为很多学科研究的有用工具。     

哺乳动物冷应激的主要神经内分泌反应

为便于了解哺乳动物冷应激生理变化的调节机理,介绍了冷应激的主要神经内分泌反应。控制冷应激反应的主要中枢位于下丘脑。冷应激激活交感神经系统,激活下丘脑－垂体－甲状腺轴和下丘脑－垂体－肾上腺轴激素的合成和分泌,引起肾上腺髓质儿茶酚胺分泌增加;同时抑制促生长激素轴、促性腺轴、催乳激素轴的激素分泌。神经肽Y、瘦素、褪黑激素等多种神经肽和激素参与冷应激反应。     

社会行为发育的行为神经内分泌效应

发育过程中行为神经内分泌环境能够调节解剖和生理的长期变化,产生深远的行为效应,所以神经内分泌环境在幼体发育及其行为生理特征的形成中起重要作用。本文综述了神经垂体激素、类固醇激素及它们的受体在社会行为发育中的行为神经内分泌效应;指出该领域有待解决的问题和进一步研究的方向;希望能使人们重视人类发育过程中双亲行为和激素作用对儿童社会行为及其相关神经内分泌特征的影响。     

早期社会隔离对雌性ICR小鼠焦虑水平、社会行为及神经内分泌的影响

许多证据表明早期生活应激会影响动物成年后的行为和神经化学改变,然而该过程的机制还不完全清楚。脑源性神经营养因子(BDNF)、催产素(OT)和糖皮质激素受体(GR)参与对应激的神经适应性反应。本实验将出生3 d后的雌性ICR小鼠幼仔每日隔离3 h直至出生21 d,在60日龄时检测其焦虑水平、社会行为及血清中皮质酮(CORT)和OT的水平,同时检测了中枢BDNF、OT和GR的阳性神经元表达。结果表明,与对照组相比,早期隔离组小鼠的焦虑水平增加,运动性和社会行为减少,同时血清中CORT水平上升、海马CA1和CA2/3区的BDNF及GR的阳性神经元表达下降,下丘脑室旁核和视上核的OT阳性神经元表达减少。这些结果表明,早期社会隔离下调了BDNF、OT和GR的水平,并通过调制应激系统影响雌性ICR小鼠的情绪与社会行为。     

大熊猫母兽育幼早期应激水平与母幼行为的关系

大熊猫(Ailuropoda melanoleuca)属于晚熟性动物,育幼早期是幼仔存活和生长发育的关键时期,也是幼仔最易夭折时期。为了解大熊猫产后应激水平及其与母幼行为之间的关系,从行为适应机制的角度提高幼仔存活率,本研究利用酶联免疫吸附法监测7只处于育幼早期(产后0～75日)母兽粪便皮质醇含量,采用焦点动物取样法观测3对母幼个体的行为。结果显示：(1)育幼早期母兽皮质醇含量随幼仔日龄增长总体呈下降趋势(r=-0.950,P<0.001);(2)幼仔断奶前与断奶后相比,母兽皮质醇含量无显著差异(t=-0.935,P=0.361);(3)母兽皮质醇含量与母幼联系(r=0.918,P<0.001)、幼仔尖叫(r=0.777,P=0.001)和休息行为(r=0.731,P=0.002)均呈极显著正相关,与采食行为呈显著负相关(r=-0.608,P=0.016),而与舔幼仔行为不相关(r=0.366,P=0.179)。结果表明,大熊猫母兽育幼早期粪便皮质醇含量变化与幼仔生长发育有关,推测母兽的应激强度可能随幼仔御寒能力及自主活动能力的提升而降低;皮质醇可能参与母性行为调节,有助于...     

哺乳类早期亲本缺失对子代行为及神经内分泌的影响

亲本投资作为一种早期社会环境对个体发育产生显著的影响。而某些原因会导致哺乳类亲本缺失,造成亲本投资改变。最近有关亲本缺失对子代的影响有较多的研究,本文主要综述了早期母本剥夺、父本剥夺和早期隔离分别对子代成年后情绪、认知及攻击行为、育幼行为和配偶关系的建立等多种社会行为的影响,并总结了这些早期发育的社会环境对神经内分泌的效应,并指出本领域需要解决的问题,希望有助于正确认识哺乳类不同亲本投资对后代行为的影响及相关神经内分泌机制。以上研究可为哺乳类异常行为的发生机制的理解提供重要线索,也为野生动物和实验动物的科学管理提供重要启示。     

慢性应激抑郁状态对大鼠外周神经内分泌因子生物节律的影响

目的：探讨慢性不可预见性应激状态下大鼠外周神经内分泌因子昼夜节律的表达特点。方法：成年雄性SD大鼠60只,随机分为模型组和对照组（n=30）,采用束缚、摇晃、鼠笼倾斜、湿垫料、冷刺激、拥挤（整夜）、断食或断水、夹尾、昼/夜颠倒等慢性不可预知性温和刺激结合孤养方式,每天暴露于2种应激原中饲养21 d,建立抑郁症模型。测定应激前后大鼠糖水偏爱、旷场行为及高架十字迷宫行为学变化。连续24 h分6个时间点（ZT1、ZT5、ZT9、ZT13、ZT17、ZT21）处死动物取血,每个时间点处死5只大鼠。放免法测定6个时间点血清促肾上腺皮质激素（ACTH）含量,ELISA法测定6个相同时间点血浆皮质酮（CORT）、褪黑素（MT）、血管活性肠肽（VIP）含量,采用单一余弦法比较2组大鼠上述各指标的节律周期、振幅、峰值相位、中值的变化特点。结果：与对照组相比,模型大鼠体重增加值明显降低（P<0.01）,各项行为学评分均显著减少（P<0.01）。慢性应激至抑郁样行为充分表达后,血浆ACTH、CORT的相位完全相反,时相大幅度提前,含量波动幅度减小,昼夜分泌节律紊乱;MT的24 h分泌节律完全丧失且整体水平下降,表达量显著降低;VIP虽仍存在24 h节律,但振幅明显降低,峰相位也延迟6 h,且表达量显著提高。结论：慢性应激抑郁状态可导致大鼠外周神经内分泌激素的近日节律非同步于SCN,表现为昼夜节律性和激素分泌量的异常。     

应激对水生动物生长、行为和生理活动的影响

简要介绍了应激对水生动物生长,行为和生理活动影响的研究进展,阐明了应激对动物的生长,行为,体液免疫,细胞免疫以及内分泌功能都有明显地抑制作用,提供水生动物对多种应激源反应的信息,有助于全面了解这方面的研究动态。     

应激诱导对体外培养早期胚胎细胞凋亡的影响

细胞凋亡是早期胚胎清除由于自身或外界环境影响产生的不良细胞的主要途径之一。体外培养的早期胚胎易受一些环境及外源刺激,如氧化剂、机械刺激、重金属和生物类的毒素等产生一系列的刺激性反应,包括细胞转导路径,基因的表达和蛋白的合成,细胞的分裂增殖及凋亡,甚至是坏死;维生素E,维生素C,金属硫蛋白对细胞的凋亡起抑制作用。从凋亡的分子机制进行深入研究,利于从根本上改变胚胎质量,提高囊胚率和附植率。     

模拟捕食者风险对大黄鱼幼鱼行为、游泳能力及应激水平的影响

许多研究表明适当强度的抄网追赶训练能够提高幼鱼感知风险的能力, 塑造出敏捷应对捕食者追赶的行为。大黄鱼生性敏感, 对外界刺激反应较为强烈, 抄网追赶训练能否提高其应对风险的能力尚未知。研究通过对大黄鱼(Larimichthys crocea)幼鱼(80 dpf)进行为期15d和30d, 每天2次, 每次分别0、2.5min、5.0min和7.5min的抄网追赶, 探究了大黄鱼幼鱼在不同水平的抄网追赶下生长、行为、游泳能力和应激水平的变化; 并且在30d刺激结束后的第8天, 再次给予抄网追赶刺激, 以测试停训后大黄鱼幼鱼再次面对刺激时应激水平的变化。结果表明: 不管是短期(15d), 还是较长期(30d)的刺激, 显著性检验表明不同水平的追赶训练对生长的影响不显著, 但效应量和贝叶斯因子表明, 30d的刺激效应更为明显。经过15d刺激后, 显著性检验及效应量都表明追赶刺激对大黄鱼幼鱼对陌生环境的探索能力无显著影响;刺激30d后, 显著性检验以及效应量均表明30 d的追赶刺激大黄鱼幼鱼对陌生环境探索能力的影响要比15d强。此外, 显著性检验、效应量及贝叶斯因子均表明一定水平的刺激能降低大黄鱼幼鱼的皮质醇水平。另外, 显著性检验表明15 d的追赶训练仅对绝对临界游泳速度(U_crita)负面影响显著, 但效应量表明15d和30d的刺激对绝对(U_crita)和相对临界游泳速度(U_critr)负面效应都相当明显。同时, 显著性检验、效应量和贝叶斯因子都表明停训后第8天的大黄鱼幼鱼再次受到刺激时, 其应激水平明显低于未受过训练的个体。总体而言, 抄网刺激训练能有效提高人工养殖大黄鱼幼鱼的野外适应能力。研究结果为深入研究大黄鱼的行为及为大黄鱼放流前的驯化技术研发奠定了一定的基础。     

Effects of domestication on brain structure and behavior in mammals

The domestication of mammals has led to a reduction of brain size in general. There are, however, species-specific differences concerning the degree of mass decrease. Certain parts of the brains are also involved to different degrees but altogether rather unique effects are characteristic for domesticated mammals at different evolutionary levels. These changes in brain size and proportions are compared with behavioral changes due to domestication. They are valued as a result of artificial selection according to human demands, and thus, in zoological terms, they are interpreted as intraspecific adaptations to the special «ecological niche» of domestication.     

Effects of early life social stress on endocrinology,maternal behavior,and lactation in rats

Exposure to early life stress is a predictor of mental health disorders, and two common forms of early life stress are social conflict and impaired maternal care, which are predominant features of postpartum mood disorders. Exposure of lactating female rats to a novel male intruder involves robust social conflict and induces deficits in maternal care towards the F1 offspring. This exposure is an early life social stressor for female F1 pups that induces inefficient lactation associated with central changes in oxytocin (OXT), prolactin (PRL), and arginine vasopressin (AVP) gene expression in adult F1 females.     

Effects of early weaning on reproductive efficiency in beef cows

Six hundred eighty-three mature cows of the Devon, A. Angus, and Hereford breeds were used to investigate the effect of weaning 90 days after calving on the postpartum reproduction (anestrus and pregnancy rate). The calving pariod was 90 days, from September to November (Spring 1976). The breeding period, also of 90 days, began at the end of the calving period and was from December to February (Summer 1977). The calves were separated from their mothers with a mean age of 90 days for the “W” group of cows and 200 days for the “S”.Early weaning increased overall conception in the 90 days breeding period by 43.07% (P < .001) and reduced the postpartum anestrus from 60.42% in the “S” group to 13.79% (difference of 46.63% ? P < .001) in the “W” group.     

Effects of early weaning on the circadian rhythm and behavioral satiety sequence in rats

The objective of this work was to study the effect of early weaning on circadian rhythm and the behavioral satiety sequence in adult rats. Male Wistar rat pups were weaned for separation from the mother at 15 (D15), 21 (D21) and 30 (D30) days old. Body weight and food intake was measured every 30 days until pups were 150 days old. At 90 days of age, the circadian rhythm of food intake was evaluated every 4 h for three days. Behavioral satiety was evaluated at 35 and 100 days of age. This work demonstrated that body weight and food intake were not altered, but the behavioral satiety sequence demonstrated that the D15 group delayed satiety compared with the D30 group at 100 days of age. In the circadian rhythm of the food intake study, early weaning (D15) changed food intake in the intermediary period of the light phase and in the intermediary period of the dark phase. In conclusion, our study showed that early weaning may alter the feeding behavior mainly in relation to satiety and the circadian rhythm of feeding. It is possible that the presence of other environmental stimuli during early weaning can cause hyperphagia and deregulate the mechanisms of homeostasis and body weight control. This study supports theories that depict insults during early life as determinants of chronic diseases.     

社群学习对植食性鸟类和哺乳动物觅食行为的作用

社群学习是动物的一种可塑性行为表现型式。综述了社群学习对植食性鸟类和哺乳动物觅食行为的作用,并述评了其学习机制。社群同伴对动物个体觅食地点、时间和取食方式均有影响,母体摄食的食物信息可通过胎盘和乳汁显著影响幼体的食物选择。动物通过观察学习、嗅闻学习以及味觉厌恶学习,不仅能更快找到食物资源,提高觅食效率,而且能有效降低中毒与被捕食的风险,从而提高其适合度。     

Effects of early weaning and housing conditions on the development of stereotypies in farmed mink

Female mink pups were weaned at 6, 8 or 10 weeks of age and subjected to two different housing conditions. They were either kept together with a single male sibling in traditional mink cages (30x45x90 cm) or housed socially with all litter-mates in an alternative system consisting of three adjoining traditional cages (90x45x90 cm). All cages were supplied with nest boxes. At 5 months of age, the siblings were removed leaving the females socially isolated in the two different cage systems. Females' stereotypies were quantified by repeated scanning observations under the social housing conditions immediately before removal of the siblings, and again at the age of 7 and 9 months, when the animals had stayed solitary in the two systems for 2 and 4 months. Solitary females showed significantly more stereotypies than females under social housing conditions in both cage systems. Stereotypies were more frequent in the smaller traditional cages. Stereotypies declined from 7 to 9 months of age among solitary animals in traditional cages but not in alternative cages. Early-weaned solitary females in traditional cages showed more stereotypies than later-weaned animals, but only when measured at the age of 7 months. It is suggested that early weaning, individual housing and small cages promote the development of stereotypies in farmed mink. The influence of early weaning on stereotypies seems to decline with age, while effects related to individual housing and small cages appear to be more persistent.     

Lateralized brain and neuroendocrine dysregulation as response to traumatic stress

Stressful life events cause a variety of conditions affecting cerebral and neuroendocrine functions. Repeated stressful events also may determine sensitization leading to an increase in responsiveness to stress stimuli. Recent findings suggest that cognitive and emotional dysregulation related to traumatic stress likely is linked to defective inhibitory functions that may also lead to temporo-limbic seizure-like activity, increased vulnerability to stressors, and dysregulated asymmetry in neural activity patterns that may influence interhemispheric dissociation. Together recent data show that dysregulation in the brain asymmetry and mental functioning may be caused by stress-related activation that can influence also the peripheral endocrine glands through the HPA axis and other pathways connecting the CNS and the target endocrine glands.     

Effects of chronic variate stress on feeding behavior and on monoamine levels in different rat brain structures

Chronic variate stress was seen to decrease the ingestion of sweet food when compared to control rats. Brain monoamines are known to be involved in the control of food intake, serotonin appears to be involved in the mechanisms of satiety, and dopamine in mediating appetite or approach behaviors triggered by incentive stimuli associated with rewards. The effect of chronic variate stress on cerebral levels of monoamines was also studied in rats. Increased levels of DOPAC were observed in the frontal cortex and in the hippocampus and an increased 5-HIAA/5-HT ratio was also observed in this latter structure. In the hypothalamus, levels of HVA and DOPAC were decreased, as well as the DOPAC/DA ratio, while no difference was found in amygdala. During the treatment, there were no differences in the consumption of water and regular food between stressed and control animals. An increase in the adrenal weight was observed at the end of the treatment. The results suggest that emotional changes, such as exposure to stress situations can influence feeding behavior, chronic variate stress causes decreased ingestion of sweet food and decreased dopaminergic neurotransmission in hypothalamus. Increased dopamine metabolite levels in the cortex and hippocampus were also observed and some of these modifications may be related to alterations in feeding behavior.     

Prolonged effect of stress at weaning on the brain serotonin metabolism and sexuality of female rats.

Weanling female rats were stressed (by water and food deprivation for two days) and three months later the following indexes were studied: 5-HT and 5-HIAA levels in five brain regions, blood plasma and cerebrospinal fluid (CSF), sexual activity and nocistatin level of the plasma and CSF. The 5-HIAA content of hypothalamus and brainstem was significantly decreased (in the brainstem with one third) and in the striatum significantly increased. Plasma nocistatin level was significantly increased. Meyerson index and lordosis quotient were similar to control, but the estrus frequency almost doubled in the stressed animals. Much more defense reactions were observed in the stressed females during trials of mating. The results demonstrate that, 1) the perinatal period is not only sensitive to the remote-effects of stress but later could also be stress-sensitive critical periods, and 2) the continuously differentiating (e.g. bone marrow) cells are sensitive to late imprinting by stress, as well as to the brain and the sexual system.     

肠道微生物菌群对脑及行为的影响

肠道微生物菌群组成的变化对正常生理的影响及其在疾病中的作用逐渐成为研究热点。肠道微生物菌群通过脑肠轴影响宿主生理学的各个方面,包括脑-肠交流、脑功能甚至行为。对无菌动物、被致病细菌感染的、使用益生菌或用抗生素药物的动物研究表明,肠道微生物菌群可以调节宿主焦虑样症状及行为。研究表明对肠道微生物菌群的调节可能是治疗复杂中枢神经系统失调症的新策略。