Mother-infant separation leads to hypoactive behavior in adolescent Holtzman rats.
This is the first study of the effects of mother-infant separation (MS) on adolescent behavior of Holtzman (HO) rats. Different rat strains, such as Harlan Sprague-Dawley and HO, share a common origin. However, MS may lead to hypoactive behavioral effects in HO rats because of their greater susceptibility to show depressive-like responses to stress. Sixty HO pups were divided into three groups at postnatal day 2 (P2). For 10 days, the MS group was separated 6h 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 HO rats for predominantly hypoactive/anxiety-like behaviors when exposed to an early life stressor.
Spivey
Jaclyn
J
Department of Psychology and Institute for Neuroscience, University of Texas at Austin, Austin, TX 78712-0187, USA.
Barrett
Douglas
D
Padilla
Eimeira
E
Gonzalez-Lima
F
F
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000523:psychology; D001522:Behavior, Animal / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D005260:Female; D006234:Handling, Psychological; D008297:Male; D008425:Maternal Behavior / Q000502:physiology*; D008426:Maternal Deprivation; D009043:Motor Activity / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013028:Space Perception / Q000502:physiology; D013315:Stress, Psychological / Q000523:psychology