Female Pigtail Macaques Research Articles

Attributes and validity of dominance hierarchy in the female pigtail macaque

A group of six unrelated female pigtail macaques,Macaca nemestrina, of the same age, was studied in captivity over a period of five years. The animals were observed under six different situations, following changes in the social composition of the group. The following social interactions were recorded: withdrawal, attack, threat, presentation, mount, and grooming. Although behavioural rates varied for each period, their distribution network was remarkably consistent. Each subject could be assigned a rank, which remained stable over the six periods.

Postnatal growth and skeletal maturation of experimental preterm macaques (Macaca nemestrina)

The growth and skeletal maturation of nine preterm female pigtailed macaques (Macaca nemestrina) obtained by C-section at less than or equal to 155 postconceptional days were followed through six months of age. At C-section they were of normal size and maturation for gestational age. Compared with 50 normal females born at term (mean = 173 +/- 6.4 postconceptional days), preterm infants were also of normal size at term, but delayed in skeletal maturation, requiring about one month to achieve the standard.

Constructing an Instrument to Measure the Rate of Aging in Female Pigtailed Macaques (Macaca Nemestrina)

To develop a battery of innocuous tests measuring individual differences in the rate of biological aging, longitudinal data were gathered on 28 biochemical, physiological, and morphological characteristics of 40 adult female pigtailed macaques. The change in each variable over time, i.e., the beta coefficient of linear regression, was calculated for each animal, and a matrix of correlations among the variables was constructed. Eight variables correlated well with the first principal component of the matrix. These variables (rate of fingernail growth, blood lymphocytes, mean corpuscular hemoglobin, immunoglobulin A, and serum sodium, chloride, total protein, and creatinine) represented the best subset of the potential biomarkers analyzed to produce an index covering a range of morphologic and functional systems that change with age. A similar set representing a wider range of systems and measured over a larger fraction of the life span should provide a valid index of an individual's rate of biological aging.

Ovarian Cyclicity, Hormones, and Behavior as Markers of Aging in Female Pigtailed Macaques (Macaca nemestrina)

Age-related differences in reproductive function were studied to identify variables suitable for a battery of noninvasive tests used to measure aging rate. Twenty-seven adult female pigtailed macaques, ranging in age from 8 to 31 years, were studied in a cross-sectional design. Perineal tumescence, menses, and activity in the home environment were recorded daily. Sexual behavior, when paired with unfamiliar males of three age groups, was observed six times in the early follicular phase of two ovarian cycles. Estradiol, LH, and FSH were measured twice during the same time period. Of the behavioral measures, mount, present, and activity were found to be lower in old than in young females. Of the physiological measures, ovarian cyclicity was less regular, estradiol was lower, and FSH and LH were higher in old compared to young females. Correlations between measures suggested two dimensions of reproductive function, a behavioral dimension and a physiological dimension.

The influence of rank on affect perception by pigtailed macaques (Macaca nemestrina).

Previous studies of affect perception in nonhuman primates have involved young animals and/or manipulations of early experience. Based upon data suggesting that middle-ranked monkeys in small social groups show patterns of behavior different from their low- or high-ranked counterparts, the current study examined the role of social rank in affect perception by normally reared, adult female pigtailed macaques. Employing color videotapes as the presentation medium, we observed animals as they watched unfamiliar animals display social (aggressive or submissive) or nonsocial behavior. Virtually all threats were recorded as the subjects watched the submissive presentations, and most submissive signals occurred while watching aggressive behavior tapes. Middle-ranked monkeys were most attentive during all presentations, and levels of disturbance behavior were related to rank of the watcher and type of presentation observed. The results suggest that dominance status is an influence in the process of affect perception.

Luteinizing hormone regulation in the monkey (Macaca nemestrina): failure of testosterone and dihydrotestosterone to block the estrogen-induced gonadotropin surge.

In contrast to females, intact male monkeys do not release luteinizing hormone (LH) after an acute estrogen challenge; orchidectomized males, on the other hand, do release LH in response to estrogen. To examine whether physiological levels of testosterone (T) or dihydrotestosterone (DHT) could effect a blockade of the estrogen-induced LH surge in the female monkey, we treated 4 long term oophorectomized female pigtailed macaques (Mocaca nemestrina) for 10 days with Silastic capsules containing T. These capsules produced T blood levels of 6.80 ± 0.97 ng/ml, which approximated the normal range (3.44-15.75 ng/ml). In addition to T or DHT, in this and subsequent experiments all gonadectomized animals received a long term (> 1 week) pretreatment with a 1.5 cm Silastic capsule containing estradiol-1 7j3. This treatment, designed to titrate the high postgonadectomy levels of LH into approximately the intact range, was continued throughout the entire experimental period. The monkeys were then challenged with estradiol benzoate (EB) (50 pg/kg, s.c.) and bled twice daily for 6 days; each responded with a typical LH surge. In a second trial, the animals were treated with T for 6 weeks and then challenged with EB; again, each responded with an LH surge. In a third trial, each monkey was treated with T for 8 weeks combined with DHT for the final 2 weeks. This treatment also failed to block the EB-induced LH surge. We then treated 3 long term orchidectomized male pigtailed macaques with T for 10 days and then challenged them with EB; each animal responded with a normal LH surge. These data demonstrate that 1) neither T nor DHT can block the EB-induced LH surge in the oophorectomized female and 2) T in the physiological range can not effect a blockade of the EB-induced surge in the orchidectomized male.

Behavioral correlates of reproductive success in a pigtail macaque breeding colony

Data on social and spatial behavior from a sample of 21 female pigtail macaques (Macaca nemestrina) were analyzed to identify behavioral correlates which could be used to predict reproductive success, problem pregnancies, and adult female mortality in a primate breeding colony in the subsequent year. Two spatial measures of sociability, amount of time and number of other individuals involved in sitting associations, were found to be related to future adult and infant survivorship.