1
|
Mutwill AM, Schielzeth H, Richter SH, Kaiser S, Sachser N. Conditional on the social environment? Roots of repeatability in hormone concentrations of male guinea pigs. Horm Behav 2023; 155:105423. [PMID: 37713739 DOI: 10.1016/j.yhbeh.2023.105423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/20/2023] [Accepted: 08/23/2023] [Indexed: 09/17/2023]
Abstract
Individual differences in behavioral and physiological traits among members of the same species are increasingly being recognized as important in animal research. On the group level, shaping of behavioral and hormonal phenotypes by environmental factors has been reported in different taxa. The extent to which the environment impacts behavior and hormones on the individual level, however, is rather unexplored. Hormonal phenotypes of guinea pigs can be shaped by the social environment on the group level: pair-housed and colony-housed males differ systematically in average testosterone and stressor-induced cortisol levels (i.e. cortisol responsiveness). The aim of the present study was to evaluate whether repeatability and individual variance components (i.e. between- and within-individual variation) of hormonal phenotypes also differ in different social environments. To test this, we determined baseline testosterone, baseline cortisol, and cortisol responsiveness after challenge in same-aged pair-housed and colony-housed guinea pig males over a period of four months. We found comparable repeatability for baseline cortisol and cortisol responsiveness in males from both social conditions. In contrast, baseline testosterone was repeatable only in males from colonies. Interestingly, this result was brought about by significantly larger between-individual variation of testosterone, that was not explained by differences in dominance rank. Individualized social niches differentiated under complex colony, but not pair housing, could be an explanation for this finding.
Collapse
Affiliation(s)
- Alexandra M Mutwill
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany.
| | - Holger Schielzeth
- Population Ecology Group, Institute of Ecology, Friedrich Schiller University, Dornburgerstr. 159, 07743 Jena, Germany
| | - S Helene Richter
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany
| |
Collapse
|
2
|
Mutwill AM, Schielzeth H, Zimmermann TD, Richter SH, Kaiser S, Sachser N. Individuality meets plasticity: Endocrine phenotypes across male dominance rank acquisition in guinea pigs living in a complex social environment. Horm Behav 2021; 131:104967. [PMID: 33862349 DOI: 10.1016/j.yhbeh.2021.104967] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 11/28/2022]
Abstract
The time of dominance rank acquisition is a crucial phase in male life history that often affects reproductive success and hence fitness. Hormones such as testosterone and glucocorticoids can influence as well as be affected by this process. At the same time, hormone concentrations can show large individual variation. The extent to which such variation is repeatable, particularly in dynamic social settings, is a question of current interest. The aim of the present study was therefore to investigate how dominance rank and individual differences contribute to variance in hormone concentrations during male rank acquisition in a complex social environment. For this purpose, dominance rank as well as baseline testosterone, baseline cortisol, and cortisol responsiveness after exposure to a novel environment were determined in colony-housed guinea pig males from late adolescence through adulthood. Hormone-dominance relationships and repeatability of hormone measures beyond their relation to rank were assessed. There was a significant positive relationship between baseline testosterone and rank, but this link became weaker with increasing age. Baseline cortisol or cortisol responsiveness, in contrast, were not significantly related to dominance. Notably, all three endocrine parameters were significantly repeatable independent of dominance rank from late adolescence through adulthood. Baseline testosterone and cortisol responsiveness showed a significantly higher repeatability than baseline cortisol. This suggests that testosterone titres and cortisol responsiveness represent stable individual attributes even under complex social conditions.
Collapse
Affiliation(s)
- Alexandra M Mutwill
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany; Münster Graduate School of Evolution, University of Münster, Hüfferstr. 1a, 48149 Münster, Germany.
| | - Holger Schielzeth
- Population Ecology Group, Institute of Ecology, Friedrich Schiller University, Dornburgerstr. 159, 07743 Jena, Germany
| | - Tobias D Zimmermann
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany
| | - S Helene Richter
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany; Münster Graduate School of Evolution, University of Münster, Hüfferstr. 1a, 48149 Münster, Germany
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany; Münster Graduate School of Evolution, University of Münster, Hüfferstr. 1a, 48149 Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, University of Münster, Badestr. 13, 48149 Münster, Germany; Münster Graduate School of Evolution, University of Münster, Hüfferstr. 1a, 48149 Münster, Germany
| |
Collapse
|
3
|
Mutwill AM, Zimmermann TD, Reuland C, Fuchs S, Kunert J, Richter SH, Kaiser S, Sachser N. High Reproductive Success Despite Queuing - Socio-Sexual Development of Males in a Complex Social Environment. Front Psychol 2019; 10:2810. [PMID: 31920852 PMCID: PMC6928119 DOI: 10.3389/fpsyg.2019.02810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 11/28/2019] [Indexed: 11/13/2022] Open
Abstract
The start of actual breeding in male social mammals can occur long after individuals attain sexual maturity. Mainly prevented from reproduction by older and dominant males, young males often queue until strong enough to compete for favorable social positions and, in this way, to obtain access to females. However, to what extent maturing males also apply tactics to reproduce before this time is largely unknown. Therefore, the aim of the present study was to elucidate male socio-sexual development from onset of sexual maturity through first mating success until the achievement of a stable social position in a complex social environment. For this purpose, guinea pigs were used as a model system and reproductive success of males living in large mixed-sex colonies was assessed during their first year of life. As a reference, males in a mixed-sex pair situation were examined. Pair-housed males reproduced for the first time around the onset of sexual maturity whereas colony-housed males did so much later in life and with a considerably higher variance. In colonies, reproductive success was significantly affected by dominance status. Dominance itself was age-dependent, with older males having significantly higher dominance ranks than younger males. Surprisingly, both younger and older colony-housed males attained substantial reproductive success of comparable amounts. Thus, younger males reproduced irrespective of queuing and already before reaching a high social status. This mating success of maturing males was most likely achieved via several reproductive tactics which were flexibly applied with the onset of sexual maturity. The period of socio-sexual development before a stable social position is established may, therefore, be a time during which male mammals use flexible behavioral tactics to achieve reproductive success more frequently than commonly is presumed. In addition, the findings strongly indicate that high behavioral plasticity exists well beyond sexual maturity.
Collapse
Affiliation(s)
- Alexandra M Mutwill
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | | | - Charel Reuland
- Department of Behavioural Biology, University of Münster, Münster, Germany
| | - Sebastian Fuchs
- Faculty of Statistics, Technical University of Dortmund, Dortmund, Germany
| | - Joachim Kunert
- Faculty of Statistics, Technical University of Dortmund, Dortmund, Germany
| | - S Helene Richter
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | - Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Münster Graduate School of Evolution, University of Münster, Münster, Germany
| | - Norbert Sachser
- Department of Behavioural Biology, University of Münster, Münster, Germany.,Münster Graduate School of Evolution, University of Münster, Münster, Germany
| |
Collapse
|
4
|
Yohn CN, Leithead AB, Ford J, Gill A, Becker EA. Paternal Care Impacts Oxytocin Expression in California Mouse Offspring and Basal Testosterone in Female, but Not Male Pups. Front Behav Neurosci 2018; 12:181. [PMID: 30210315 PMCID: PMC6123359 DOI: 10.3389/fnbeh.2018.00181] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/02/2018] [Indexed: 12/20/2022] Open
Abstract
Natural variations in parenting are associated with differences in expression of several hormones and neuropeptides which may mediate lasting effects on offspring development, like regulation of stress reactivity and social behavior. Using the bi-parental California mouse, we have demonstrated that parenting and aggression are programmed, at least in part, by paternal behavior as adult offspring model the degree of parental behavior received in development and are more territorial following high as compared to low levels of care. Development of these behaviors may be driven by transient increases in testosterone following paternal retrievals and increased adult arginine vasopressin (AVP) immunoreactivity within the bed nucleus of the stria terminalis (BNST) among high-care (HC) offspring. It remains unclear, however, whether other neuropeptides, such as oxytocin (OT), which is sensitive to gonadal steroids, are similarly impacted by father-offspring interactions. To test this question, we manipulated paternal care (high and low care) and examined differences in adult offspring OT-immunoreactive (OT-ir) within social brain areas as well as basal T and corticosterone (Cort) levels. HC offspring had more OT-ir within the paraventricular nucleus (PVN) and supraoptic nucleus (SON) than low-care (LC) offspring. Additionally, T levels were higher among HC than LC females, but no differences were found in males. There were no differences in Cort indicating that our brief father-pup separations likely had no consequences on stress reactivity. Together with our previous work, our data suggest that social behavior may be programmed by paternal care through lasting influences on the neuroendocrine system.
Collapse
Affiliation(s)
- Christine N Yohn
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States.,Department of Psychology, Rutgers University, Piscataway, NJ, United States
| | - Amanda B Leithead
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| | - Julian Ford
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| | - Alexander Gill
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| | - Elizabeth A Becker
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| |
Collapse
|
5
|
Emmerson MG, Spencer KA. Group housing during adolescence has long-term effects on the adult stress response in female, but not male, zebra finches (Taeniopygia guttata). Gen Comp Endocrinol 2018; 256:71-79. [PMID: 28694052 PMCID: PMC5771470 DOI: 10.1016/j.ygcen.2017.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 06/02/2017] [Accepted: 07/06/2017] [Indexed: 11/23/2022]
Abstract
Adolescent social interactions can have long-term effects on physiological responses to stressors in later-life. A larger adolescent group size can result in higher stressor-induced secretion of glucocorticoids in adulthood. The effect may be due to a socially-mediated modulation of gonadal hormones, e.g. testosterone. However, group size (number of animals) has been conflated with social density (space per animal). Therefore it is hard to determine the mechanisms through which adolescent group size can affect the stress response. The current study aimed to tease apart the effects of group size and social density during adolescence on the physiological stress response and gonadal hormone levels in adulthood. Adolescent zebra finches were housed in groups varying in size (2 vs. 5 birds per cage) and density (0.03m3 vs. 0.06m3 per bird) during early adolescence (day 40-60). Density was only manipulated in birds raised in groups of five. Glucocorticoid concentration secreted in response to a standard capture and restraint stressor was quantified in adolescence (day 55±1) and adulthood (day 100+). Basal gonadal hormone concentrations (male testosterone, female estradiol) were also quantified in adulthood. Female birds housed in larger groups, independent of social density, secreted a higher glucocorticoid concentration 45min into restraint regardless of age, and had higher peak glucocorticoid concentration in adulthood. Adult gonadal hormone concentrations were not affected by group size or density. Our results suggest that group size, not density, is a social condition that influences the development of the endocrine response to stressors in female zebra finches, and that these effects persist into adulthood. The findings have clear relevance to the social housing conditions necessary for optimal welfare in captive animals, but also elucidate the role of social rearing conditions in the emergence of responses to stressors that may persist across the lifespan and affect fitness of animals in wild populations.
Collapse
Affiliation(s)
- Michael G Emmerson
- University of St Andrews, School of Psychology & Neuroscience, St Mary's Quad, South Street, St Andrews, Fife KY16 9JP, Scotland, United Kingdom.
| | - Karen A Spencer
- University of St Andrews, School of Psychology & Neuroscience, St Mary's Quad, South Street, St Andrews, Fife KY16 9JP, Scotland, United Kingdom.
| |
Collapse
|
6
|
Yohn CN, Leithead AB, Ford J, Gill A, Becker EA. Paternal Care Impacts Oxytocin Expression in California Mouse Offspring and Basal Testosterone in Female, but Not Male Pups. Front Behav Neurosci 2018. [PMID: 30210315 DOI: 10.3389/fnbeh.2018.00181/bibtex] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023] Open
Abstract
Natural variations in parenting are associated with differences in expression of several hormones and neuropeptides which may mediate lasting effects on offspring development, like regulation of stress reactivity and social behavior. Using the bi-parental California mouse, we have demonstrated that parenting and aggression are programmed, at least in part, by paternal behavior as adult offspring model the degree of parental behavior received in development and are more territorial following high as compared to low levels of care. Development of these behaviors may be driven by transient increases in testosterone following paternal retrievals and increased adult arginine vasopressin (AVP) immunoreactivity within the bed nucleus of the stria terminalis (BNST) among high-care (HC) offspring. It remains unclear, however, whether other neuropeptides, such as oxytocin (OT), which is sensitive to gonadal steroids, are similarly impacted by father-offspring interactions. To test this question, we manipulated paternal care (high and low care) and examined differences in adult offspring OT-immunoreactive (OT-ir) within social brain areas as well as basal T and corticosterone (Cort) levels. HC offspring had more OT-ir within the paraventricular nucleus (PVN) and supraoptic nucleus (SON) than low-care (LC) offspring. Additionally, T levels were higher among HC than LC females, but no differences were found in males. There were no differences in Cort indicating that our brief father-pup separations likely had no consequences on stress reactivity. Together with our previous work, our data suggest that social behavior may be programmed by paternal care through lasting influences on the neuroendocrine system.
Collapse
Affiliation(s)
- Christine N Yohn
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
- Department of Psychology, Rutgers University, Piscataway, NJ, United States
| | - Amanda B Leithead
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| | - Julian Ford
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| | - Alexander Gill
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| | - Elizabeth A Becker
- Department of Psychology, Saint Joseph's University, Philadelphia, PA, United States
| |
Collapse
|
7
|
Social experience during adolescence influences how male zebra finches (Taeniopygia guttata) group with conspecifics. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1668-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
8
|
Siegeler K, Wistuba J, Damm OS, von Engelhardt N, Sachser N, Kaiser S. Early social instability affects plasma testosterone during adolescence but does not alter reproductive capacity or measures of stress later in life. Physiol Behav 2013; 120:143-9. [DOI: 10.1016/j.physbeh.2013.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/25/2013] [Accepted: 08/07/2013] [Indexed: 11/17/2022]
|
9
|
Sachser N, Kaiser S, Hennessy MB. Behavioural profiles are shaped by social experience: when, how and why. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120344. [PMID: 23569292 DOI: 10.1098/rstb.2012.0344] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The comprehensive understanding of individual variation in behavioural profiles is a current and timely topic not only in behavioural ecology, but also in biopsychological and biomedical research. This study focuses on the shaping of behavioural profiles by the social environment in mammals. We review evidence that the shaping of behavioural profiles occurs from the prenatal phase through adolescence and beyond. We focus specifically on adolescence, a sensitive phase during which environmental stimuli have distinctive effects on the modulation of behavioural profiles. We discuss causation, in particular, how behavioural profiles are shaped by social stimuli through behavioural and neuroendocrine processes. We postulate a central role for maternal hormones during the prenatal phase, for maternal behaviour during lactation and for the interaction of testosterone and stress hormones during adolescence. We refer to evolutionary history and attempt to place developmental shaping into broader evolutionary historical trends. Finally, we address survival value. We argue that the shaping of behavioural profiles by environmental stimuli from the prenatal phase through adolescence represents an effective mechanism for repeated and rapid adaptation during the lifetime. Notably, the adolescent phase may provide a last chance for correction if the future environment deviates from that predicted in earlier phases.
Collapse
Affiliation(s)
- Norbert Sachser
- Department of Behavioural Biology, University of Muenster, Badestrasse 13, 48149 Muenster, Germany.
| | | | | |
Collapse
|
10
|
Lürzel S, Kaiser S, Krüger C, Sachser N. Inhibiting influence of testosterone on stress responsiveness during adolescence. Horm Behav 2011; 60:691-8. [PMID: 21983230 DOI: 10.1016/j.yhbeh.2011.09.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 08/26/2011] [Accepted: 09/11/2011] [Indexed: 12/17/2022]
Abstract
The maturation of the hypothalamo-pituitary-adrenal (HPA) axis is a key-component of the changes that occur during adolescence. In guinea pigs, HPA responsiveness during late adolescence depends strongly on the quantity and quality of social interactions: Males that lived in a large mixed-sex colony over the course of adolescence exhibit a lower stress response than males that were kept in pairs (one male/one female). Since colony-housed males have higher testosterone (T) levels than pair-housed males, and inhibiting effects of T on HPA function are well known, we tested the hypothesis that the decrease in stress responsiveness found in colony-housed males is due to their high T concentrations. We manipulated T levels in two experiments: 1) gonadectomy/sham-gonadectomy of colony-housed males (which usually have high T levels), 2) application of T undecanoate/vehicle to pair-housed males (which usually have low T levels). As expected, gonadectomized males showed a significantly increased stress response in comparison with sham-gonadectomized males, and T-injected males had a significantly lower stress response than vehicle-injected males. Both experiments thus confirm an inhibiting effect of T on HPA responsiveness during adolescence, which can mediate the influence of social interactions. The reduction in stress responsiveness is hypothesized to have a biologically adaptive value: A sudden increase in glucocorticoid concentrations can enhance aggressive behavior. Thus, pair-housed males might be adapted to aggressively defend their female ('resource defense strategy'), whereas colony-housed males display little aggressive behavior and are capable of integrating themselves into a colony ('queuing strategy').
Collapse
Affiliation(s)
- Stephanie Lürzel
- Department of Behavioural Biology, University of Münster, Badestraße 13, 48149 Münster, Germany.
| | | | | | | |
Collapse
|
11
|
Lürzel S, Kaiser S, Sachser N. Social interaction decreases stress responsiveness during adolescence. Psychoneuroendocrinology 2011; 36:1370-7. [PMID: 21493009 DOI: 10.1016/j.psyneuen.2011.03.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 02/24/2011] [Accepted: 03/18/2011] [Indexed: 01/31/2023]
Abstract
Adolescence is the transition from infancy to adulthood and encompasses major changes in the brain, the endocrine systems, and behavior. During late adolescence, male guinea pigs living in mixed-sex colonies exhibit a lower cortisol (C) response to novelty compared with animals in other ages and housing conditions. It was hypothesized that this reduction in stress responsiveness is induced by a high amount of social interactions in the colonies. In a previous study (Lürzel et al., 2010), late adolescent colony-housed males (CM) were compared with similarly aged males that were housed in heterosexual pairs (PM) as well as with males that were also housed in pairs, but regularly received additional social stimulation by allowing them ten times to interact with unfamiliar adult animals of both sexes for 10 min (SM). CM had a significantly lower stress response than PM, with SM being intermediate and not significantly different from either of the other groups. We assumed that the amount of social stimulation in SM was insufficient in order to achieve a significant reduction of stress responsiveness compared with PM. For the present study, we hypothesized that with a higher amount of social stimulation, a significant difference in stress responsiveness between PM and SM becomes apparent during late adolescence. Thus, PM were again compared with SM that, this time, had received twice as much social stimulation as in the previous study. As a result, stress responsiveness was indeed significantly lower in SM than in PM during late adolescence. Thus, a high amount of social interactions during the course of adolescence leads to a decreased stress responsiveness. Furthermore, SM showed an increase in testosterone (T) levels caused by social stimulation. We hypothesize that the reduction in stress responsiveness is brought about by high T levels that organize central neural structures over the course of adolescence.
Collapse
Affiliation(s)
- Stephanie Lürzel
- Department of Behavioural Biology, University of Münster, Badestraße 13, 48149 Münster, Germany.
| | | | | |
Collapse
|
12
|
Sachser N, Hennessy MB, Kaiser S. Adaptive modulation of behavioural profiles by social stress during early phases of life and adolescence. Neurosci Biobehav Rev 2010; 35:1518-33. [PMID: 20854842 DOI: 10.1016/j.neubiorev.2010.09.002] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 08/12/2010] [Accepted: 09/10/2010] [Indexed: 01/19/2023]
Abstract
The development of individual behavioural profiles can be powerfully influenced by stressful social experiences. Using a comparative approach, we focus on the role of social stressors for the modulation of behavioural profile during early phases of life and adolescence. For gregarious species, the stability of the social environment in which the pregnant and lactating female lives is of major importance for foetal brain development and the behavioural profile of the offspring in later life. Social instability during these critical periods of development generally brings about a behavioural and neuroendocrine masculinisation in daughters and a less pronounced expression of male-typical traits in sons. Moreover, when mothers live in a socially threatening world during this time, anxiety-like behaviour of their offspring often is elevated in adulthood. These effects of the social environment are likely to be mediated by maternal hormones and/or maternal behaviour. In addition, they can be modulated significantly by offspring genotype. We favour the hypothesis that the behavioural effects of social stress during this phase of life are not necessarily "pathological" (nonadaptive) consequences or constraints of adverse social conditions. Rather, mothers could be adjusting the offspring to their environment in an adaptive way. Adolescence is another period in which behavioural development is particularly susceptible to social influences. There is some evidence that stressful social events experienced at this time alter and canalize behaviour in an adaptive fashion, so that earlier influences on behavioural profile development can be complemented and readjusted, if necessary, to meet current environmental conditions. In terms of underlying neuroendocrine mechanism, a central role for the interaction of testosterone and stress hormones is suggested. In summary, the modulation of behavioural profiles by social stress from the prenatal phase through adolescence appears to represent an effective mechanism for repeated and rapid adaptation.
Collapse
Affiliation(s)
- Norbert Sachser
- Department of Behavioural Biology, University of Muenster, Badestrasse 9, 48149 Muenster, Germany.
| | | | | |
Collapse
|
13
|
Lürzel S, Kaiser S, Sachser N. Social interaction, testosterone, and stress responsiveness during adolescence. Physiol Behav 2010; 99:40-6. [DOI: 10.1016/j.physbeh.2009.10.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 09/25/2009] [Accepted: 10/06/2009] [Indexed: 11/16/2022]
|
14
|
Bauer B, Womastek I, Dittami J, Huber S. The effects of early environmental conditions on the reproductive and somatic development of juvenile guinea pigs (Cavia aperea f. porcellus). Gen Comp Endocrinol 2008; 155:680-5. [PMID: 17977535 PMCID: PMC3108884 DOI: 10.1016/j.ygcen.2007.09.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Revised: 09/19/2007] [Accepted: 09/21/2007] [Indexed: 11/16/2022]
Abstract
Little is known about the effects of the early environment on the development of non-seasonally reproducing species like the domestic guinea pig (Cavia aperea f. porcellus). Although guinea pigs reproduce throughout the year, there is evidence for environmental sensitivity of their reproductive physiology. To investigate the sensitivity of juvenile body weight and puberty to differences in the prenatal and early postnatal environment, subjects were exposed to either of two experimental conditions mimicking seasonal variation: a long photoperiod with 25 degrees C ambient temperature ("LD/25 degrees C"), or a short photoperiod with 15 degrees C ("SD/15 degrees C"). Mean body weight of F1-males from LD/25 degrees C-conditions was higher than that of SD/15 degrees C-males during the whole pubertal period, although the difference was significant only during the early growth phase. Testosterone concentrations also differed significantly between the two treatment groups, pointing to an earlier pubertal onset in LD/25 degrees C- than SD/15 degrees C-males. In F1-females, treatment effects on body weight or age at first estrus were absent. This indicates that the somatic and reproductive development is more sensitive to early photoperiod and temperature conditions in male than female guinea pigs, and that other environmental factors may also play a crucial role for reproductive maturation in this species.
Collapse
Affiliation(s)
- Barbara Bauer
- Research Institute of Wildlife Ecology, University of Veterinary Medicine, Savoyenstrasse 1, A-1160 Vienna, Austria.
| | | | | | | |
Collapse
|
15
|
Kaiser S, Harderthauer S, Sachser N, Hennessy MB. Social housing conditions around puberty determine later changes in plasma cortisol levels and behavior. Physiol Behav 2007; 90:405-11. [PMID: 17196999 DOI: 10.1016/j.physbeh.2006.10.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 09/29/2006] [Accepted: 10/10/2006] [Indexed: 10/23/2022]
Abstract
A recent study found that male guinea pigs raised in large, mixed age/sex groups exhibited an unexpected suppression of their cortisol response at 4 mo of age. The present study examined the effect of social experience around the time of puberty on cortisol response suppression and social behavior at 4 mo of age. Males reared in large, mixed age/sex groups were either pair-housed with a female or moved to another large colony at 55 days of age. When tested at 4 mo, pair-housed males exhibited much higher levels of courtship and sexual behavior than did colony-housed males, and a shorter latency to begin courtship when with an unfamiliar adult female. In addition, pair-housed males showed much higher levels of agonistic behavior and a shorter latency to escalated aggression with an unfamiliar adult male. Pair-housed males also had lower basal cortisol concentrations and exhibited a greater increment in cortisol levels when isolated in a novel cage than did colony-housed males. Finally, pair-housed males showed a smaller increment in cortisol levels when with the stimulus female or male than when isolated, but colony-housed males did not. The findings demonstrate that social housing conditions around the time of puberty can have pervasive effects on social behavior and hypothalamic-pituitary-adrenal (HPA) activity in 4-mo-old males. Further, these findings are consistent with the notion that changes in HPA activity contribute to social behavior development beyond the time of sexual maturity.
Collapse
Affiliation(s)
- Sylvia Kaiser
- Department of Behavioural Biology, University of Muenster, Badestrasse 9, 48149 Muenster, Germany
| | | | | | | |
Collapse
|
16
|
Hennessy MB, Hornschuh G, Kaiser S, Sachser N. Cortisol responses and social buffering: a study throughout the life span. Horm Behav 2006; 49:383-90. [PMID: 16242132 DOI: 10.1016/j.yhbeh.2005.08.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 08/09/2005] [Accepted: 08/26/2005] [Indexed: 11/23/2022]
Abstract
The ability of specific adult females to moderate plasma cortisol responses throughout the life span was examined in male guinea pigs maintained in large mixed age/sex groups. At four critical life stages of social development (preweaning, periadolescent, sexually but not socially mature, and sexually and socially mature), the same male guinea pigs were exposed to the stressor of exposure to a novel environment for 4 h while either alone, with an unfamiliar adult female, or with a favored adult female, as based on objective criteria from behavioral observation at that life stage. In preweaning males (9-19 days of age), the favored female (biological mother), but not an unfamiliar female, reduced the cortisol response in the novel environment. In periadolescents (49-61 days), an unfamiliar female, but not the favored female, buffered the cortisol response. At the sexually but not socially mature stage (114-126 days), the cortisol response to novelty was depressed in all conditions, and not affected by either female. At the sexually and socially mature stage (270-330 days), the favored female, but not the unfamiliar female, moderated cortisol levels. These results corroborate previous findings in infants and full adults, demonstrate marked age-specific changes in the ability of females to buffer hypothalamic-pituitary-adrenal responses, and identify a heretofore undescribed period of cortisol response suppression in maturing male guinea pigs. The changing pattern of social buffering during the life span described here for the guinea pig might represent a more general pattern for males of other group-living mammals.
Collapse
Affiliation(s)
- Michael B Hennessy
- Department of Psychology, Wright State University, Dayton, OH 45431, USA
| | | | | | | |
Collapse
|
17
|
Trillmich F, Laurien-Kehnen C, Adrian A, Linke S. Age at maturity in cavies and guinea-pigs (Cavia aperea and Cavia aperea f. porcellus): influence of social factors. J Zool (1987) 2006. [DOI: 10.1111/j.1469-7998.2005.00015.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
18
|
Kaiser S, Kruijver FPM, Swaab DF, Sachser N. Early social stress in female guinea pigs induces a masculinization of adult behavior and corresponding changes in brain and neuroendocrine function. Behav Brain Res 2003; 144:199-210. [PMID: 12946610 DOI: 10.1016/s0166-4328(03)00077-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study was undertaken to investigate, in guinea pigs, the effects of pre- and early postnatal social stress on the functioning of hormonal-, autonomic-, behavioral-, and limbic-brain systems. Dams had either lived in groups with a constant composition (i.e. stable social environment) or in groups with changing compositions, that means every 3 days two females were transferred from one group to another (i.e. unstable social environment). The subjects studied were female offspring of dams who had either lived in a stable social environment during pregnancy and lactation (i.e. control daughters, CF) or in an unstable social environment during this period of life (i.e. early stressed daughters, SF). After weaning, each five groups of CF and SF, consisting of two females each, were established. The spontaneous behavior of the females was recorded, blood samples were taken to determine cortisol, testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate and estrogen levels, the adrenals were prepared to determine tyrosinehydroxylase (TH) activities and the brains to investigate the distribution of sex hormone receptors. SF showed not only a behavioral and endocrine masculinization, but also an upregulation of androgen receptor and estrogen receptor-alpha in the medial preoptic area and the nucleus arcuatus of the hypothalamus, the nucleus paraventricularis of the thalamus, and the CA1 region of the hippocampus. These findings corresponded with distinctly elevated serum-concentrations of testosterone and increased activities of the adrenal TH. In conclusion, early social stress caused by an unstable social environment induces in female guinea pigs a permanent behavioral masculinization that is accompanied by changes in the endocrine and autonomic system as well as by changes in the distribution of sex hormone receptors in the limbic system.
Collapse
Affiliation(s)
- Sylvia Kaiser
- Department of Behavioural Biology, University of Münster, Badestr. 9, D-48149 Münster, Germany.
| | | | | | | |
Collapse
|
19
|
Hennessy MB, Maken DS, Graves FC. Presence of mother and unfamiliar female alters levels of testosterone, progesterone, cortisol, adrenocorticotropin, and behavior in maturing Guinea pigs. Horm Behav 2002; 42:42-52. [PMID: 12191646 DOI: 10.1006/hbeh.2002.1794] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the guinea pig is characterized by precocial physical development and minimal active maternal care, studies suggest the presence of the mother can influence neuroendocrine and behavioral activity of offspring even well beyond weaning. Previous results may have been influenced by the procedure of housing weaned subjects with the mother to within 2 days of testing. The present study examined approximately 40-day-old guinea pigs housed apart from the mother for 0 (not rehoused), 2, or 10 days. Rehousing without the mother led to elevations in plasma testosterone (measured in males), progesterone (measured in females), cortisol, and adrenocorticotropin (ACTH) (both measured in males and females). Offspring housed without the mother for 10 days had the highest progesterone, cortisol, and ACTH levels. Testosterone elevations were observed in 2-day-, but not 10-day-, rehoused animals. Regardless of rehousing condition, 60 min isolation in a novel test cage elevated progesterone, cortisol, and ACTH, and reduced testosterone. These effects were all moderated if the subject was tested with the mother or another female. Sexual behavior toward the mother was observed frequently, but only in males housed apart from her prior to testing. Overall, males and females that had been housed apart from the mother interacted with her as they would an unfamiliar female. Our results corroborate previous findings, suggest the effect of housing apart from the mother on male testosterone is transitory, and indicate that continuous housing with the mother past weaning suppresses circulating progesterone in females and cortisol and ACTH in both sexes.
Collapse
Affiliation(s)
- Michael B Hennessy
- Department of Psychology, 335 Fawcett Hall, Wright State University, Dayton, Ohio 45435, USA.
| | | | | |
Collapse
|
20
|
Kaiser S, Sachser N. Social stress during pregnancy and lactation affects in guinea pigs the male offsprings' endocrine status and infantilizes their behaviour. Psychoneuroendocrinology 2001; 26:503-19. [PMID: 11337134 DOI: 10.1016/s0306-4530(01)00009-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study investigated the influence of the social environment during pregnancy and lactation on the male offsprings' endocrine parameters and behaviour in guinea pigs. The subjects studied were sons whose mothers had either lived in a stable social environment during pregnancy and lactation or in an unstable social environment during this period of life. The stable social environment was made by keeping the group composition (one male, five females) constant; in the unstable social environment situation every third day, two females from different groups were exchanged. After weaning, seven groups of sons, whose mothers had lived in an unstable social environment and seven groups of sons, whose mothers had lived in a stable social environment, consisting of two males each, were established. From their 20th through their 100th day of age the spontaneous behaviour of the males was recorded in their home cages. On the endocrine level, cortisol- and testosterone-concentrations in serum as well as adrenal tyrosine hydroxylase activities were determined. Sons, whose mothers had lived in an unstable social environment, showed significantly higher amounts of resting with bodily contact than sons, whose mothers had lived in a stable social environment. Additionally, they displayed this behaviour to an older age than the latter sons. Further on, sons, whose mothers had lived in an unstable social environment, displayed significantly higher frequencies of courtship behaviour than sons, whose mothers had lived in a stable social environment, which was integrated into play behaviour. These behavioural data point to an infantilization of sons, whose mothers had lived in an unstable social environment. The behavioural patterns corresponded with a delayed development of the hypothalamo-pituitary-adrenocortical-axis and a lower activity of the sympathetic-adrenomedullary-system compared to sons whose mothers had lived in a stable social environment. Testosterone did not differ between both categories of males. Thus, the instability of the social environment during pregnancy and lactation had distinct and not yet described effects on the behaviour and endocrine system of the male offspring.
Collapse
Affiliation(s)
- S Kaiser
- University of Münster, Institute for Neuro- and Behavioural Biology, Department of Behavioural Biology, Badestr. 9, 48149, Münster, Germany.
| | | |
Collapse
|
21
|
Hennessy MB. Social influences on endocrine activity in guinea pigs, with comparisons to findings in nonhuman primates. Neurosci Biobehav Rev 1999; 23:687-98. [PMID: 10392660 DOI: 10.1016/s0149-7634(99)00013-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Guinea pigs exhibit a rich and varied social organization. Studies in recent years have demonstrated that social stimuli have widespread neuroendocrine effects in guinea pigs. Here, effects on the hypothalamic-pituitary-adrenal, adrenal medullary/sympathetic, and hypothalamic-pituitary-gonadal systems of both adult and developing guinea pigs are reviewed. These systems respond to various social variables, or factors that affect social variables, including: separation from attachment objects, housing conditions, changes in housing, the familiarity of the environment in which social interactions occur, foraging conditions, surrogate-rearing, agonistic interactions, and the establishment of dominance rank. Similarities and differences between these findings and those in nonhuman primates are discussed. It is argued that the guinea pig is well suited for the study of socioendocrine effects throughout the life span, and can provide a valuable complement to nonhuman primate research in this area.
Collapse
Affiliation(s)
- M B Hennessy
- Department of Psychology, Wright State University, Dayton, OH 45435, USA.
| |
Collapse
|
22
|
Wolfer DP, Lipp HP. Evidence for physiological growth of hippocampal mossy fiber collaterals in the guinea pig during puberty and adulthood. Hippocampus 1995; 5:329-40. [PMID: 8589796 DOI: 10.1002/hipo.450050406] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
By means of Timm's procedure and computer-assisted morphometry, the left and right hippocampi of 69 hybrid guinea pigs from nine age levels (P5, P10, P20, P40, P80, P160, P320, and P610, and P1100) were analyzed for postnatal growth of recurrent hippocampal mossy fiber collaterals (RMFC) terminating below, within, and above the dentate granule cell layer. Postnatal growth of RMFCs showed, in both sexes, a first peak at P40, with stainable mossy fiber boutons covering the cell bodies of large neurones, some of which were reminiscent of basket cells. No significant changes of the density of mossy fiber collaterals were noticed from P40 to P160. At P320 a remarkable expansion of RMFCs was noted in a few animals, and by P610 all animals showed highly proliferated RMFCs which densely covered cell bodies and dendrites of target cells. The oldest group (P1100) showed an equal or slightly lowered density of RMFCs. We conclude that the growth of recurrent mossy fiber collaterals occurs in two spurts. The first completes just before sexual maturity. The second spurt occurs in the mid-life period, between P160 and P610.
Collapse
Affiliation(s)
- D P Wolfer
- Institute of Anatomy, University of Zürich-Irchel, Switzerland
| | | |
Collapse
|
23
|
Sachser N, Lick C, Stanzel K. The environment, hormones, and aggressive behaviour: a 5-year-study in guinea pigs. Psychoneuroendocrinology 1994; 19:697-707. [PMID: 7938365 DOI: 10.1016/0306-4530(94)90051-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This paper summarizes persistent consequences of varying rearing and testing conditions on intermale aggression, endocrine responses, and body weight (BW) in guinea pigs. Pairs of unfamiliar males were placed in chronic confrontations for 3-50 days in 2 m2 enclosures. Their behaviour was recorded in more than 1000 h of observation time. About 900 samples were assayed for plasma glucocorticoid (GC), testosterone (T), and norepinephrine (NE) before and at different times after the beginning of the confrontations. The males were reared either in large mixed-sex colonies (CRM) or with a single female (FRM). When FRM males were confronted, high levels of aggressive behaviour occurred and high degrees of stress were found in losers, especially when the environment was familiar and a female was present. In contrast, CRM males confronted in the same situation, but in a nonaggressive way, showed no changes in GC, NE, and BW. These differences between FRM and CRM developed around puberty. A 50-min agonistic experience with an unfamiliar male around this time shifted the subsequent adult behaviour of a FRM to a CRM pattern. These findings suggest a causal relationship between social experiences occurring around puberty, subsequent behaviour as adults, and degree of stress in chronic social encounters.
Collapse
Affiliation(s)
- N Sachser
- Universität Bayreuth, Lehrstuhl für Tierphysiologie, Deutschland
| | | | | |
Collapse
|
24
|
Abstract
The study examined the effect of age on the ability to arrange with unfamiliar conspecifics in differentially reared male guinea pigs. The experiments were conducted with 50-, 90-, 150-, and 210-240-day-old-males, which either had been reared in large colonies (CRM) or each with a single female (FRM). In each age class, seven pairs of unfamiliar CRM and seven pairs of unfamiliar FRM were placed in chronic confrontations for 6-10 days in the presence of an unfamiliar female in 2 m2 enclosures. Body weights were determined directly before and 52 h, 124 h, and 220 h after the onset of the experiments. CRM showed no substantial losses in body weights irrespective of whether the experiments were conducted before, around, or after sexual maturity (which is achieved at 2-3 months of age). In contrast pairs of FRM arranged without problems only at 50 days of age. Around puberty, social stress distinctly increased, and 2 and 4-5 months later the confrontations even had to be ceased after 6 days, because losers extremely decreased in body weights. It is concluded that in male guinea pigs the time around sexual maturity is crucial for the development of social skills necessary to arrange with unfamiliar conspecifics in a nonstressful way.
Collapse
Affiliation(s)
- N Sachser
- Department of Animal Physiology, University of Bayreuth, Germany
| |
Collapse
|
25
|
Bergvall AH, Vega Matuszczyk J, Dahlöf LG, Hansen S. Peripheral anosmia attenuates female-enhanced aggression in male rats. Physiol Behav 1991; 50:33-40. [PMID: 1946728 DOI: 10.1016/0031-9384(91)90494-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
It is well established that male rats with prior access to sexually active females show enhanced offensive aggression toward unfamiliar male intruders. The present study assessed the importance of the sense of smell for this facilitatory effect. It was found in 2 independent experiments that anosmia, induced peripherally by surgically removing the olfactory epithelium and cutting the olfactory nerves, reduced baseline levels of offensive aggression and significantly attenuated the female-enhanced aggression effect. It was also found that sexual performance of anosmic rats was context-dependent, in that it was more impaired in the homecage environment than in standard observation cages. In contrast to sham-operated males, the experimental animals showed no preference for estrous over anestrous females in a mate choice test. Anosmic males did not appear more fearful than controls, as assessed in a hyponeophagia test, but they showed less exploratory behavior (rearing and head-dipping) in the hole-board test, and less rearing activity in automated activity boxes.
Collapse
Affiliation(s)
- A H Bergvall
- Department of Psychology, University of Göteborg, Sweden
| | | | | | | |
Collapse
|
26
|
Abstract
This study examined the effect of varying rearing and testing conditions on guinea pig aggression, courting behavior, endocrine responses and body weight. Pairs of 7-8-month-old males were placed in chronic confrontations for 6-50 days in 2 m2 enclosures. Social behavior was recorded with a total of 882 h observation time. Body weight as well as plasma glucocorticoid, testosterone and norepinephrine titers were determined for each male 20 h before, and 4, 52 and 124 h after, the onset of the chronic encounters. Three experiments were conducted: in Experiment I, 7 pairs of males, each male raised singly with one female (FRM), were confronted in the presence of an unfamiliar female, in Experiment II, 6 pairs of FRM were confronted with no female present, and in Experiment III, 7 pairs of males which were raised in different large colonies were confronted in the presence of an unfamiliar female. In Experiment II and III low levels of aggression, no distinct endocrine changes and no indications of physical injury occurred in winners or losers, whereas in Experiment I high levels of aggression and courting behavior, extreme increases in glucocorticoid titers and distinct decreases in body weights were found in both males. Losers, however, were affected to a much greater extent than winners. These findings suggest that in guinea pigs a causal relationship exists between social rearing conditions, behavior as adults and degree of social stress in chronic encounters.
Collapse
Affiliation(s)
- N Sachser
- Department of Animal Physiology, University of Bayreuth, Germany
| | | |
Collapse
|
27
|
Haemisch A. Coping with social conflict, and short-term changes of plasma cortisol titers in familiar and unfamiliar environments. Physiol Behav 1990; 47:1265-70. [PMID: 2395931 DOI: 10.1016/0031-9384(90)90381-d] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Each of 27 male guinea pigs was confronted with a strange opponent a) in its familiar home cage (CHC) and b) in the unfamiliar cage of the opponent (CSC) and was c) exposed to an unfamiliar open-field area without a conspecific present (OFA). The behavior displayed during confrontations was recorded in detail and plasma-cortisol-titers (PCT) were measured immediately before and after each test. The main findings were: 1) PCT increased significantly in response to the tests carried out in unfamiliar environments (OFA and CSC) compared with the response to the home-cage confrontation. 2) In both confrontation tests "offensive" males could be distinguished from "defensive" males according to marked differences in their agonistic behavior. Offensive males approached and threatened their opponents. Defensive males retreated and did not perform elements of threat behavior. 3) Offensive males showed significantly lower increases in PCT than defensive males in the home-cage confrontations. Increases in PCT did not differ significantly between the two categories of male in the strange-cage confrontations. The results show a) that different intensities of adrenocortical responses depend on the behavioral coping pattern and b) that this behavioral effect can be masked by environmental factors.
Collapse
Affiliation(s)
- A Haemisch
- Department of Ethology, University of Bielefeld, West Germany
| |
Collapse
|
28
|
Abstract
Confrontation studies between eight pairs of two 7-8 months old male guinea pigs, each raised with one female from their 30th day of age, were conducted in an enclosure of 2 m2 in the presence of an unfamiliar female. The opponents were chronically kept together for up to 8 days. When they were not separated after 52 hr, one or (in 1 case) both males fell into a comatose state and died 5-8 days after the onset of the confrontation. Four hr after the onset of the confrontations both opponents showed significantly increased plasma glucocorticoid (CS) titers. At this time as well as 24 hr earlier, prospective winners (PW) and prospective losers (PL) did not yet differ in any physiological parameter measured. Forty-eight hr later, PW were characterized by a low body weight loss, low CS, high testosterone (T) and elevated plasma-catecholamine (CA) values. In contrast, PL showed a high body weight loss, very high CS titers, low T-titers and more elevated CA values than PW. Despite these highly significant differences in physiological parameters, PL and PW did not yet differ in the frequency of any agonistic behavioral element recorded. Seventy-two hr after the onset of the chronic cohabitation, losers began to behave more and more passive, they ceased feeding and drinking and were less and less involved in social interactions. The physiological differences between winners and losers intensified.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- N Sachser
- Department of Animal Physiology, University of Bayreuth, West Germany
| | | |
Collapse
|