Growth, Neurobehavioral and Circadian Rhythm Development in Newborn Baboons

Abstract

We measured body temperature continuously using telemetry to determine the development of circadian rhythmicity in neonatal baboons after birth. Twelve fetal baboons (nine males and three females) of known gestational age ranging from 167 to 193 d were studied. We eliminated the influence of maternal factors by hand rearing these infants from the moment of birth until 45 d of life. All infants showed steady growth in body weight, head circumference, and crown-rump length. Neurobehavioral responses including visual and auditory orientation, motor maturity, irritability, and consolability increased as a function of age. Circadian rhythms of body temperature were present in the second week of life, and the amplitude of this rhythm increased throughout the developmental period studied. The increase in the amplitude of circadian body temperature rhythm independent of environmental time cues may indicate the maturation of the brain. These neonatal nonhuman primates offer an excellent model for studying neurobehavioral development and maturation of circadian rhythms while controlling external factors in a manner that is not possible with human neonates. Circadian rhythms with a periodicity of approximately 24 h are endogenous rhythms that regulate many physiologic functions. These rhythms are generated by a biologic clock located in the suprachiasmatic nucleus in the brain (1). Appropriate appearance of perinatal circadian rhythms, both fetal and neonatal, is a fundamental expression of normal brain maturation (2). The extent to which these rhythms are present at birth and/or mature during the early neonatal period has been studied extensively in rodents (3). However, there are very few relevant studies on maturation in primates, either human or nonhuman (4, 5). The few recent nonhuman primate neonatal studies that exist relate only to the responsiveness of these rhythms to light (6, 7).Maternal endocrine and other rhythms, however, have been investigated in nonhuman primates. Some have been shown to be truly circadian, e.g. body temperature and uterine myometrial activity (8, 9). Maternal hormonal rhythms have also been shown to persist in the absence of external cues, the ultimate criterion for a circadian rhythm (10). In addition, several other studies have demonstrated 24-h maternal rhythms in human and nonhuman primates (11, 12) during the last trimester of gestation. These maternal rhythms, too, may yet prove to be truly circadian; however, they have not yet been shown to free run in the absence of external cues.The purpose of the present study was to determine whether neonatal baboons express a clear circadian rhythm in body temperature in the absence of postnatal environmental time cues including those received from their mothers. In addition, we wished to evaluate any increase in the amplitude of the rhythm as a function of postnatal age. Growth and neurobehavioral development were evaluated at weekly intervals. METHODSTwelve pregnant baboons (Papio papio) of known gestational age (term is approximately 180 d ...

Inexpensive Home Infrared Living/Environment Sensor with Regional Thermal Information for Infant Physical and Psychological Development

“…BT, a physiological index, showed consistent circadian patterns in early age stages but varied in the late stage ( Figure 2 E). This finding confirms results from previous reports that diurnal body temperature rhythms emerge earlier than behavioral rhythms in primates and rodents [ 19 , 50 , 51 ] and are affected by behavioral [ 52 ] and thermal conditions [ 53 ]. BD was generally less phasic but BD (0.99) was more phasic ( Figure 2 D).…”

“…One such tool for the assessment of neurodevelopment is a non-invasive, longitudinal method to evaluate an individual’s interaction with their social and physical environment through the monitoring of location and motion and associated circadian rhythms while in the home environment. Such assessments are of particular value given the relationship between early neurodevelopment and the development of circadian rhythms [ 17 , 18 , 19 , 20 ] with lifelong and potentially generational mental health [ 21 , 22 , 23 ] perhaps through epigenetic programming during the highly sensitive infant period [ 24 , 25 , 26 ].…”

Emergence of physiological rhythmicity in term and preterm neonates in a neonatal intensive care unit

“…Emergence of circadian rhythmicity has been reported to be associated with brain maturation of preterm infants [ 33 , 34 ]. In term neonates, circadian cycles are detected immediately after birth and subsequently disappear and are not detectable until 3 to 4 weeks of postnatal life [ 22 ].…”

Baboon Nursery Rearing Practices and Comparisons between Nursery-Reared and Mother-Reared Individuals

“…The timing and reason for entry into the nursery may have affected weight parameters (Levin and Carey, 1988). Although detailed information on the development of neurobehavioral and circadian rhythm is available for nursery-reared baboons (Mirmiran et al, 2001), comparable information for mother-reared individuals is lacking.…”