Early handling, but not maternal separation, decreases emotional responses in two paradigms of fear without changes in mesolimbic dopamine

Madruga, Clarice S.; Xavier, Léder Leal; Achaval, Matilde; Sanvitto, Gilberto Luiz; Lucion, Aldo Bolten

doi:10.1016/j.bbr.2005.08.005

Cited by 63 publications

(53 citation statements)

References 31 publications

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“…Early handling made the rats in this group less fearful, less stressed, and more risk-takers in the light-dark test, as evidenced by more ambulatory behavior in the light area of this arena. This finding corroborates other published studies in which a 15-minute separation period results in attenuated anxiety-like behavior and increased risk-taking in an open-field (Cannizzaro et al, 2006, Madruga et al, 2006 as well as reductions in conditioned fear responding (Meerlo et al, 1999). MS had the exact opposite effect, as seen in the light-dark test on P29, which differentiated between the three groups more than any other behavior measure in any other session of this study (P28, P29, P30).…”

Section: Discussionsupporting

confidence: 81%

Mother–infant separation leads to hypoactive behavior in adolescent Holtzman rats

Spivey

Barrett

Padilla

et al. 2008

Behavioural Processes

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This is the first study of the effects of mother-infant separation (MS) on adolescent behavior of Holtzman rats. Different rat strains, such as Harlan Sprague-Dawley and Holtzman, share a common origin. However, MS may lead to hypoactive behavioral effects in Holtzman rats because of their greater susceptibility to show depressive-like responses to stress. Sixty Holtzman pups were divided into 3 groups at postnatal day 2 (P2). For 10 days, the MS group was separated 6 hours daily and the early handled (EH) group 15 min daily. A standard facility reared (SFR) group was not separated. Animals were tested for novel open-field activity (P28), defensive withdrawal in a light-dark (LD) apparatus (P29) and familiar open-field (P30). Behavioral measures were classified into general activity (ambulatory and short movement time), orienting (rearing time) and risk-taking (velocity and exposed zone time). MS rats displayed reductions in general activity and risk-taking, and increases in orienting time. In contrast, EH favored risk-taking behavior, which may be consistent with previous findings implicating early handling as beneficial in coping with stress. Sex differences in these behaviors were limited. This study suggests a genetic predisposition in Holtzman rats for predominantly hypoactive/anxiety-like behaviors when exposed to an early life stressor.

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Section: Discussionsupporting

confidence: 81%

Mother–infant separation leads to hypoactive behavior in adolescent Holtzman rats

Spivey

Barrett

Padilla

et al. 2008

Behavioural Processes

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“…Additionally, as adults, the animals exhibited less fear-like behavior than those that were not subjected to maternal separation and tactile stimulation. These results are consistent with previous reports, in which animals handled during the neonatal period exhibited less fear-like behavior when exposed to the open field test (Madruga et al, 2006;Padoin et al, 2001).…”

Section: Discussionsupporting

confidence: 93%

Interventions in the neonatal environment in rats and their relationship to behavior in adulthood and maternal behavior.

Azevedo¹,

Souza²,

Donadio³

et al. 2010

Psychology & Neuroscience

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The objective of this study was to assess the role of environmental/nest components and maternal behavior after several neonatal interventions on subsequent behavioral responses. Male Wistar rats were subjected to different neonatal interventions and were later evaluated for innate fear-like behavior in adulthood. The experimental groups included nonhandled (i.e., animals were not touched), handled (i.e., animals were separated from their mother, removed from the nest, and handled for 10 min/day), brief maternal separation (i.e., the mother was removed from the homecage for 10 min/day, and the pups remained in their cages without being touched), and tactile stimulation (i.e., the mother was removed from the homecage, and pups were stimulated with a brush for 10 min/day within the nest). The mother's behavior was recorded during the neonatal period, and the male pups were later tested in the open field as adults. The results revealed that only mothers whose pups were handled had an increase in the duration of licking behavior compared with the other groups. In the open field test, we observed decreased behavioral innate fear-like responses in male adults in the handled and brief separation groups compared with the others groups. Our results confirm that interventions during the neonatal period cause stable behavioral changes (decreased innate fear) in adulthood and that absent or excessive tactile stimulation appears to be an important factor. Both repeated disruption of the mother-infant relationship and withdrawal from the environment/nest are factors that exert profound effects on the development of the animals.

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“…Arnold and Siviy (2002) reported hyperactive behavior in a maternal separation group of experimental animals, but not in a deprivation group. However, other investigators reported increased activity in adult rats after 3 min/day of maternal deprivation for 10 days during the first 2 weeks of life (Madruga et al, 2006). Also, different results were obtained regarding fearfulness after different maternal deprivation/separation paradigms (Macri et al, 2004;Madruga et al, 2006).…”

Section: Introductionmentioning

confidence: 57%

“…However, other investigators reported increased activity in adult rats after 3 min/day of maternal deprivation for 10 days during the first 2 weeks of life (Madruga et al, 2006). Also, different results were obtained regarding fearfulness after different maternal deprivation/separation paradigms (Macri et al, 2004;Madruga et al, 2006). Previously, Lee et al (2001) introduced a new animal model of early-life stress, the maternal social separation (MSS) paradigm, i.e., separation of newborn pups from their dam and littermates after postnatal day (PND) 14.…”

Section: Introductionmentioning

confidence: 95%

Maternal Social Separation of Adolescent Rats Induces Hyperactivity and Anxiolytic Behavior

Kwak

Lee

Kwon

et al. 2009

Korean J Physiol Pharmacol

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Early handling, but not maternal separation, decreases emotional responses in two paradigms of fear without changes in mesolimbic dopamine

Cited by 63 publications

References 31 publications

Mother–infant separation leads to hypoactive behavior in adolescent Holtzman rats

Mother–infant separation leads to hypoactive behavior in adolescent Holtzman rats

Interventions in the neonatal environment in rats and their relationship to behavior in adulthood and maternal behavior.

Maternal Social Separation of Adolescent Rats Induces Hyperactivity and Anxiolytic Behavior

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