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Bove M, Morgese MG, Dimonte S, Sikora V, Agosti LP, Palmieri MA, Tucci P, Schiavone S, Trabace L. Increased stress vulnerability in the offspring of socially isolated rats: Behavioural, neurochemical and redox dysfunctions. Prog Neuropsychopharmacol Biol Psychiatry 2024; 131:110945. [PMID: 38242425 DOI: 10.1016/j.pnpbp.2024.110945] [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: 07/28/2023] [Revised: 12/22/2023] [Accepted: 01/14/2024] [Indexed: 01/21/2024]
Abstract
Stressful events during pregnancy impact on the progeny neurodevelopment. However, little is known about preconceptional stress effects. The rat social isolation represents an animal model of chronic stress inducing a variety of dysfunctions. Moreover, social deprivation during adolescence interferes with key neurodevelopmental processes. Here, we investigated the development of behavioural, neurochemical and redox alterations in the male offspring of socially isolated female rats before pregnancy, reared in group (GRP) or in social isolation (ISO) from weaning until young-adulthood. To this aim, females were reared in GRP or in ISO conditions, from PND21 to PND70, when they were mated. Their male offspring was housed in GRP or ISO conditions through adolescence and until PND70, when passive avoidance-PA, novel object recognition-NOR and open field-OF tests were performed. Levels of noradrenaline (NA), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), glutamate (GLU) and GABA were assessed in the prefrontal cortex (PFC). Moreover, cortical ROS levels were quantified, as well as NF-kB and the NADPH oxidase NOX2 expression, redox status (expressed as GSH:GSSG ratio) and SOD1 amount. A significant decrease of the latency time in the PA was observed in the offspring of ISO females. In the NOR test, while a significant increase in the exploratory activity towards the novel object was observed in the offspring of GRP females, no significant differences were found in the offspring of ISO females. No significant differences were found in the OF test among experimental groups. Theoffspring of ISO females showed increased NA and 5-HIAA levels, whereas in the offspring persistently housed in isolation condition from weaninguntil adulthood, we detected reduced 5-HT levels and ehnanced 5-HIAA amount. No significant changes in GLU concentrations were detected, while decreased GABA content was observed in the offspring of ISO females exposed to social isolation. Increased ROS levels as well as reduced NF-κB, NOX2 expression were detected in the offspring of ISO females. This was accompanied by reduced redox status and enhanced SOD1 levels. In conclusion, our results suggest that female exposure to chronic social stress before pregnancy might have a profound influence on the offspring neurodevelopment in terms of cognitive, neurochemical and redox-related alterations, identifying this specific time window for possible preventive and therapeutic strategies.
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Affiliation(s)
- Maria Bove
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
| | - Maria Grazia Morgese
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
| | - Stefania Dimonte
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
| | - Vladyslav Sikora
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
| | - Lisa Pia Agosti
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
| | - Maria Adelaide Palmieri
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
| | - Paolo Tucci
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
| | - Stefania Schiavone
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy.
| | - Luigia Trabace
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 20, Foggia 71122, Italy
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Siddi C, Cosentino S, Tamburini E, Concas L, Pisano MB, Ardu R, Deplano M, Follesa P, Maciocco E, Porcu P, Serra M, Pisu MG. Parental Social Isolation during Adolescence Alters Gut Microbiome in Rat Male Offspring. Biomolecules 2024; 14:172. [PMID: 38397408 PMCID: PMC10886888 DOI: 10.3390/biom14020172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/23/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024] Open
Abstract
Previous work from our laboratory demonstrated that parental stress, induced by social isolation starting at puberty, leads to behavioral, endocrine, and biochemical changes in the male, but not female, offspring (ISO-O) of Sprague-Dawley rats. Here, we report alterations in the gut microbiota composition of ISO-O vs. grouped-housed offspring (GH-O), although all animals received the same diet and were housed in the same conditions. Analysis of bacterial communities by next-generation sequencing (NGS) of 16S rRNA gene revealed alterations at family and order levels within the main phyla of Bacteroides, Proteobacteria, and Firmicutes, including an almost total deficit in Limosilactobacillus reuteri (formerly Lactobacillus reuteri) and a significant increase in Ligilactobacillus murinus (formerly Lactobacillus murinus). In addition, we found an increase in the relative abundance of Rhodospirillales and Clostridiales in the families of Lachnospiraceae and Ruminococcaceae, and Bacteroidales in the family of Prevotellaceae. Furthermore, we examined plasma levels of the proinflammatory cytokines interleukin-1-beta and tumor necrosis factor-alpha, which did not differ between the two groups, while corticosterone concentrations were significantly increased in ISO-O rats. Our findings suggest that adverse environmental conditions experienced by parents may have an impact on the likelihood of disease development in the subsequent generations.
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Affiliation(s)
- Carlotta Siddi
- Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (C.S.); (L.C.); (P.F.)
| | - Sofia Cosentino
- Department of Medical Sciences and Public Health, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (S.C.); (M.B.P.); (M.D.)
| | - Elena Tamburini
- Department of Biomedical Sciences, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (E.T.); (R.A.)
| | - Luca Concas
- Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (C.S.); (L.C.); (P.F.)
| | - Maria Barbara Pisano
- Department of Medical Sciences and Public Health, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (S.C.); (M.B.P.); (M.D.)
| | - Riccardo Ardu
- Department of Biomedical Sciences, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (E.T.); (R.A.)
| | - Maura Deplano
- Department of Medical Sciences and Public Health, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (S.C.); (M.B.P.); (M.D.)
| | - Paolo Follesa
- Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (C.S.); (L.C.); (P.F.)
| | - Elisabetta Maciocco
- Neuroscience Institute, National Research Council of Italy (CNR), Monserrato, 09042 Cagliari, Italy; (E.M.); (P.P.); (M.G.P.)
| | - Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Monserrato, 09042 Cagliari, Italy; (E.M.); (P.P.); (M.G.P.)
| | - Mariangela Serra
- Department of Life and Environmental Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Monserrato, 09042 Cagliari, Italy; (C.S.); (L.C.); (P.F.)
| | - Maria Giuseppina Pisu
- Neuroscience Institute, National Research Council of Italy (CNR), Monserrato, 09042 Cagliari, Italy; (E.M.); (P.P.); (M.G.P.)
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Bucknor MC, Gururajan A, Dale RC, Hofer MJ. A comprehensive approach to modeling maternal immune activation in rodents. Front Neurosci 2022; 16:1071976. [PMID: 36590294 PMCID: PMC9800799 DOI: 10.3389/fnins.2022.1071976] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022] Open
Abstract
Prenatal brain development is a highly orchestrated process, making it a very vulnerable window to perturbations. Maternal stress and subsequent inflammation during pregnancy leads to a state referred to as, maternal immune activation (MIA). If persistent, MIA can pose as a significant risk factor for the manifestation of neurodevelopmental disorders (NDDs) such as autism spectrum disorder and schizophrenia. To further elucidate this association between MIA and NDD risk, rodent models have been used extensively across laboratories for many years. However, there are few uniform approaches for rodent MIA models which make not only comparisons between studies difficult, but some established approaches come with limitations that can affect experimental outcomes. Here, we provide researchers with a comprehensive review of common experimental variables and potential limitations that should be considered when designing an MIA study based in a rodent model. Experimental variables discussed include: innate immune stimulation using poly I:C and LPS, environmental gestational stress paradigms, rodent diet composition and sterilization, rodent strain, neonatal handling, and the inclusion of sex-specific MIA offspring analyses. We discuss how some aspects of these variables have potential to make a profound impact on MIA data interpretation and reproducibility.
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Affiliation(s)
- Morgan C. Bucknor
- School of Life and Environmental Sciences, Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
| | - Anand Gururajan
- The Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
| | - Russell C. Dale
- The Children’s Hospital at Westmead, Kids Neuroscience Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia,The Children’s Hospital at Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Markus J. Hofer
- School of Life and Environmental Sciences, Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia,*Correspondence: Markus J. Hofer,
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Exposure to War Prior to Conception: Maternal Emotional Distress Forecasts Sex-Specific Child Behavior Problems. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19073802. [PMID: 35409484 PMCID: PMC8997367 DOI: 10.3390/ijerph19073802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/17/2022] [Accepted: 03/21/2022] [Indexed: 12/04/2022]
Abstract
Objectives: Exposure to maternal stress during the prenatal period adversely affects child outcomes. Recent investigations have shifted to an even earlier period, the preconception period, to better understand the role of this formative period in human health and disease. We investigated the links between maternal emotional distress following preconception exposure to war, and child outcomes at age 10. Material and Methods: Before becoming pregnant, mothers were exposed to missile bombardment on the north of Israel in the 2006 war. Mothers who conceived within 12 months after the war were recruited and compared to mothers who conceived during the same period but lived in Israel but outside missile range. During the initial assessment, mothers completed a questionnaire on emotional distress. At 10 years of age, mothers and children (N = 68) reported on child socio-emotional outcomes. Results: Multiple regression analyses revealed that, in girls, higher maternal emotional distress following preconception war exposure predicted more internalizing and externalizing behavior problems, and more behavior regulation problems. In boys, maternal emotional distress was not significantly related to outcomes. Conclusion: Maternal emotional distress following preconception exposure to war forecasts sex-specific child behavioral problems as reported by the mother and the child. Though the results warrant cautious interpretation because of the relatively small sample size and differential attrition, our findings add to the small but growing body of research on the consequences of maternal stress exposure prior to conception for the next generation.
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Belelli D, Phillips GD, Atack JR, Lambert JJ. Relating neurosteroid modulation of inhibitory neurotransmission to behaviour. J Neuroendocrinol 2022; 34:e13045. [PMID: 34644812 DOI: 10.1111/jne.13045] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/24/2021] [Accepted: 09/15/2021] [Indexed: 12/11/2022]
Abstract
Studies in the 1980s revealed endogenous metabolites of progesterone and deoxycorticosterone to be potent, efficacious, positive allosteric modulators (PAMs) of the GABAA receptor (GABAA R). The discovery that such steroids are locally synthesised in the central nervous system (CNS) promoted the thesis that neural inhibition in the CNS may be "fine-tuned" by these neurosteroids to influence behaviour. In preclinical studies, these neurosteroids exhibited anxiolytic, anticonvulsant, analgesic and sedative properties and, at relatively high doses, induced a state of general anaesthesia, a profile consistent with their interaction with GABAA Rs. However, realising the therapeutic potential of either endogenous neurosteroids or synthetic "neuroactive" steroids has proven challenging. Recent approval by the Food and Drug Administration of the use of allopregnanolone (brexanolone) to treat postpartum depression has rekindled enthusiasm for exploring their potential as new medicines. Although neurosteroids are selective for GABAA Rs, they exhibit little or no selectivity across the many GABAA R subtypes. Nevertheless, a relatively minor population of receptors incorporating the δ-subunit (δ-GABAA Rs) appears to be an important contributor to their behavioural effects. Here, we consider how neurosteroids acting upon GABAA Rs influence neuronal signalling, as well as how such effects may acutely and persistently influence behaviour, and explore the case for developing selective PAMs of δ-GABAA R subtypes for the treatment of psychiatric disorders.
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Affiliation(s)
- Delia Belelli
- Neuroscience, Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Grant D Phillips
- Neuroscience, Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - John R Atack
- Medicines Discovery Institute, Cardiff University, Cardiff, UK
| | - Jeremy J Lambert
- Neuroscience, Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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Almeida FB, Nin MS, Barros HMT. The role of allopregnanolone in depressive-like behaviors: Focus on neurotrophic proteins. Neurobiol Stress 2020; 12:100218. [PMID: 32435667 PMCID: PMC7231971 DOI: 10.1016/j.ynstr.2020.100218] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 03/16/2020] [Accepted: 03/30/2020] [Indexed: 12/18/2022] Open
Abstract
Allopregnanolone (3α,5α-tetrahydroprogesterone; pharmaceutical formulation: brexanolone) is a neurosteroid that has recently been approved for the treatment of postpartum depression, promising to fill part of a long-lasting gap in the effectiveness of pharmacotherapies for depressive disorders. In this review, we explore the experimental research that characterized the antidepressant-like effects of allopregnanolone, with a particular focus on the neurotrophic adaptations induced by this neurosteroid in preclinical studies. We demonstrate that there is a consistent decrease in allopregnanolone levels in limbic brain areas in rodents submitted to stress-induced models of depression, such as social isolation and chronic unpredictable stress. Further, both the drug-induced upregulation of allopregnanolone or its direct administration reduce depressive-like behaviors in models such as the forced swim test. The main drugs of interest that upregulate allopregnanolone levels are selective serotonin reuptake inhibitors (SSRIs), which present the neurosteroidogenic property even in lower, non-SSRI doses. Finally, we explore how these antidepressant-like behaviors are related to neurogenesis, particularly in the hippocampus. The protagonist in this mechanism is likely the brain-derived neurotrophic factor (BFNF), which is decreased in animal models of depression and may be restored by the normalization of allopregnanolone levels. The role of an interaction between GABA and the neurotrophic mechanisms needs to be further investigated.
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Key Words
- 3α,5α-tetrahydroprogesterone
- BDNF
- BDNF, brain-derived neurotrophic factor
- Brexanolone
- CSF, cerebrospinal fluid
- CUS, chronic unpredictable stress
- Depression
- EKR, extracellular signal-regulated kinase
- FST, forced swim test
- GABA, γ-aminobutyric acid
- GABAAR, GABA type A receptor
- HSD, hydroxysteroid dehydrogenase
- NGF, nerve growth factor
- Neurosteroid
- PTSD, post-traumatic stress disorder
- PXR, pregnane xenobiotic receptor
- SBSS, selective brain steroidogenic stimulant
- SSRI, selective serotonin reuptake inhibitor
- Selective brain steroidogenic stimulant
- THP, tetrahydroprogesterone
- TSPO, 18 kDa translocator protein
- TrkB, tropomyosin receptor kinase B
- USV, ultrasonic vocalization
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Affiliation(s)
- Felipe Borges Almeida
- Graduate Program in Health Sciences: Pharmacology and Toxicology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), 90050-170, Porto Alegre, RS, Brazil
| | - Maurício Schüler Nin
- Graduate Program in Health Sciences: Pharmacology and Toxicology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), 90050-170, Porto Alegre, RS, Brazil.,Centro Universitário Metodista do IPA, 90420-060, Porto Alegre, RS, Brazil.,Graduate Program in Biological Sciences: Pharmacology and Therapeutics, Universidade Federal do Rio Grande do Sul (UFRGS), 90040-060, Porto Alegre, RS, Brazil
| | - Helena Maria Tannhauser Barros
- Graduate Program in Health Sciences: Pharmacology and Toxicology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), 90050-170, Porto Alegre, RS, Brazil
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Pisu MG, Boero G, Garau A, Casula C, Cisci S, Biggio F, Concas A, Follesa P, Maciocco E, Porcu P, Serra M. Are preconceptional stressful experiences crucial elements for the aetiology of autism spectrum disorder? Insights from an animal model. Neuropharmacology 2019; 157:107686. [PMID: 31247268 DOI: 10.1016/j.neuropharm.2019.107686] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 06/19/2019] [Accepted: 06/24/2019] [Indexed: 12/26/2022]
Abstract
Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders characterized by changes in social interactions, impaired language and communication, fear responses and presence of repetitive behaviours. Although the genetic bases of ASD are well documented, the recent increase in clinical cases of idiopathic ASD indicates that several environmental risk factors could play a role in ASD aetiology. Among these, maternal exposure to psychosocial stressors during pregnancy has been hypothesized to affect the risk for ASD in offspring. Here, we tested the hypothesis that preconceptional stressful experiences might also represent crucial elements in the aetiology of ASD. We previously showed that social isolation stress during adolescence results in a marked decrease in the brain and plasma concentrations of progesterone and in the quality of maternal care that these female rats later provide to their young. Here we report that male offspring of socially isolated parents showed decreased agonistic behaviour and social transmission of flavour preference, impairment in reversal learning, increased seizure susceptibility, reduced plasma oxytocin levels, and increased plasma and brain levels of BDNF, all features resembling an ASD-like phenotype. These alterations came with no change in spatial learning, aggression, anxiety and testosterone plasma levels, and were sex-dependent. Altogether, the results suggest that preconceptional stressful experiences should be considered as crucial elements for the aetiology of ASD, and indicate that male offspring of socially isolated parents may be a useful animal model to further study the neurobiological bases of ASD, avoiding the adaptations that may occur in other genetic or pharmacologic experimental models of these disorders.
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Affiliation(s)
| | - Giorgia Boero
- Department of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Anna Garau
- Department of Life and Environment Sciences and Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy
| | - Claudia Casula
- Department of Life and Environment Sciences and Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy
| | - Sonia Cisci
- Department of Life and Environment Sciences and Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy
| | - Francesca Biggio
- Department of Life and Environment Sciences and Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy; Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy
| | - Alessandra Concas
- Department of Life and Environment Sciences and Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy; Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy
| | - Paolo Follesa
- Department of Life and Environment Sciences and Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy; Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy
| | - Elisabetta Maciocco
- Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy
| | - Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy
| | - Mariangela Serra
- Department of Life and Environment Sciences and Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy; Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari, Italy
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Biggio F, Talani G, Locci V, Pisu M, Boero G, Ciarlo B, Grayson D, Serra M. Low doses of prenatal ethanol exposure and maternal separation alter HPA axis function and ethanol consumption in adult male rats. Neuropharmacology 2018; 131:271-281. [DOI: 10.1016/j.neuropharm.2017.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 11/26/2017] [Accepted: 12/03/2017] [Indexed: 11/25/2022]
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Combined effect of gestational stress and postpartum stress on maternal care in rats. Physiol Behav 2017; 184:172-178. [PMID: 29179996 DOI: 10.1016/j.physbeh.2017.11.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/20/2017] [Accepted: 11/23/2017] [Indexed: 01/24/2023]
Abstract
Variations in maternal care in the rat influence the development of individual differences in behavioral and endocrine responses to stress. This study aimed to examine the interaction between intragastric intubation during late gestation and postpartum stress, induced by pup separation, on maternal behavior and on dams' emotional state and HPA axis function. Rats received intragastric intubation of water on days 12-20 of gestation or remained untreated in their home cage (naïve dams). Pup separation was used as a model of postpartum stress. The procedure consisted of a daily separation of the dam from its litter for 3h from PND 3 until PND 15. Pup separation was carried out in both naïve and intubated dams. The behavioral results indicate that the association of these two stressors significantly decreased arched-back nursing (ABN) and licking and grooming (LG), behaviors considered important parameters to discriminate the high quality of maternal care. Moreover, dams that received both stressors displayed less nest building and blanket nursing behaviors; no effect on the frequency of passive and total nursing was recorded. The analysis of single effects on ABN and LG, revealed that dams that underwent gestational stress induced by intragastric intubation displayed less LG, but ABN was overall unchanged. On the contrary, pup separation stress significantly increased ABN and LG upon reunion of naïve dams with their pups. Treatments per se or the association of both induced modest changes in plasma levels of allopregnanolone and corticosterone that likely did not influence maternal care. These data show that the association of a mild stress during gestation with an unfavorable experience after parturition had a significant impact on maternal care. This effect seems independent from HPA axis activation or from changes in emotional state; further studies would be necessary to ascertain the neural changes that could contribute to altered maternal behavior in stressed mothers. Moreover, these results suggest that the use of intragastric intubation during gestation would interfere with measures of drug-induced changes in maternal behavior and likely their consequences on the offspring.
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