Multi-group multi-time point confirmatory factor analysis of the triadic structure of temperament: A nonhuman primate model.

Attempts to describe the latent structure of human infant temperament have led some to suggest the existence of three major dimensions. An earlier exploratory factor analysis (EFA) supported a triadic structure of temperament in week-old rhesus monkey infants, paralleling the structure in human infants. This study sought to confirm the latent triadic structure of temperament across the first month of life in a larger sample of rhesus monkey infants (N = 668), reared by their mothers or in a neonatal nursery.

Neonatal temperament and neuromotor differences are predictive of adolescent alcohol intake in rhesus monkeys (Macaca mulatta).

Identifying predictors of teenage alcohol use disorder (AUDs) is a major health initiative, with studies suggesting that there are distinct personality-related traits that underlie patterns of alcohol intake. As temperament is biologically based, identifiable early in life, and stable across time, it is considered the foundation of personality. As such, we hypothesized that neonatal temperament traits would predict anxiety-mediated adolescent alcohol consumption.

Environmental control, social context, and individual differences in behavioral and cortisol responses to novelty in infant rhesus monkeys.

The effects of appetitive controllability on behavioral and cortisol reactivity to novelty in 12 infant rhesus monkeys were studied. Surrogate-peer-reared infants had homecage access to food treats contingently via lever pressing ("master") or noncontingently ("yoked") for 12 weeks from postnatal month 2. Masters lever-pressed more, but did not differ in baseline cortisol.

Maternal absence and stability of individual differences in CSF 5-HIAA concentrations in rhesus monkey infants.

Objective: Early life events often lead to deficits in CNS serotonin function, which underlie a number of reoccurring psychopathological disorders. Studies using rhesus macaques have demonstrated that early maternal deprivation reduces CNS serotonin turnover, as measured by cisternal CSF 5-HIAA concentrations. In addition, individual differences in CSF 5-HIAA remain stable from the first year of life through adulthood.

Social withdrawal behaviors in nonhuman primates and changes in neuroendocrine and monoamine concentrations during a separation paradigm.

This study investigated relationships between withdrawal behaviors in rhesus macaques and changes in monoamine metabolite and endocrine concentrations during repeated psychosocial stress. Rhesus monkeys (N = 71) experienced maternal separation in which four separations took place during four consecutive weeks. Behavioral observations were made, as well as plasma concentrations of cortisol and cerebrospinal fluid concentrations of the serotonin, dopamine, and norepinephrine metabolites were obtained.

Monoamine oxidase A gene promoter variation and rearing experience influences aggressive behavior in rhesus monkeys.

Background: Allelic variation of the monoamine oxidase A (MAOA) gene has been implicated in conduct disorder and antisocial, aggressive behavior in humans when associated with early adverse experiences. We tested the hypothesis that a repeat polymorphism in the rhesus macaque MAOA gene promoter region influences aggressive behavior in male subjects.

Methods: Forty-five unrelated male monkeys raised with or without their mothers were tested for competitive and social group aggression.

Interaction between serotonin transporter gene variation and rearing condition in alcohol preference and consumption in female primates.

Background: Serotonin neurotransmission and limbic-hypothalamic-pituitary-adrenal (LHPA) axis hormones are thought to be involved in the reinforcement of alcohol intake and contribute to the risk for alcoholism. In humans and macaques, a promoter polymorphism that decreases transcription of the serotonin transporter gene is associated with anxiety and altered LHPA-axis responses to stress, and in female macaques, exposure to early-life stress alters LHPA-axis activation in response to alcohol. We wanted to determine whether serotonin transporter gene promoter variation (rh-5HTTLPR) and rearing condition would interact to influence alcohol preference in female rhesus macaques.

Sexual dichotomy of an interaction between early adversity and the serotonin transporter gene promoter variant in rhesus macaques.

A polymorphism in the human serotonin transporter gene promoter (5-HTTLPR) is associated with anxiety and increased risk for developing depression in the face of adversity. Here, we report that among infant rhesus macaques, an orthologous polymorphism (rh5-HTTLPR) interacts with adversity in the form of peer rearing to influence adrenocorticotropic hormone (ACTH) response to stress and, further, that this interaction is sexually dichotomous. ACTH responses to separation are higher in l/s than in l/l males.

Rearing condition and rh5-HTTLPR interact to influence limbic-hypothalamic-pituitary-adrenal axis response to stress in infant macaques.

Background: In humans and macaques, a promoter polymorphism that decreases transcription of the serotonin transporter gene is associated with anxiety. Serotonin transporter gene disruption in rodents produces anxious animals with exaggerated limbic-hypothalamic-pituitary-adrenal (LHPA) responses to stress. We wanted to determine whether serotonin transporter gene promoter variation (rh-5HTTLPR) and rearing condition would interact to influence endocrine responses to stress in infant rhesus macaques.

Neurobehavioral deficits in neonatal rhesus monkeys exposed to cocaine in utero.

In spite of significant efforts, the neurobehavioral deficits in infants born from cocaine-abusing mothers have not been clearly defined. In the present study, we examined the presence of these abnormalities in a rhesus monkey model of prenatal cocaine exposure using a nonhuman primate adaptation of the Neonatal Behavioral Assessment Scale (NBAS). Pregnant monkeys (n = 14) received 10 mg/kg cocaine twice a day orally (in fruit treats) from the 40th through 102nd postconception days (PCD40-PCD102), which is the period of cerebral cortical neuronogenesis (approximately second trimester).

Serotonin transporter gene variation is associated with alcohol sensitivity in rhesus macaques exposed to early-life stress.

Background: Decreased sensitivity to alcohol has been demonstrated to be a predictor of alcoholism in humans, and variation in the gene-linked polymorphic region of the serotonin transporter (5-HTTLPR) is associated with the response to the motor-impairing effects of alcohol. In a nonhuman primate model of excessive alcohol intake, we have shown that decreased serotonin turnover is associated with both lower initial sensitivity to alcohol and higher prospective alcohol consumption using rhesus macaques. In addition, we have demonstrated that macaques separated from their mothers and reared in peer-only groups are more likely to consume alcohol as adults.

Fatty acid formula supplementation and neuromotor development in rhesus monkey neonates.

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is highly concentrated in CNS tissues. Although breast milk contains the fatty acids DHA and arachidonic acid, infant formulas marketed in North America do not contain these nutrients. The potential deleterious effects of rearing infants with formulas devoid of these nutrients was assessed by comparing nursery-reared rhesus macaque infants (Macaca mulatta) fed standard formula with infants fed standard formula supplemented with physiologically relevant concentrations of DHA (1.

Behavioral and Physical Concomitants of Congenital Hydrocephalus in a Rhesus Macaque (Macaca mulatta) Neonate.

A colony-born male rhesus monkey neonate was assigned to an ongoing protocol assessing behavioral and physiologic development in nursery-reared infants. It was sacrificed at day 20 because of poor weight gain, inability to self-feed, and generalized weakness. An asymmetric internal hydrocephalus was the only notable gross finding at necropsy.

CBC and serum chemistry differences between Indian-derived and Chinese-Indian hybrid rhesus monkey infants.

Hematological and clinical biochemistry measures are commonly utilized as indicators of the health status of nonhuman primates. Among individuals in a population of a given species, there may be considerable variation in these parameters. Still wider variation may be found among different strains or subspecies of some orders.

Laboratory assessment of temperament and environmental enrichment in rhesus monkey infants (Macaca mulatta).

This study investigated the combined effects of early temperamental characteristics and environmental enrichment on a variety of developmental measures in nursery-reared rhesus monkey infants. Twenty-three infants, reared in either standard laboratory cages or enriched environments, were tested during the 1st month of life for interactive, motor, and temperamental capabilities and characteristics. At 8 months of age, all subjects were assessed on a second series of tests designed to measure their problem-solving skills, motor capabilities, and temperamental responses under challenge.

Inanimate environmental enrichment for group-housed rhesus macaque infants.

The behavior of peer-reared infant rhesus macaques raised in enriched and nonenriched housing conditions was examined in order to evaluate the utility and effectiveness of object enrichment in a group housing setting. Environmental enrichment consisted of apparatuses designed to promote motor activity and to provide response-contingent feedback. Four animals in each condition were tested over a 14-month period.