Laura Pasquier, Violette Wallart, Séverine Devers, Joël Meunier, Charlotte Lécureuil
{"title":"Juvenile hormone and maternal egg care in the European earwig (part I): Manipulation of JH, agonist, and precocene fails to induce the onset of egg care.","authors":"Laura Pasquier, Violette Wallart, Séverine Devers, Joël Meunier, Charlotte Lécureuil","doi":"10.1016/j.yhbeh.2025.105841","DOIUrl":"https://doi.org/10.1016/j.yhbeh.2025.105841","url":null,"abstract":"<p><p>Parental care is a crucial behaviour in animals. Yet the mechanisms regulating its initiation remain poorly understood, particularly in insects. Juvenile hormone (JH) is widely recognized as a key hormonal regulator in insects that influences a broad diversity of physiological and behavioural traits, including parental care after oviposition. However, its role in triggering the onset of egg care remains unexplored. To address this, we experimentally manipulated JH levels in 194 pre-ovipositing European earwig females and tested whether they initiated care towards foreign eggs. Contrary to our predictions, topical application or injection of JH, methoprene (a JH analogue), precocene (a JH production inhibitor) or acetone (control) at varying doses failed to induce egg care or to prevent egg cannibalism. This rejection of foreign eggs was not due to experimental stress, as positive control females that had previously laid eggs cared for new foreign eggs, even after acetone exposure. These results demonstrate that neither the presence or absence of JH nor the mere presence of eggs is sufficient to induce maternal care in pre-ovipositing females. Instead, our findings suggest that additional signals beyond JH modulation and/or alternative hormonal pathways may be critical for initiating care behaviours in earwigs. Overall, this study advances our understanding of the complex regulatory mechanisms underlying parental care and the multifaceted role of JH in insect behaviour.</p>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"105841"},"PeriodicalIF":2.4,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145299794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Navina D. Liebermann-Lilie , Benedikt Schniedermeyer , Anabel Kröhnert , Sepand Riyahi , Sylvia Kaiser , Tim Schmoll , Peter Korsten
{"title":"Adjustment of paternal care in response to experimental variation in extra-pair mating opportunity in male zebra finches","authors":"Navina D. Liebermann-Lilie , Benedikt Schniedermeyer , Anabel Kröhnert , Sepand Riyahi , Sylvia Kaiser , Tim Schmoll , Peter Korsten","doi":"10.1016/j.yhbeh.2025.105834","DOIUrl":"10.1016/j.yhbeh.2025.105834","url":null,"abstract":"<div><div>Extra-pair paternity is prevalent in socially monogamous bird species with biparental care. Male extra-pair matings may coincide with paternal care provisioned to within-pair offspring. This may lead to a trade-off between obtaining additional fertilizations and securing offspring growth and survival through paternal care. In this pre-registered study, we manipulated the social environment of zebra finches to investigate how males trade off extra-pair mating versus providing paternal care. We compared paternal care provision between a social environment where two pairs bred together in a cage—resulting in an opportunity for extra-pair mating (Double-pair group)—to one with single breeding pairs (Single-pair group). We additionally measured plasma testosterone and corticosterone to identify hormonal correlates of male behavioral responses. To further increase the opportunity for extra-pair mating for the focal males from the Double-pair group we removed the male of the non-focal pair during chick rearing by the focal males. Contrary to our predictions, Double-pair males incubated more than Single-pair males. While we found substantial extra-pair paternity in the Double-pair group after removal of the non-focal males, male brood provisioning, chick growth and survival, and testosterone levels were not affected by the experimental increase in male extra-pair mating opportunity. Corticosterone levels were higher in Single-pair males between the first and replacement clutch. Refuting common assumptions, our findings provide no experimental evidence for a trade-off between extra-pair mating and paternal care. Males were able to pursue extra-pair fertilizations while they simultaneously secured the growth and survival of their within-pair offspring.</div></div>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"Article 105834"},"PeriodicalIF":2.4,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juliane Damm , Pedro A.D. Dias , Ariadna Rangel-Negrín , Colleen M. Schaffner , Fabrizio Dell'Anna , Filippo Aureli
{"title":"Endocrine and behavioral responses to ecological and social challenges in wild Geoffroy's spider monkeys","authors":"Juliane Damm , Pedro A.D. Dias , Ariadna Rangel-Negrín , Colleen M. Schaffner , Fabrizio Dell'Anna , Filippo Aureli","doi":"10.1016/j.yhbeh.2025.105824","DOIUrl":"10.1016/j.yhbeh.2025.105824","url":null,"abstract":"<div><div>To maintain homeostasis during external and internal challenges, vertebrates activate allostatic systems, such as the hypothalamic-pituitary-adrenal (HPA) axis. Additionally, animals can use behavioral responses to address such challenges, which may result in the reduction of allostatic processes. We assessed whether HPA activation is influenced by subgroup formation patterns during ecological and social challenges. We selected Geoffroy's spider monkeys (<em>Ateles geoffroyi</em>) as study subjects, because they are characterized by a high degree of fission-fusion dynamics. We expected spider monkeys to address challenges by being in smaller subgroups when food availability is lower, in larger subgroups when perceived predation risk is higher, and either in larger subgroups or in proximity of more individuals when the likelihood of between-group encounters is higher. For 20 months, we collected behavioral data and fecal samples from 30 wild adult and subadult spider monkeys at the Otoch Ma'ax Yetel Kooh reserve in the Yucatán peninsula, Mexico, and assessed food availability in their home range. In support of our predictions, fecal glucocorticoid metabolite (fGCM) concentrations were negatively associated with food availability, and they were lower when in smaller subgroups than in larger subgroups during low food availability. Fecal GCM concentrations were positively associated with alarm call rates and were lower when in larger subgroups than when in smaller subgroups during high perceived predation risk. We found no evidence for an association between fGCM concentrations and the likelihood of between-group encounters. Overall, subgroup formation patterns interact with HPA activity to successfully address ecological challenges in wild Geoffroy's spider monkeys. Our study highlights the importance of assessing ecological challenges and behavioral responses when interpreting HPA activation in the wild.</div></div>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"Article 105824"},"PeriodicalIF":2.4,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Chronic social isolation, crowding, and instability distinctly impact reproductive function in adult female Wistar rats","authors":"Marilou Poitras , Adèle Labonté , Aliya F. Qureshi , Cassandra Blackburn , Zoé M.I. Gracovetsky , Rutaaba Fasih , Hélène Plamondon","doi":"10.1016/j.yhbeh.2025.105835","DOIUrl":"10.1016/j.yhbeh.2025.105835","url":null,"abstract":"<div><div>Social stressors represent highly relevant stress models which remain understudied in females. Concordantly, little is known of the impact of different types of social stress on female reproductive functioning, despite close interactions between the hypothalamic-pituitary-adrenal (HPA) axis and hypothalamic-pituitary-gonadal (HPG) axis. This study provides a comprehensive assessment of reproductive functioning in female rats following exposure to three social stress paradigms. 112 regularly cycling adult female Wistar rats were exposed to 21 days of isolation, crowding, social instability, control housing (daily cage changes) or regular housing. Rats were then euthanized (in proestrus or diestrus) or underwent paced-mating and fertility assessments. Estrous cyclicity, uterine horn weight, hypothalamic expression of kisspeptin (Kiss1), gonadotropin-inhibitory hormone (GnIH), estrogen receptors alpha (ERα), and glucocorticoid receptors (GR), serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), progesterone (P4), and corticosterone (CORT), as well as ovarian follicle counts were assessed. Findings show isolation to increase hopping behaviors, decrease early follicle counts, uterine weight, and GnIH, as well as increase FSH levels. In crowded rats, expression of GnIH and ERα were reduced, paralleled by fewer days spent in proestrus and increased hopping behaviors. Following instability, rats presented decreased estrous cyclicity, reduced uterine weight, and diminished ovarian reserve, despite minimal changes at the hypothalamic level. Paced mating exposure increased CORT in all groups except instability and crowding. Overall, social stressors presented distinct consequences on reproduction, highlighting their relevance as stress models and the importance of gaining a better understanding of social stress-induced reproductive dysfunction in females.</div></div>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"Article 105835"},"PeriodicalIF":2.4,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A.K. Janse van Vuuren , T. Süess , Kyle Finn , N. Hagenah , A. Ganswindt , D.W. Hart , N.C. Bennett
{"title":"Hormonal lockdown: How mole-rat societies enforce infertility in helpers","authors":"A.K. Janse van Vuuren , T. Süess , Kyle Finn , N. Hagenah , A. Ganswindt , D.W. Hart , N.C. Bennett","doi":"10.1016/j.yhbeh.2025.105836","DOIUrl":"10.1016/j.yhbeh.2025.105836","url":null,"abstract":"<div><div>Reproductive suppression is a defining feature of cooperative breeding, yet the hormonal mechanisms regulating infertility in non-breeding individuals remain poorly understood. This study examines associations between circulating prolactin (PRL) and faecal metabolites of androgens (fAM), glucocorticoids (fGCM), and progesterone (fPM) in relation to socially induced infertility in two closely related cooperatively breeding mole-rat subspecies: the highveld (<em>Cryptomys hottentotus pretoriae</em>) and Natal mole-rat (<em>C. hottentotus natalensis</em>). Our results reveal a fundamental dichotomy in reproductive suppression strategies. Highveld mole-rats exhibited seasonally elevated circulating PRL in non-breeders during the dry season, coinciding with reduced pituitary responsiveness to exogenous gonadotropin-releasing hormone (GnRH) and lower gonadal steroid metabolites. These associations are consistent with PRL involvement in physiological suppression of the hypothalamic-pituitary-gonadal (HPG) axis, but causality cannot currently be inferred. In stark contrast, Natal mole-rats showed relatively low and stable PRL levels across reproductive groups and seasons, with breeders exhibiting higher androgen and progesterone metabolites compared to non-breeders, a pattern consistent with behavioural suppression through incest avoidance, aggression or social dominance. These findings highlight the adaptive flexibility of cooperatively breeding systems and provide new insights into the hormonal architecture of reproductive suppression. Although the present findings do not establish causality, they delineate key hormonal and behavioural pathways that warrant future investigation.</div></div>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"Article 105836"},"PeriodicalIF":2.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145212500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hormones and BehaviorPub Date : 2025-10-01Epub Date: 2025-08-06DOI: 10.1016/j.yhbeh.2025.105801
Breanna N Harris, Christine M Prater, Ryann Lockwood, Allison Kennedy, M Ghufran Murtuza, James A Carr
{"title":"Tectal CRF receptors modulate the behavioral response of Xenopus laevis to live prey but not visual prey cues.","authors":"Breanna N Harris, Christine M Prater, Ryann Lockwood, Allison Kennedy, M Ghufran Murtuza, James A Carr","doi":"10.1016/j.yhbeh.2025.105801","DOIUrl":"10.1016/j.yhbeh.2025.105801","url":null,"abstract":"<p><p>Tradeoffs between feeding and defensive behaviors are critical for survival, but their physiological underpinnings are not well known. Here, we investigate how a satiety peptide, corticotropin-releasing factor (CRF), acts within a novel location, the visual system (the optic tectum, OT), to modulate multisensory prey detection and the microstructure of feeding behavior. The OT has CRF-producing interneurons and CRF receptors, threat exposure increases OT CRF concentrations, and that CRF acts on receptors in the OT to decrease feeding behavior. We hypothesized that CRF in the OT may impact visual, lateral line, and/or multiple sensory processing to alter feeding. We predicted that OT CRF decreases responses to 1) a purely visual prey cue and 2) a live, multisensory prey item. We microinjected one of four doses of CRF bilaterally into the tecta of newly metamorphosed Xenopus laevis. We then exposed frogs to visual prey cues and then to live, multi-sensory prey (worms). We repeated the behavioral assays after 72 h to determine if any effects were long-lasting. Overall, frogs robustly responded to live and visual prey cues. CRF did not alter behavioral responses to the visual prey cues but did decrease select prey-capture behaviors and increase select avoidance-like behaviors following exposure to live prey. Our results suggest visual processing is not the primary sensory modality impacted by tectal CRF. These data provide a novel (i.e., extrahypothalamic) location for satiety peptide action and link neuroendocrine responses to ecological context of feed/flee tradeoffs.</p>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"175 ","pages":"105801"},"PeriodicalIF":2.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144798956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hormones and BehaviorPub Date : 2025-10-01Epub Date: 2025-08-08DOI: 10.1016/j.yhbeh.2025.105802
Caitlin H Miller, Tess M Reichard, Jay Yang, Brandon Carlson-Clarke, Caleb C Vogt, Melissa R Warden, Michael J Sheehan
{"title":"Pregnancy modulates responses to male odors in house mice.","authors":"Caitlin H Miller, Tess M Reichard, Jay Yang, Brandon Carlson-Clarke, Caleb C Vogt, Melissa R Warden, Michael J Sheehan","doi":"10.1016/j.yhbeh.2025.105802","DOIUrl":"10.1016/j.yhbeh.2025.105802","url":null,"abstract":"<p><p>Pregnancy induces widespread physiological and behavioral changes, yet its impact on social decision-making remains poorly understood. Here, we show that reproductive status modulates female responses to male odors in house mice, revealing striking status-specific behavioral patterns. Estrous females displayed attraction to novel male odors, consistent with a motivation to mate. In contrast, pregnant females exhibited strong aversion - an anticipatory shift likely aimed at avoiding future infanticidal males. This status-dependent approach-avoidance response was recapitulated to the male urinary pheromone darcin, highlighting its robustness as a male signal. These findings suggest that reproductive status modulates odor-driven decision-making, balancing mating opportunities with offspring protection. This shift is likely mediated by hormonal fluctuations such as rising progesterone and estrogen, that act on neural circuits involved in olfaction, threat detection, and social motivation. Behavioral responses were further shaped by the richness and context of social odors, supporting combinatorial processing of urinary pheromones. This aligns with mechanisms such as stud odor imprinting and self-referential matching for inbreeding avoidance. Overall, our results point to anticipatory behavioral adaptations during pregnancy that prepare females for the challenges of motherhood.</p>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"175 ","pages":"105802"},"PeriodicalIF":2.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144811974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sarah A. Blumenthal , Henry W. Kietzman , Karinne E. Cobb , Shannon L. Gourley
{"title":"Stranger-directed consolation-like behavior in mice in a test of social decision making","authors":"Sarah A. Blumenthal , Henry W. Kietzman , Karinne E. Cobb , Shannon L. Gourley","doi":"10.1016/j.yhbeh.2025.105831","DOIUrl":"10.1016/j.yhbeh.2025.105831","url":null,"abstract":"<div><div>In the past decade, investigations into the neurobiology of empathy have been propelled by evidence that rodents are capable of more complex and nuanced social behaviors than previously believed. Several teams have reported that rodents will direct allogrooming and other consolation-like behaviors towards distressed conspecifics, including in situations in which consolation-like behavior was not the explicit focus of a given study. As a case in point, we unexpectedly found in a test of decision making incentivized by social experience that mice display consolation-like allogrooming towards distressed strangers. This observation was somewhat surprising because consolation-like behavior in rodents is often believed to be reserved for familiar conspecifics. Here in this brief report, we reveal that the allogrooming and close social proximity with a distressed stranger that we previously reported was accompanied by elevated sniffing and autogrooming in close proximity to the conspecific – a social contagion-like behavior. Also, these behaviors were not obviously attributable to general hyper-activity. We then describe the conditions in which this constellation of stranger-directed consolation-related behavior was observed, should this information support new research concerning stranger-directed consolation-like behavior.</div></div>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"Article 105831"},"PeriodicalIF":2.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145206157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Blythe A. Corbett , Rachel Calvosa , Jaclyn Tamaroff , Rachael A. Muscatello , Trey McGonigle , Simon Vandekar
{"title":"Examining androgen and estrogen profiles during pubertal development in autistic and neurotypical girls","authors":"Blythe A. Corbett , Rachel Calvosa , Jaclyn Tamaroff , Rachael A. Muscatello , Trey McGonigle , Simon Vandekar","doi":"10.1016/j.yhbeh.2025.105837","DOIUrl":"10.1016/j.yhbeh.2025.105837","url":null,"abstract":"<div><h3>Background</h3><div>Puberty is a normative albeit complex developmental period marked by significant changes in hormonal, physical, and socioemotional functioning. Research has theorized an important role for sex hormones in the etiology and profile of autism spectrum disorder (ASD), especially during developmental periods including puberty. Differences in pubertal onset in autistic compared to neurotypical girls have been reported. Aims examined female participants based on diagnostic (autistic, neurotypical) and hormonal expression (dehydroepiandrosterone (DHEA-S), estradiol, testosterone) in the context of development (puberty, age). Hypotheses included: Hyp 1: autistic compared to neurotypical girls would demonstrate earlier pubertal onset. Hyp 2: DHEA-S and estradiol would be higher in older, more physically mature girls. Hyp 3: Testosterone would be stable.</div></div><div><h3>Methods</h3><div>Participants included females between 6-to-12 years with ASD (<em>N</em> = 112) or typical development (TD, <em>N</em> = 96). Morning salivary samples were collected for hormone assays. Nonlinear least squares and ordinary linear regression models were used.</div></div><div><h3>Results</h3><div>Autistic girls did not show significant evidence of earlier pubertal onset in pubertal stage (<em>p</em> = 0.692). There were no observed diagnostic differences in hormone changes through the pubertal or age range (<em>p</em> = 0.8367, <em>p</em> = 0.0694, <em>p</em> = 0.6812, <em>p</em> = 0.8418, <em>p</em> = 0.7358, & <em>p</em> = 0.1438) sampled. All hormones showed significant changes with puberty and age (<em>p</em> < 0.001).</div></div><div><h3>Conclusions</h3><div>The study examined profiles of females based on diagnostic group and hormonal expression in the context of development. Although group differences were not observed in this cross-sectional study, hormonal differences may emerge as girls progress through puberty. It is vital to track and support autistic girls through this time of change and vulnerability.</div></div>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"Article 105837"},"PeriodicalIF":2.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145199121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Quintin A. Whitman , Amirreza Mirzaei , Samantha C. Lauby , Diptendu Chatterjee , Alison Fleming , Patrick O. McGowan
{"title":"Within-litter variation in maternal care is a key contributor to individual differences in offspring behavior and monoamine neurochemistry in female Long–Evans rats","authors":"Quintin A. Whitman , Amirreza Mirzaei , Samantha C. Lauby , Diptendu Chatterjee , Alison Fleming , Patrick O. McGowan","doi":"10.1016/j.yhbeh.2025.105821","DOIUrl":"10.1016/j.yhbeh.2025.105821","url":null,"abstract":"<div><div>The care that a mother rat provides is essential for the ability of her pups to survive and thrive. Maternal care naturally varies between litters, including among animals with close genetic relatedness. There are also significant differences in behavior even among offspring reared together. Our lab and others have documented stable, naturally occurring individual differences in maternal care received by individual pups within the litter that persist throughout at least the first ten days of postnatal life. In this study, we hypothesized that within-litter variation in maternal care received constitutes a significant source of variation in offspring behavior and neurochemistry in Long-Evans rats. We analyzed measures related to maternal care behavior, offspring anxiety-like and social behaviors, and neurotransmitter levels in specific brain regions after the offspring became mothers themselves. For statistical modeling, we used the coefficient of variation (CV) to standardize and directly compare between- and within-litter variation across a range of behavioral and neurophysiological outcomes. Several variables analyzed showed greater within-litter CVs than between-litter CVs, especially for offspring behavior and levels of the monoamines dopamine, serotonin, and their primary metabolites DOPAC (3,4-dihydroxyphenylacetic acid) and 5-HIAA (5-hydroxyindoleacetic acid) in the nucleus accumbens, ventral tegmental area, medial preoptic area, hippocampus, and prefrontal cortex. Our findings suggest that within-litter variation in maternal care plays a prominent role in behavioral and physiological outcomes. This study provides a methodological advance by demonstrating that within-litter variability often exceeds between-litter variability across maternal, behavioral, and neurochemical domains, challenging a key assumption in experimental designs using littermate controls.</div></div>","PeriodicalId":13001,"journal":{"name":"Hormones and Behavior","volume":"176 ","pages":"Article 105821"},"PeriodicalIF":2.4,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}