Evaluation of the neurochemical and behavioral effects of enviromenmtal enrichment in animal submitted to maternal privacy.

Name: Randriely Merscher Sobreira de Lima
Type: MSc dissertation
Publication date: 14/07/2017

Namesort descending Role
Ana Paula Santana de Vasconcellos Bittencourt Advisor *

Examining board:

Namesort descending Role
Ana Paula Santana de Vasconcellos Bittencourt Advisor *
Athelson Stefanon Bittencourt Co advisor *
Jeyce Willig Quintino dos Santos External Examiner *
Valquíria Camin de Bortoli Internal Alternate *
Vanessa Beijamini Harres Internal Examiner *

Summary: The relationship between mother and its pups is extremely important for
mammals, given the importance of maternal care and attachment in the first days of life. Traumatic events during this period may impair physiological and
psychological development, potentially causing short- and long-term changes.
Maternal deprivation (MD) is a well-established protocol used to investigate both neurobiological and behavioral changes such as anxiety disorders. It has been demonstrated that environmental enrichment (EE) protocols promote numerous sensory, motor, and cognitive benefits in laboratory animals, and may be used to intervene in changes caused by postnatal adverse events and to prevent the occurrence of psychiatric disorders in adulthood. In this context, we evaluated the implications of EE as a strategy to prevent the maternal deprivation effects on anxiety behaviors and gene expression of the serotonergic system components. Male Wistar rats were deprived of maternal presence during two 24-hour periods on 11th and 13th postnatal days (PND). Non-deprived animals were kept under minimal manipulation conditions. In 21th PND, after weaning, the animals were submitted to EE or standard housing conditions, and there remained until early adulthood. In 60th PND, we initiated the behavioral anxiety tests: T-maze test, open field (OF), predator odor test (POT); and inhibitory avoidance test. After that, the animals were euthanized to obtain the amygdala and dorsal raphe nucleus. mRNA expression of the serotonergic system components (5-HT1AR, 5-HT2AR, 5-HT2CR, SERT and TPH2) were evaluated in both structures. We observed in the T-maze that the MD increased the avoidance time 1, while the enrichment increased the avoidance time 2, without changes in escape latencies. MD did not cause changes in OF, but EE decreased the locomotor activity in all evaluated parameters. MD also did not altered behavior in the POT, but EE decreased the time in the hidden compartment and increased the investigation of the odor source. None of the treatments caused changes in the inhibitory avoidance test. Neither MD nor EE caused changes in mRNA expression of serotonergic system components in the amygdala and dorsal raphe nucleus. We can conclude that both treatments induce anxiogenic effects without altering aversive memory, but just EE alters the response to new environments and contexts. Despite the well established involvement of dorsal raphe and amygdale with anxiety, the serotonergic neurotransmission in these structures is not altered by maternal deprivation or environmental enrichment.

Keywords: Maternal deprivation. Anxiety. Environmental enrichment. Serotonergic system.

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