Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist widely used in pediatric anesthetic and therapeutic practices and veterinary medicine. Previous evidence suggests that exposure to ketamine during sensitive periods of development results in neural apoptosis and atypical behavior. Since monoamine neurotransmitters play important roles in prenatal and early postnatal neural development, and since previous work suggests ketamine can inhibit monoamine transporters, we hypothesized that there would be behavioral consequences of prenatal and early postnatal exposure to ketamine moderated by genotype of the promoter in the monoamine oxidase-A (MAOA) gene. From a large sample of animals (N = 408), we compared groups of rhesus monkeys that had experienced a single exposure to ketamine during prenatal development, an exposure during prenatal development and one postnatal exposure, a postnatal exposure with no prenatal exposure, and no exposures. Animals were classified by putative activity levels for the MAOA genotype and were tested between 3 and 4 months of age on a battery of behavioral tests. Results suggested that animals exposed to ketamine postnatally, at a dose typically used for sedative effects that also had the low-activity variant of MAOA performed poorly on a visual memory test compared to animals with the high-activity variant of the MAOA gene.

There is a general consensus that perinatal experiences help to shape infant behavior; however, relatively little is known about the effects of prenatal experience on postnatal phenotype in non-human primates. The current study sought to take advantage of a naturally occurring incident in a captive population of rhesus monkeys. Following a matrilineal overthrow in an outdoor field cage, pregnant female rhesus macaques were relocated from outdoor to indoor housing. Using data collected from the California National Primate Research Center's Biobehavioral Assessment Program, we assessed infants born to mothers that were in their first or second trimester of pregnancy during the overthrow and relocation, and compared their data with that of animals from two control groups born in the same year: indoor mother raised infants and field cage reared infants. Our results suggest that the experience of an overthrow and relocation during the first trimester elevated postnatal emotional responsiveness, while the same experience in the second trimester resulted in modified HPA axis regulation, elevated glucocorticoid output following maternal separation, and lower hematocrit levels compared to control groups. These data add to a growing body of literature that prenatal experiences represent a significant contribution to postnatal phenotypic variability. Findings such as ours have implications for studies in captive management and the management of captive rhesus monkey populations. Am. J. Primatol. 78:895-903, 2016. © 2016 Wiley Periodicals, Inc.