Infant maltreaatment enhances emocional reactivity to nevelty and induces depressive-like behavior in juvenile rat

AILEN, COLAPIETRO; JAZMÍN, GRILLO; MARIANELA, CEOL RETAMAL; MERCEDES, OLIVERA; ANDREA, PECILE; MARTA, ANTONELLI; MARIA E, PALLARÉS

Belém

Congreso; 3rd FALAN CONGRESS; 2022

Falan

Infant maltreatment is a public health problem with long-term consequences on the individual’s physical and mental health. In Argentina, 7 out of 10 infants between the ages of 2 to 4 are subjected to violent methods of discipline, which include physical and psychological aggression. Infant maltreatment predisposes individuals to develop emotional disorders, including depression and anxiety, which might be mediated by dysregulation of the stress system response. Although the current evidence on this problem focuses mainly on adults, to date, little studies have examined the effects of infant maltreatment on younger individuals, and its relevance for the early onset of stress-related disorders. In here, we assessed the impact of infant maltreatment on rat offspring stress system immediately after finishing the maltreatment protocol, and on the emergence of anxiety-/depressive-like behaviors at juvenile age. We used an animal model of early life maltreatment known as the “scarcity-adversity model” (SAM) in where the mother is given insufficient bedding for nest building during postpartum day (PND) 8 to 12. During SAM protocol we tested patterns of maternal behavior towards her pups. After finishing SAM exposure at PND 13, we analyze offspring body weight and adrenal glands weight. We further measured pups’ corticosterone levels in serum. From PND 24 to 28, offspring were exposed to a behavioral test battery to evaluate stress-related behaviors. Mothers exposed to SAM had enhanced fragmented and violent behavior towards their offspring than Control dams (regular bedding conditions). In PND 13 pups, SAM did not affect their body weight gain. However, both female and male SAM offspring had increased corticosterone levels in serum than control pups. At juvenile age SAM offspring of both sexes spent more time and did a greater amount of rearing without wall (unsupported) in the Open field test, a behavior that has been associated with greater emotionality. In the Forced swimming test, both SAM males and females presented greater depressive-like behaviors compared to controls, spending less time swimming and climbing and more time immobile. In conclusion, infant maltreatment generates stress in the offspring due to the increase in corticosterone levels and this modifies their coping strategies when faced with a novel environment or an environment with no escape such as Open-field test and Forced swimming test at juvenile age. These results provide us with more information about emerging behaviors at an early age as a consequence of infant maltreatment, which may be useful for the development of anticipated interventions that prevent the establishment of psychopathologies later in life.