单配制啮齿动物Pair Bond形成的神经调节机制

单配制啮齿动物社会结构的神经生物学原理可以通过实验室研究Social bonding而获得。在本文中,我们探讨了如何利用单配制的草原田鼠(Microtus ochrogaster)作为研究模型揭示pair bond形成的神经调控机制。我们进而探讨了单配制与多配制田鼠之间神经解剖学的差异以及神经化学物质的调节是怎样影响pair bond的。本篇综述还讨论了与pair bond形成有关的神经化学系统之间的相互影响以及pair bond形成过程中的两性差异。最后,我们预测了这一研究领域的未来研究方向以及研究social bonding的神经调控对人类健康的重要性。     

Corticosterone Enhances Kainic Acid-Induced Calcium Elevation in Cultured Hippocampal Neurons

Abstract: Corticosterone, a steroid secreted during stress, increases hippocampal neuronal vulnerability to excitotoxins, hypoxia-ischemia, and antimetabolites. Energy supplementation and N -methyl-d-aspartate receptor antagonists prevent this corticosterone-enhanced neurotoxicity. Because neuronal calcium regulation is energy dependent and a large calcium influx accompanies N -methyl-d-aspartate receptor activation, we investigated whether corticosterone exacerbates the elevation of hippocampal neuronal calcium induced by the glutamatergic excitotoxin kainic acid. Corticosterone caused a 23-fold increase in the magnitude of the calcium response to kainic acid, a sevenfold increase in the peak magnitude of the calcium response, and a twofold increase in calcium recovery time. This corticosterone effect may be energetic in nature as corticosterone decreases hippocampal neuronal glucose transport. Glucose supplementation reduced the corticosterone effect on the magnitude and peak magnitude of the calcium response to kainic acid. Glucose reduction, by the approximate magnitude by which corticosterone inhibits glucose transport, mimicked the corticosterone effect on the peak magnitude of the calcium response to kainic acid. Thus, corticosterone increases calcium after kainic acid exposure in hippocampal neurons in an energy-dependent manner. Elevated calcium is strongly implicated in stimulating neurotoxic cascades during other energetic insults and may be the mechanism for the corticosterone-induced hippocampal neuronal vulnerability and toxicity.     

Effects of reproductive status on behavioral and endocrine responses to acute stress in a biparental rodent, the California mouse (Peromyscus californicus)

In several mammalian species, lactating females show blunted neural, hormonal, and behavioral responses to stressors. It is not known whether new fathers also show stress hyporesponsiveness in species in which males provide infant care. To test this possibility, we determined the effects of male and female reproductive status on stress responsiveness in the biparental, monogamous California mouse (Peromyscus californicus). Breeding (N = 8 females, 8 males), nonbreeding (N = 10 females, 10 males) and virgin mice (N = 12 females, 9 males) were exposed to a 5-min predator-urine stressor at two time points, corresponding to the early postpartum (5-7 days postpartum) and mid/late postpartum (19-21 days postpartum) phases, and blood samples were collected immediately afterwards. Baseline blood samples were obtained 2 days prior to each stress test. Baseline plasma corticosterone (CORT) concentrations did not differ among male or female groups. CORT responses to the stressor did not differ among female reproductive groups, and all three groups showed distinct behavioral responses to predator urine. Virgin males tended to increase their CORT response from the first to the second stress test, while breeding and nonbreeding males did not. Moreover, virgin and nonbreeding males showed significant behavioral changes in response to predator urine, whereas breeding males did not. These results suggest that adrenocortical responses to a repeated stressor in male California mice may be modulated by cohabitation with a female, whereas behavioral responses to stress may be blunted by parental status.     

Behavioral and cardiophysiological responses of common marmosets (Callithrix jacchus) to social and environmental changes

Under captive conditions common marmosets (Callithrix jacchus) show socially monogamous propensities. Male and female form a social bond as characterized by signs of behavioral arousal during separation of the pairmates, high levels of affiliative interactions between pairmates and agonistic responses towards strange conspecifics. In the present study behavioral and cardiophysiological responses of mated individuals of common marmosets were recorded while the animals were in an unfamiliar environment (1) alone, (2) with the pairmate, or (3) with an opposite-sexed stranger. Pairmates of 6 established pairs were tested in 3 replicates yielding a total of 36 trials per experiment. A trial was divided into three 10-min segments (baseline; unfamiliar environment; reunion). Behavioral responses were videotaped with a remote controlled camera system installed within the cage. Systolic (SBP) and diastolic blood pressure (DBP), and heart rate (HR) as well as locomotor activity (ACT) were recorded telemtrically through peritoneally implanted transmitters. The individuals’ responses measured while in an unfamiliar environment was only reduced by the pairmate, but not by an opposite-sexed stranger. No affiliative behaviors occurred between strange conspecifics, whereas aggressive and sexual behaviors were observed. During reunion with the pairmate individuals recovered physiologically. The present study shows that an individualized pair bond exists between pairmates of common marmosets. Further, it becomes evident that establishing a social bond with the pairmate is important for maintaining physiological homeostasis.     

Maintenance of pair bond during the non-reproductive season in a monogamous pipefish <Emphasis Type=Italic>Corythoichthys haematopterus</Emphasis>

During the non-reproductive season, male and female Corythoichthys haematopterus came to a particular site every early morning and performed a series of displays, called greetings, for a few minutes. After exchanging greetings, they had no further interactions during the daytime. This behavioural pattern was basically the same as that observed during the reproductive season. All greeting pairs bred in the following reproductive season if both members were present. These results indicate that mate fidelity of this pipefish is very high and that daily greetings lasting only a few minutes were enough to maintain pair bond all year around.     

Spawning and biparental egg-care in a temperate filefish,Paramonacanthus japonicus (Monacanthidae)

Synopsis Reproductive habits of a temperate filefish, Paramonacanthus japonicus, were studied on a rocky reef at Tsuyazaki, Fukuoka, Japan, from 1989 through 1990. Males had territories of 30–70m² and defended them from conspecific males and potential egg predators such as another filefish, Stephanolepis cirrhifer. Egg masses were found on the sandy bottom in male territories. Individual discrimination of males and females occurring in three male territories revealed that males and females stayed in stable pairs during one month of observation in 1989. In these stable pairs, males fed only within their territories, but females occasionally foraged outside. The occurrence of egg masses within male territories and biparental egg care showed that fish were reproducing as monogamous pairs. Contrary to this, males tagged in 1990 changed their territories after the disappearance of females, and males and females mated polygamously. Spawning was observed only four times during the study period, between 1633 and 1754h. Prior to spawning, the female prepared a spawning bed on the sandy bottom. The male nuzzled the female and the pair spawned, touching their gonopores on the spawning bed. Spawning was very quick and took only 1–3 seconds. The adhesive eggs were spherical with a diameter of 0.56 mm. They were mixed with sand particles and formed a doughnut-shaped mass of about 4 cm in diameter. One egg mass contained 3300–3800 embryos of similar developmental stage, which hatched 2–3 days later. P. japonicus appears to be monogamous but may also practice polygamy when pair-bonds are unstable.     

Stress during adolescence enhances locomotor sensitization to nicotine in adulthood in female, but not male, rats

A wide body of research has indicated that perinatal exposure to stressors alters the organism, notably by programming behavioral and neuroendocrine responses and sensitivity to drugs of abuse in adulthood. Recent evidence suggests that adolescence also may represent a sensitive period of brain development, and yet there has been little research on the long-lasting effects of stressors during this period. We investigated the effects of pubertal social stress (PS; daily 1-h isolation followed by pairing with a new cage mate on postnatal days 33-48) on locomotor sensitization to injections of nicotine and corticosterone response to restraint stress when the rats were adults (approximately 3 weeks after PS). There were no differences among the groups in locomotor activity to injections of saline. However, PS females had enhanced locomotor sensitization to repeated doses of nicotine compared to control (non-stressed; NS) females, whereas PS males and NS males did not differ. PS enhanced the corticosterone response to restraint in male rats previously sensitized to nicotine and decreased the corticosterone response in nonsensitized male rats. In contrast, PS females and NS females did not differ in plasma corticosterone levels in response to restraint stress, but NS females showed enhanced corticosterone release to restraint after sensitization to nicotine. Thus, during adolescence, social stressors can have long-lasting effects, and the effects appear to differ for males and females.     

Review of factors influencing stress hormones in fish and wildlife

Conservation efforts to better understand how wildlife populations respond to environmental change and anthropogenic disturbance has led to a proliferation of research examining physiological indicators of stress response in wildlife. Glucocorticoid stress hormones (GCs), typically cortisol and corticosterone, are among the most frequently measured indicators of the vertebrate stress response. To review the current state of research on stress physiology of free-ranging animals and its application to conservation, we canvassed more than 1000 articles on GC measures in wildlife published since 1969. For 454 studies published since 1990, we assessed the most commonly analysed correlates and disturbances and conducted a meta-analysis on commonly studied species. We noted a prominent divide in the legacies of fish-related analyses and those of higher order vertebrates and the need and opportunity to transfer knowledge between fields. Fish studies most frequently measured physiological indicators, condition, and the relationship between stress and mortality, whereas other vertebrate studies most frequently measured reproduction, condition, and environmental correlates. Correlates that significantly influenced GC levels across all vertebrate groups and are thus important to control for in study design and analyses include density and dispersal of conspecifics, season, reproductive status, and social status. Consistent trends across commonly studied species included positive GC response to capture and handling, reduced GC response related to acclimation, and a lack of correlation between condition and baseline GC levels. Our synthesis within and across diverse taxonomic orders reveals substantial research coverage but a lack of depth in multivariate analyses and a disparity in how correlates are controlled. This paper provides a comprehensive assessment of correlates and disturbances that influence GC measures and, as such, has useful applications to assist conservation physiologists in study design, analysis, and interpretation.     

Covariation between personalities and individual differences in coping with stress:Converging evidence and hypotheses

In the past decade there has been a profusion of studies highlighting covariation between individual differences in stress physiology and behavioural profiles, here called personalities. Such individual differences in ways of coping with stress are relevant both in biomedicine, since different personalities may experience a different stress and disease vulnerability, and in behavioural ecology, since their adaptive value and evolutionary maintenance are the subject of debate. However, the precise way in whi...     

CRF receptors in the nucleus accumbens modulate partner preference in prairie voles

Recent evidence suggests a role for corticotropin-releasing factor (CRF) in the regulation of pair bonding in prairie voles. We have previously shown that monogamous and non-monogamous vole species have dramatically different distributions of CRF receptor type 1 (CRF(1)) and CRF receptor type 2 (CRF(2)) in the brain and that CRF(1) and CRF(2) receptor densities in the nucleus accumbens (NAcc) are correlated with social organization. Monogamous prairie and pine voles have significantly lower levels of CRF receptor type 1 (CRF(1)), and significantly higher levels of type 2 (CRF(2)) binding, in NAcc than non-monogamous meadow and montane voles. Here, we report that microinjections of CRF directly into the NAcc accelerate partner preference formation in male prairie voles. Control injections of CSF into NAcc, and CRF into caudate-putamen, did not facilitate partner preference. Likewise, CRF injections into NAcc of non-monogamous meadow voles also did not facilitate partner preference. In prairie voles, this CRF facilitation effect was blocked by co-injection of either CRF(1) or CRF(2) receptor antagonists into NAcc. Immunocytochemical staining for CRF and Urocortin-1 (Ucn-1), two endogenous ligands for CRF(1) and CRF(2) receptors in the brain, revealed that CRF, but not Ucn-1, immunoreactive fibers were present in NAcc. This supports the hypothesis that local CRF release into NAcc could activate CRF(1) or CRF(2) receptors in the region. Taken together, our results reveal a novel role for accumbal CRF systems in social behavior.     

鸟类应激反应的诱发和影响因素

应激反应是动物应对环境变化或社会压力的重要机制,表现为下丘脑-垂体-肾上腺轴(HPA轴)被激活并产生糖皮质激素。鸟类的糖皮质激素主要是皮质酮。通过检测鸟类体内的皮质酮水平,可以了解鸟类的应激状态水平,进而了解诱发和影响鸟类应激反应的因素,这有助于理解鸟类如何适应环境、如何权衡生活史各阶段的能量分配等。而通过长期监测动物个体的生存和应激状况,对濒危鸟类的保育工作也具有重要参考价值。本文综述了诱发鸟类应激反应的因素,包括天气、捕食压力、食物可获得性、人为干扰和城市化以及社会压力等。归纳出影响鸟类应激反应程度的主要因素,包括光周期、生境、性别、年龄、社会等级和早期经历等8个方面。提出了应激反应在个性、认知、系统发育等领域的应用,以及慢性应激、羽毛皮质酮检测等值得关注的内容。     

Acute stress hyporesponsive period in nestling Thin-billed prions <Emphasis Type="Italic">Pachyptila belcheri</Emphasis>

When confronted with acute stressors, vertebrates show a highly conserved evolved sequence of physiological, hormonal and behavioural responses, including the activation of the hypothalamic–pituitary–adrenal axis. Many young vertebrates show a stress hyporesponsive period, where they exhibit a reduced glucocorticoid response. Here, we analyzed the stress response of nestling Thin-billed prions Pachyptila belcheri and compared chicks with different previous experience with capture and handling. We found that chicks had a stress response, but baseline and peak levels were below those measured in adults. The stress response of the chicks was rapid and followed by fast recovery, such that the total amount of corticosterone released in response to handling was very much lower in chicks than adults. These results indicate that nestling Thin-billed prions exhibit a stress hyporesponsive period. This was not due to habituation, as CORT measurements at baseline and elevated levels were similar in chicks handled daily and naïve chicks. The comparison with other published studies showed that the stress response of chicks usually peaks earlier and lower than in adults, and researchers should take care to measure stress-induced levels at an appropriate sampling time.     

Telomeres:Linking stress and survival,ecology and evolution

Telomeres are protective structures at the ends of eukaryotic chromosomes. The loss of telomeres through cell division and oxidative stress is related to cellular aging, organismal growth and disease. In this way, telomeres link molecular and cellular mechanisms with organismal processes, and may explain variation in a number of important life-history traits. Here, we discuss how telomere biology relates to the study of physiological ecology and life history evolution. We emphasize current knowledge on how ...     

Oleoyl-estrone increases adrenal corticosteroid synthesis gene expression in overweight male rats

Oleoyl-estrone (OE) induces a marked loss of body fat in rats by maintaining energy expenditure, body protein and blood glucose despite decreasing food intake. OE increases glucocorticoids, but they arrest OE lipid-mobilization. We studied here whether OE induces a direct effect on adrenal glands function as part of this feedback regulation. Dietary overweight male rats were given oral 10 nmol/g OE gavages for ten days. A group (PF) of pair-fed to OE rats, and controls received vehicle-only gavages. OE rats lost slightly more body than PF, but had larger adrenal glands. Tissue corticosterone levels, and gene expressions for glucocorticoid-synthesizing enzymes were increased in OE versus controls and PF; thus, we assumed that adrenal growth affected essentially its cortex since OE also lowered the expression of the medullar catecholamine synthesis enzyme genes. Serum corticosterone was higher in PF than in OE and controls, but liver expression of corticosteroid-disposing steroid 5α-reductase was 3× larger in OE than PF and controls. Circulating glucocorticoids changed little under OE, in spite of higher adrenal gland and liver content, hinting at modulation of glucocorticoid turnover as instrumental in their purported increased activity. In conclusion, we have observed that OE considerable enhanced the expression of the genes controlling the synthesis of glucocorticoids from cholesterol in the rat and increasing the adrenal glands’ corticosterone, size and cellularity, but also the liver disposal of corticosteroids, suggesting that OE increases corticosterone synthesis and degradation (i.e. serum turnover), a process not driven by limited energy availability but directly related to the administration of OE.     

Child maltreatment and the developing HPA axis

The developing HPA axis is under strong social regulation in infancy and early childhood and is vulnerable to perturbation in the absence of sensitive, responsive caregiving. Child maltreatment has complex, long-term influences both on basal cortisol levels and on HPA responsivity to pharmacological and psychological stressors, depending on current psychiatric status, current life adversity, age, and most likely, genetic factors. Among the more consistent findings, maltreated children with internalizing problems have elevated basal cortisol most often detected in early AM concentrations, whereas adults maltreated as children often exhibit low basal cortisol levels and elevated ACTH response to psychological stressors. To disentangle these complicated interactions, future research must take the above qualifiers into account, study the transition to puberty, explore the moderating role of candidate genes, and utilize animal models and pharmacological challenges, when ethical, to localize changes in the HPA axis. Post-institutionalized children may provide a model to separate early adverse care histories from current adversity.     

Men in committed, romantic relationships have lower testosterone

Variation in human male testosterone levels may reflect, and effect, differential behavioral allocation to mating and parenting effort. This proposition leads to the hypothesis that, among North American men, those involved in committed, romantic relationships will have lower testosterone levels than men not involved in such relationships. Our study is the first to examine whether being in such a relationship (rather than being married) is the meaningful predictor of male testosterone levels. To test this hypothesis, 122 male Harvard Business School students filled out a questionnaire and collected one saliva sample (from which testosterone level was measured). Results revealed that men in committed, romantic relationships had 21% lower testosterone levels than men not involved in such relationships. Furthermore, the testosterone levels of married men and unmarried men who were involved in committed, romantic relationships did not differ, suggesting that, at least for this sample, male pair bonding status is the more significant predictor of testosterone levels than is marital status.     

Characterization of pituitary–adrenocortical activity in the Malayan flying fox (Pteropus vampyrus)

Pituitary–adrenocortical and gonadal endocrine activity was investigated in a captive colony of Pteropus vampyrus, a highly social Old World fruit bat. Both cortisol and corticosterone were present in plasma, at a ratio of approximately 5:1, respectively. Glucocorticoid but not testosterone levels significantly increased prior to and concomitant with the evening active period. Restraint stress for 15–60 min resulted in a significant and rapid increase in plasma levels of adrenocorticotropic hormone (ACTH) and glucocorticoids. ACTH levels quickly returned to baseline following restraint whereas glucocorticoid levels remained elevated for at least 30 min after restraint ended. Plasma ACTH levels after stress were similar to levels reported after stress in other mammals. Stress-induced glucocorticoid levels were several-fold greater than those reported for most mammals. Restraint for 15 min significantly inhibited testosterone levels. Restraint stress did not affect hormone levels on the morning following restraint. Brief capture, handling, and release of the animals did not elicit increases in these hormones. The physiological responsiveness of the pituitary and adrenal glands, along with P. vampyrus’s documented seasonality and range of social behaviors, makes these bats an excellent model for exploring the general physiology of the hypothalamic–pituitary–adrenal and hypothalamic–pituitary–gonadal axes, as well as social influences on these axes.