Cardiorespiratory regulation and activity patterns of rat pups studied with their mothers during the nursing cycle

Abstract

Hofer, Myron A., and Grabie, Morris (1971) . Cardiorespiratory Regulation and Activity Patterns of Rat Pups Studied with their Mothers during the NursingCycle. DEVELOPMENTAL PSYCHOBIOLOGY, 4(2): 169-1 80. Rat pups aged 10 to 19 days were implanted with chronic electrodes and recorded while freely moving in the litter situation, during nursing and throughout naturally occurring maternal absences. Heart rates were significantly higher in the mother's presence (p<.Ol) while respiratory rates and percent of time spent active were identical under the 2 conditions. Pups' inactive heart rates progressively increased during the 20 min of nursing, while no such time trends were evident in other measures. Inactive heart rates decreased significantly (p<.OI) as a function of age; respiratory rates and activity during nursing showed similar trends. A histogram of number of periods of activity bursts of different durations while pups were nursing showed a preponderance of 1-to 5-sec bursts which were observed to be associated with active sucking and pawing movements. This pattern of short bursts of spontaneous activity was repeated almost identically when the mother was absent, although the behavior was qualitativeky differtnt. In a second experiment, increases in pups' body temperature of .2 C to 1 .O C were found to accompany active nursing. If such increases were imposed by an artificial heat source, heart rates of pups actually fell slightly. In a third study, heart rates were recorded from nursing mothers and found to be relatively unaffected by stimulation from the pups. preweaningbehavior respiration nursing maternal behavior temperature separation early experience activity laboratory rat heart rate

Studies on How Early Maternal Separation Produces Behavioral Change in Young Rats

“…The behavior was very similar in quality and intensity to that observed in a litter of pups with their mother. The periodicity of these bursts of active scrambling while the litter is with the mother have been observed and recorded in a previous publication (13). The great majority were of short duration (1-5 sec), while intervening inactive periods were most frequently 1-5 sec also, but ranged in duration up to 1 min or more in some cases.…”

Physical stimulation reduces the body temperature of infant rats

“…Following recording of prestimulation rectal temperatures, pups were placed in a 32°C incubator with either a 1) normal humidity incubator (75%-78% relative humidity) or 2) high-humidity incubator (98%-100% relative humidity) for a 10-min habituation period, followed by a 5-min treatment procedure. During the 5-min treatment period pups were either: 1) stroked every 1 min for 15 sec, a schedule of stimulation which more closely approximates that which pups recceived from the dam (Barnett & Walker, 1974;Grota & Ader, 1969;Hofer, 1975Hofer, ,1983Hofer & Garbie, 1971;Moore & Powers, 1986), or 2) received no stimulation.…”

Sleep-Wake State Organization in Infant Rats with Episodic Respiratory Disturbance Following Sinoaortic Denervation

“…Subcutaneous electrodes were placed across the anterior and posterior lateral thorax for recording respiratory pattern by impedance pneumography. This method is fully described in previous publications (4,5). The pups were replaced with their mothers for 2 days prior to the experiment to allow adaptation to the electrodes.…”