Postsuckling behavioral arousal in weanling rats (Rattus norvegicus).

Abstract

Twenty-day-old litters and their dams were observed in seminatural habitats consisting of a nest compartment and adjacent open field that contained powdered rat chow. It was found that pups displayed marked bursts of activity after suckling. Independent feeding reliably followed nursing bout termination (Experiment 1). Nipple withdrawal, with or without milk transfer, induced behavioral arousal whereas withdrawal of thermotactile and conspecific odor cues did not (Experiments 2-3). Increased thermogenesis was observed following milk transfer (Experiment 4). Finally, preweanling pups (10- to 12-day-olds) also displayed postsuckling arousal within the confines of the nest; full locomotor expression of this arousal was not evident until weaning age (Experiment 5). It was concluded that postsuckling arousal in weanlings functions to stimulate activities performed away from the nest and suckling, propelling pups into the field where feeding begins.

Short-term influence of breastfeeding on the infants' interaction with the environment

“…Recent research demonstrated that at the time of weaning, specific components of the nursing bout have immediate effects on exploratory and grooming behaviors in the young animal. That is, withdrawal of the nipple and milk transfer leads to pups engaging in more locomotor activity, playing with other conspecifics, and self-grooming (Gerrish & Alberts, 1997). It is important to note that, in the present study, the infants did not exhibit increased activity following breastfeeding, a finding which is consistent with those of Paul and colleagues (1996).…”

“…The events associated with early feeding interactions can shape behavior in predictable and meaningful ways (Blass, 1994;Gerrish & Alberts, 1997;Oberlander et al, 1992). In the context of the motherinfant breastfeeding dyad, we identified a short-term, stimulating effect of breastfeeding on the 4-to 6-month-old infants' interaction with stimuli in their environment.…”

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ABSTRACT: The present study tested Keywords: breastfeeding; infant; activity; actigraph; visual attentiveness; behavior Weanling-aged rat pups displayed marked bursts of locomotor activity and heightened interactions with their surrounds immediately following the termination of a suckling bout (Gerrish & Alberts, 1997). Specific components of the nursing bout contributed to this behavioral change.

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Emergence of the exploratory motive in rats

“…This affinity is adaptive to these altricial infants, who must depend on the mother for nutrition, thermoregulation, grooming, and protection from predators; however, the attraction to the home nest must be overcome if infant rats are to begin to forage for solid food and ultimately become self-sufficient adults (Alberts & Leimbach, 1980). Though hunger is a potential motivator for these early forays from the nest, other motivators may influence this behavior such as a drive to explore novel places (Gerrish & Alberts, 1997). This motive has been well documented in adult rats, most commonly through two behavioral tests: novelty induced locomotion and novelty preference (Kelly, 1993) Novelty-induced locomotion is thought to be a type of exploratory behavior evoked by exposure to a novel context.…”

Mercaptoacetate decreases latency to initiate independent ingestion, but not suckling, in preweanling rats

“…Previous work examining cues related to the transition from suckling to independent ingestion have suggested that signals related to changes in milk supply by the dam are not involved in the initiation of independent ingestion; pups showed similar patterns of initiation of independent ingestion whether in the presence of a lactating dam, a dam providing suckling opportunities but no milk, or a dam providing neither suckling opportunities nor milk (Thiels & Alberts, 1991). In addition, pups appear to initiate intake just after completing bouts of suckling, suggesting that deficit signals like those related to changes in fat or glucose utilization are not critical to the normal initiation of independent ingestion (Gerrish & Alberts, 1997). However, as demonstrated in the present experiments, signals related to changes in the utilization of fats do appear to preferentially modulate independent ingestion by at least 15 days of age, and previous work has demonstrated that just several days later, 2-DG reduces latency to ingest in the context of independent ingestion (Gisel & Henning, 1980).…”