Behavior of mother rats in conflict tests sensitive to antianxiety agents.

Abstract

Previous studies of freezing and open-field activity have demonstrated that lactating rats are less fearful or less anxious than nonpregnant ones. The purpose of this investigation was to observe the behavior of mother rats in conflict tests, which are frequently used in studies on the neurobiology of anxiety. In the punished drinking test, in which licking from a water spout is punished by electric shocks, mothers (observed on Day 1 postpartum following 24 hr of water deprivation) were found to drink more than virgins. Mothers (Day 1 postpartum) also consumed more food than controls in an unfamiliar open field. In contrast, no difference between mothers (Day 5 postpartum) and virgins was present in the exploration of an electrified shock probe. The largest maternal anticonflict effects in the drinking and feeding tests were recorded when the females were tested with their pups. Increased punished drinking was also observed in virgin rats treated with the anxiolytic benzodiazepine midazolam. Water-deprived virgins and mothers did not differ in the shock titration test, a result suggesting that diminished pain reactivity was unlikely to account for the increased punished drinking in mothers. Moreover, females in late pregnancy, which are hypoalgesic (Gintzler, 1980), did not lick more than virgins in the punished drinking test. Following 24 hr of water deprivation, unpunished drinking was higher in lactating females than in virgins, so the increased acceptance of punishment by mothers might have been due to their being more thirsty than virgins.(ABSTRACT TRUNCATED AT 250 WORDS)

A Postpartum Model in Rat: Behavioral and Gene Expression Changes Induced by Ovarian Steroid Deprivation

“…Previous studies are in agreement with this finding, reporting that in rodents the dam shows an enhanced aggressive behavior toward an intruder after parturition (40)(41)(42)(43), although reduced anxiety has been reported (40,44). There is clinical evidence that the symptoms of PPD may include anxiety accompanied by aggression, sometimes resulting in obsessions of child harm (5).…”

Influence of lactation on motor activity and elevated plus maze behavior

“…Motherhood in rodents induces a reduced reactivity to normally aversive stimuli (6)(7)(8). Lactating rats are less inclined to run away from an intruder (6) and have lower reactivity in classical conflict tests (8). In a light/dark choice situation, lactating mice displayed less avoidance of the aversive illuminated environment than did virgin animals (5).…”

“…These changes ultimately reflect the biologically useful appearance of some behaviors and modulation of others such as taking care of the pups and aggression, respectively (4,5). Motherhood in rodents induces a reduced reactivity to normally aversive stimuli (6)(7)(8). Lactating rats are less inclined to run away from an intruder (6) and have lower reactivity in classical conflict tests (8).…”

Open field behavior and intra-nucleus accumbens dopamine release in vivo in virgin and lactating rats.

“…Motherhood in rodents induces reduced reactivity to normally aversive stimuli (Fleming & Luebke, 1981;Ferreira, Hansens, Nielsen, Archer, & Minor, 1989). Lactating rats are less inclined to run away from an intruder (Fleming & Luebke, 1981) and exhibit lower reactivity in classic conflict tests (Ferreira et al, 1989). In a light/dark choice situation, lactating mice displayed less avoidance of the aversive illuminated environment than virgin animals (Maestripieri & D'Amato, 1991).…”

“…Much data from the literature suggest that lactating rats exhibit less fear in response to several stimuli (Hard & Hansen, 1985; Pereira, Uriarte, Agrati, Zuluaga, & Ferreira, 2005), including in the open field task (Ferreira, Hansen, Nielsen, Archer & Minor, 1989), compared with other stages of the female reproductive cycle. This reduction in general fearfulness observed postpartum appears to be related to the caring of offspring.…”