Short-term but not long-term exposure to an enriched environment reduces unconditioned fear responses but not conditioned fear responses

Environmental enrichment (EE) has been shown to produce beneficial effects in animal models of a wide variety of neurological and psychiatric disorders. EE exhibits antidepressant function; reduces anxiety, improves spatial learning and memory impairment. EE can reduce sensitivity to loss of reward by reducing frustration-like emotional states and facilitates the extinction of conditioned fear. However, some studies related to the emotional effects of EE present controversial results such as reduction or increase in anxiety. The time of exposure to an enriched environment seems to be an important factor in the behavioral responses presented by animals subjected to aversive stimuli. The present study compared the effects of two and four week exposure to EE with young adult Wistar rats under the same conditions and protocol on fear behavioral parameters in the face of footshock (unconditioned fear) and on re-exposure to an environment after electrical shock pairing (conditioned fear). We showed that the EE with a duration of two weeks reduced the freezing response of the animals in an unconditioned fear situation, that is, with the aversive stimulus present in the environment, however, did not influence the same behavior in a conditioned fear situation. In addition, the short-term EE developed the locomotor and exploratory activity, identified by the high rearing behavior, which may also suggest a low level of anxiety in these animals. We can conclude that EE changes the unconditioned fear responses of young adult rats. In addition, the duration of EE interferes differently, being two weeks of treatment with EE sufficient to cause improvement in coping with unconditioned aversive situations. We suggest that the emotional benefits resulting from the welfare provided by EE can be abolished by the longer duration of this treatment, due to the already known effect of tolerance to lasting or abundant rewards.

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Short-Term Exposure to Enriched Environment in Adult Rats Restores MK-801-Induced Cognitive Deficits and GABAergic Interneuron Immunoreactivity Loss

Molecular Neurobiology ◽

10.1007/s12035-017-0715-z ◽

2017 ◽

Vol 55 (1) ◽

pp. 26-41 ◽

Cited By ~ 9

Author(s):

Ane Murueta-Goyena ◽

Naiara Ortuzar ◽

Pascual Ángel Gargiulo ◽

José Vicente Lafuente ◽

Harkaitz Bengoetxea

Keyword(s):

Cognitive Deficits ◽

Enriched Environment ◽

Gabaergic Interneuron ◽

Short Term ◽

Adult Rats ◽

Mk 801 ◽

Short Term Exposure

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Effects of sleep deprivation on spatial learning and memory in juvenile and young adult rats.

Psychology & Neuroscience ◽

10.1037/pne0000075 ◽

2017 ◽

Vol 10 (1) ◽

pp. 109-116 ◽

Cited By ~ 2

Author(s):

Christopher P. Ward ◽

Jessica I. Wooden ◽

Ryan Kieltyka

Keyword(s):

Young Adult ◽

Sleep Deprivation ◽

Learning And Memory ◽

Spatial Learning ◽

Spatial Learning And Memory ◽

Adult Rats

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Early postnatal environmental enrichment restores neurochemical and functional plasticities of the cerebral cortex and improves learning performance in hidden-prenatally-malnourished young-adult rats

Behavioural Brain Research ◽

10.1016/j.bbr.2019.02.001 ◽

2019 ◽

Vol 363 ◽

pp. 182-190 ◽

Cited By ~ 2

Author(s):

Héctor Burgos ◽

Alejandro Hernández ◽

Luis Constandil ◽

Miguel Ríos ◽

Osvaldo Flores ◽

...

Keyword(s):

Cerebral Cortex ◽

Young Adult ◽

Environmental Enrichment ◽

Learning Performance ◽

Adult Rats

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Developmental lead exposure impairs extinction of conditioned fear in young adult rats

NeuroToxicology ◽

10.1016/j.neuro.2008.06.010 ◽

2008 ◽

Vol 29 (6) ◽

pp. 1127-1130 ◽

Cited By ~ 9

Author(s):

Jennifer L. McGlothan ◽

Marzena Karcz-Kubicha ◽

Tomás R. Guilarte

Keyword(s):

Young Adult ◽

Lead Exposure ◽

Conditioned Fear ◽

Adult Rats

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Stroking stimulation of the skin elicits 50-kHz ultrasonic vocalizations in young adult rats

The Journal of Physiological Sciences ◽

10.1186/s12576-020-00770-1 ◽

2020 ◽

Vol 70 (1) ◽

Author(s):

Rie Shimoju ◽

Hideshi Shibata ◽

Miyo Hori ◽

Mieko Kurosawa

Keyword(s):

Young Adult ◽

Positive Emotion ◽

External Genitalia ◽

The Body ◽

Ultrasonic Vocalizations ◽

Emotional States ◽

Ventral Region ◽

Head Region ◽

Adult Rats ◽

Stimulation Of

Abstract The present study aimed to clarify if stroking stimulation of the skin produces positive emotion in rats. 50-kHz ultrasonic vocalizations (USVs) were recorded as an index of the positive emotion. Stroking stimulation was applied to the ventral, dorsal, or head region of the body while the rat was in a vertical holding condition. Rats emit abundant 50-kHz USVs in response to stroking, and the number of the USVs was not different among these three stimulated regions. Other stimulations, such as light touching of the abdominal area, swinging of the body back and forth, or stroking of the external genitalia under vertical holding condition, produced significantly less 50-kHz USVs. Furthermore, different call subtypes were observed during and after stroking of the ventral region. In particular, “Trill” calls, a representative index of positive emotion, were dominant after stimulation. These results suggest that stroking of the skin induces positive emotional states.

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Environmental enrichment reverses the detrimental action of early inconsistent stimulation and increases the beneficial effects of postnatal handling on shuttlebox learning in adult rats

Behavioural Brain Research ◽

10.1016/0166-4328(94)90157-0 ◽

1994 ◽

Vol 61 (2) ◽

pp. 169-173 ◽

Cited By ~ 60

Author(s):

Rosa M. Escorihuela ◽

Adolf Tobeña ◽

Albert Fernández-Teruel

Keyword(s):

Environmental Enrichment ◽

Adult Rats ◽

Beneficial Effects ◽

Postnatal Handling

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Sedentary Life and Reduced Mastication Impair Spatial Learning and Memory and Differentially Affect Dentate Gyrus Astrocyte Subtypes in the Aged Mice

Frontiers in Neuroscience ◽

10.3389/fnins.2021.632216 ◽

2021 ◽

Vol 15 ◽

Author(s):

Fabíola de Carvalho Chaves de Siqueira Mendes ◽

Luisa Taynah Vasconcelos Barbosa Paixão ◽

Daniel Guerreiro Diniz ◽

Daniel Clive Anthony ◽

Dora Brites ◽

...

Keyword(s):

Dentate Gyrus ◽

Learning And Memory ◽

Spatial Learning ◽

Environmental Enrichment ◽

Enriched Environment ◽

Spatial Learning And Memory ◽

Aged Mice ◽

Impoverished Environment ◽

Age Related ◽

The Impact

To explore the impact of reduced mastication and a sedentary lifestyle on spatial learning and memory in the aged mice, as well as on the morphology of astrocytes in the molecular layer of dentate gyrus (MolDG), different masticatory regimens were imposed. Control mice received a pellet-type hard diet, while the reduced masticatory activity group received a pellet diet followed by a powdered diet, and the masticatory rehabilitation group received a pellet diet, followed by powder diet and then a pellet again. To mimic sedentary or active lifestyles, mice were housed in an impoverished environment of standard cages or in an enriched environment. The Morris Water Maze (MWM) test showed that masticatory-deprived group, regardless of environment, was not able to learn and remember the hidden platform location, but masticatory rehabilitation combined with enriched environment recovered such disabilities. Microscopic three-dimensional reconstructions of 1,800 glial fibrillary acidic protein (GFAP)-immunolabeled astrocytes from the external third of the MolDG were generated using a stereological systematic and random sampling approach. Hierarchical cluster analysis allowed the characterization into two main groups of astrocytes with greater and lower morphological complexities, respectively, AST1 and AST2. When compared to compared to the hard diet group subjected to impoverished environment, deprived animals maintained in the same environment for 6 months showed remarkable shrinkage of astrocyte branches. However, the long-term environmental enrichment (18-month-old) applied to the deprived group reversed the shrinkage effect, with significant increase in the morphological complexity of AST1 and AST2, when in an impoverished or enriched environment. During housing under enriched environment, complexity of branches of AST1 and AST2 was reduced by the powder diet (pellet followed by powder regimes) in young but not in old mice, where it was reversed by pellet diet (pellet followed by powder and pellet regime again). The same was not true for mice housed under impoverished environment. Interestingly, we were unable to find any correlation between MWM data and astrocyte morphological changes. Our findings indicate that both young and aged mice subjected to environmental enrichment, and under normal or rehabilitated masticatory activity, preserve spatial learning and memory. Nonetheless, data suggest that an impoverished environment and reduced mastication synergize to aggravate age-related cognitive decline; however, the association with morphological diversity of AST1 and AST2 at the MolDG requires further investigation.

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