Water metabolic parameter changes in rhesus monkeys during exposure to prolonged restriction of motor activity

The objective of this investigation was to determine the effect of prolonged restriction of motor activity (hypokinesia [HK]) on several parameters of water metabolism in primates. The studies were performed on 12 rhesus monkeys aged 4–5 yr (5.10–6.85 kg) during the hypokinetic period of 90 d and during the prehypokinetic period of 30 d. They were divided into two equal groups: the first group was placed under ordinary vivarium conditions (vivarium control animals) and the second group was subjected to 90 d of HK (hypokinetic animals). For the simulation of the hypokinetic effect, the primates were immobilized on their abdomens in special tables. The legs of the monkeys were immobilized with hip and knee joints extended. The primates retained freedom of movement at elbow, wrist, and ankle. During the preexperimental period of 30 d and during the experimental period of 90 d, the following variables were determined: body weight, total body fluid content, specific total body fluid, mean fluid consumed and eliminated in urine, specific plasma resistance, hematocrit level, and plasma concentrations of sodium (Na) and potassium (K). In the hypokinetic primates, body weight decreased significantly when compared to the controls. Mean fluid intake, total body fluid, and specific total body fluid decreased, whereas mean daily fluid loss and specific mean daily fluid elimination increased significantly. Specific plasma resistance, hematocrit level, and plasma electrolyte concentrations increased significantly when compared to the control primates. It was concluded that prolonged restriction of motor activity induces significant changes in water metabolic parameters of primates leading in decreased total water content of the body.     

Thermoregulatory adjustments in squirrel monkeys exposed to microwaves at high power densities

The present study was undertaken to investigate the thermal adjustments of squirrel monkeys exposed in a cold environment to relatively high energy levels of microwave fields. The animals (Saimiri sciureus) were equilibrated for 90 min to a cool environment (Ta = 20 degrees C) to elevate metabolic heat production (M). They were then exposed for brief (10-min) or long (30-min) periods to 2,450-MHz continuous-wave microwaves. Power densities (MPD) were 10, 14, 19, and 25 mW/cm2 during brief exposures and 30, 35, 40, and 45 mW/cm2 during long exposures (rate of energy absorption: SAR = 0.15 [W/kg]/[mW/cm2]). Individual exposures were separated by enough time to allow physiological variables to return to baseline levels. The results confirm that each microwave exposure induced a rapid decrease in M. In a 20 degree C environment, the power density of a 10-min exposure required to lower M to approximate the resting level was 35 mW/cm2 (SAR = 5.3 W/kg). During the long exposures, 20 min was needed to decrease M to its lowest level. Cessation of irradiation was associated with persistence of low levels of M for periods that depended on the power density of the preceding microwave exposure. Vasodilation, as indexed by changes in local skin temperature, occurred at a high rate of energy absorption (SAR = 4.5 W/kg) and was sufficient to prevent a dramatic increase in storage of thermal energy by the body; vasoconstriction was reinstated after termination of irradiation. Patterns of thermophysiological responses confirm the influence both of peripheral and of internal inputs to thermoregulation in squirrel monkeys exposed to microwaves in a cool environment.     

Four-year study of controlled timed breeding of rhesus monkeys (Macaca mulatta)

As part of the timed breeding colony at Tulane National Primate Research Center, exogenous progesterone administration (5 mg/day for 10 days) has been used to select conception dates by inducing artificial luteal phases in female rhesus monkeys. A retrospective analysis of data obtained during four breeding seasons (1998-2001) revealed that conceptions occurred an average of 18 days after the last administration of progesterone. The age of the female to be bred, previous pregnancy history, and timing of breeding during the breeding season were determined to be critical factors in the success of the procedure. The benefit of this method of timed breeding is that it does not require tracking of menstrual cycles, which can be labor-intensive and requires that animals be monitored several months in advance of breeding to determine each female's individual cycle length. It also provided an efficient use of breeding-age males.     

Extinction of rhesus monkeys (Macaca mulatto) in Xinglung,North China

An isolated population of rhesus monkeys living in Xinglung County, north of Beijing (latitude 40⪤gree N), was a natural population at the northernmost range of the species in Asia. Rhesus had been reported there at the end of the last century, based on a few specimens, but were not well known by zoologists until the beginning of the 1960s. The population remained approximately 50–60 individuals in the 1960s but then declined to only 4 or 5 monkeys about 5 years ago. It has been confirmed by local hunters and two recent field trips that the population is now probably extinct. As a result, the northern extent of the remaining natural range of the rhesus macaque in Asia has dropped 650 km southward to the Jiyuan Nature Reserve on the border of Hunan and Shanxi provinces, just north of the Yellow River.     

Further characterization of the G blood group system of rhesus monkeys

We describe a new antiserum that has the unique ability to distinguish homozygous from heterozygous genotypes in the G blood group system of rhesus monkeys. With this new typing serum (reagent), all 10 possible genotypes in this system can be distinguished and the utility of blood typing for genetic studies has been greatly increased.     

Seasonal breeding in rhesus monkeys: Influence of the behavioral environment

The accepted model of breeding seasonality in rhesus monkeys states that females become reproductively active in response to an environmental cue and that males become sexually active in response to ovulating females. This model must be modified to include direct responses of the male to the physical environment, endocrine responses of males to sexual activity, and responses of the female to the sexual activation of fellow group members. The complex set of social stimuli that influences the breeding readiness of both sexes may serve to delimit more precisely the annual periods of conception and birth than would be the case if each individual responded only to the changing physical environment.     

Behavioral effects of enrichment on pair-housed juvenile rhesus monkeys

Among captive primates, inanimate environmental enrichment can lead to measurable changes in behavior indicative of an improvement in psychological well-being. Although this has been demonstrated repeatedly for singly caged primates, the relationship is not as well studied for pairhoused animals. Study of the pair-housed setting has become increasingly relevant because of the social housing mandate of the Animal Welfare Act regulations. We therefore observed 68 juvenile rhesus monkeys born in 1988 and 1989 and living in mixed-sex pairs from the ages of 2 to 3 years. All pairs were compatible. Half of the pairs received two types of enrichment, while the remaining pairs served as controls. Enriched and control juvenile subjects differed in the amount of time that they spent being inactive, playing, and drinking, but did not differ in the amount of time they spent interacting with their partner. Grooming and play were the two most common socially directed activities in both groups, a species-appropriate pattern. Males played more and vocalized less than did females. Overall, enriched and control subjects spent equivalent amounts of time located within a social distance of one another, but there was some difference between groups in allocation of behaviors while near the pairmate. Environmental enhancers were frequently utilized, and led to relatively small changes in behavior between control and enriched subjects, suggesting that the presence of a partner for juvenile rhesus monkeys acts as a form of enrichment that may dilute the effects of inanimate environmental enhancements. © 1994 Wiley-Liss, Inc.     

Atretogenic action of estrogen in rhesus monkeys: Effects of repeated treatment

The effects of 17β-estradiol (E₂), administered in Silastic capsules for 24 hours at intervals of 10 or 14 days, on follicular development and menstrual cycle characteristics were studied in 13 rhesus monkeys. In seven monkeys receiving E₂ at l0-day intervals for 50 treatment periods, new follicles frequently developed between treatments but usually regressed. In seven instances, the follicles persisted longer than expected but were steroidogenically suppressed and regressed spontaneously. Ovulation occurred in only two instances. In six monkeys receiving E₂ at 14-day intervals, new follicles developed regularly, with seven ovulations occurring in 37 treatment periods. A persistent anovulatory follicle was noted in only one instance. Menstruation occurred with equal frequency, and the interval from treatment to onset of menstruation was not significantly different regardless of treatment or the occurrence of ovulation; the intervals between menstruation approximated those of normal menstrual cycles. In general, following termination of treatment, menstrual cycles returned to normal quickly. These data indicate that E₂ administered intermittently at 10-day intervals effectively suppresses ovulation, and they provide new insight into the actions of E₂ on folliculogenesis in primates.     

安徽恒河猴的微生物学和寄生虫学检测

对安徽省实验猕猴中心的安徽恒河猴进行了微生物（包括病毒和病原菌）和寄生虫检测。对恒河猴的病毒检测结果发现,猕猴疱疹病毒1型（BV）和猴痘病毒（SPV）抗体的阳性率分别为20．7％（6／29）和10．0％（2／20）,20只恒河猴中没有发现猴反转录D型病毒（SRV）、猴免疫缺陷病毒（SIV）和猴T细胞趋向性病毒Ⅰ型（STLV—1）的抗体。5只受检的人工繁育的安徽恒河猴没有感染沙门菌、皮肤病原真菌、志贺菌和结核分枝杆菌的这四种病原菌。肉眼检测恒河猴体表,未发现体外寄生虫。39份人工繁殖的恒河猴粪便样品的总寄生虫感染率为38．5％,检测到溶组织内阿米巴和5种蠕虫（粪类圆线虫、猴结节线虫、绦虫、钩虫、蛔虫）,感染率最高的是粪类圆线虫和猴结节线虫。本次调查表明,安徽恒河猴无特殊疾病,健康状况基本良好,可以建立普通级的实验恒河猴,实现安徽恒河猴的实验动物化。     

Sterilization and its behavioral effects on free-ranging female rhesus monkeys (Macaca mulatta).

In order to control population growth rates, a decision was made to sterilize most of the free-ranging, wild rhesus macaque females of Silver Springs, Florida. Between October 1987 and March 1988, the five females who had been sterilized and released in the fall of 1986 were matched with five intact females in a behavioral study. While there were differences between the behaviors of the sterilized and intact females, the differences can be attributed more to differences in age, rank, and other factors than to the sterilization. Clinical data collected and reported on the monkeys is unremarkable.     

Operant behavior and colonic temperature of Macaca mulatta exposed to radio frequency fields at and above resonant frequencies

Five food-deprived rhesus monkeys were exposed to 225-MHz continuous-wave, and 1.3-GHz, and 5.8-GHz pulsed radiation to determine the minimal power densities affecting performance. The monkeys were trained to press a lever (observing-response) thereby producing signals that indicated availability of food. In the presence of the aperiodically appearing food signals, a detection response on a different lever was reinforced by a food pellet. Continuous, stable responding during 60-min sessions developed and was followed by repeated exposures to radiofrequency radiation. The subjects, restrained in a Styrofoam chair, were exposed to free-field radiation while performing the task. Colonic temperature was simultaneously obtained. Observing-response performance was impaired at increasingly higher power densities as frequency increased from the near-resonance 225 MHz to the above-resonance 5.8 GHz. The threshold power density of disrupted response rate at 225 MHz was 8.1 mW/cm²; at 1.3 GHz it was 57 mW/cm², and at 5.8 GHz it was 140 mW/cm². These power densities were associated with reliable increases in colonic temperatures above sham-exposure levels. The mean increase was typically in the range of 1°C, and response-rate changes were not observed in the absence of concomitant temperature increases. In these experiments increase of colonic temperature was a much better predictor of behavioral disruption than was either the power density of the incident field or estimates of whole-body-averaged rates of energy absorption.     

Social enrichment of the environment with infants for singly caged adult rhesus monkeys

The practicability of social enrichment for singly caged adult rhesus monkeys was examined. Twenty-nine weaned rhesus monkey infants were removed from breeding troops to avoid overcrowding and were placed with unfamiliar singly caged adults. An adult-infant pair was considered compatible when (1) the two animals started huddling with each other within the first 5 days after pair formation and (2) the infant showed no signs of depression and took its share from a limited amount of favored food. Adult-infant pairs were compatible in 90% (26/29) of cases. Compatibility depended neither on the sex, age, and origin of the adult nor on the sex of the infant. There was no evidence that partners lost interest in each other during 7–11 months of follow-up observations. Three adults exhibiting stereotypical behavior abandoned their peculiar habits after they had lived with their young companions for 4 months. It was concluded that the often-heard notion that rhesus monkeys are highly aggressive should not prevent simple attempts to provide singly caged animals with a companion.     

Seasonal rank changes for adolescent and subadult natal males in a free-ranging group of rhesus monkeys

Changes in dominance rank for adolescent and subadult natal males in a semi-free-ranging rhesus macaque group were seasonal. Three 4-year-old natal males of the highest-ranking matriline occupied high ranks in the adult male dominance hierarchy during the premating period. In the mating season they dropped in rank, and this decrement was related to a concomitant drop in their alliances. After the mating season, these males rose in rank along with their two 3-year-old kin to occupy ranks 2–5 and 7–8 in the adult male dominance hierarchy. Three-year-old natal males of matrilines lower ranking than first did not become integrated into the hierarchy at this time.     

Calcium,magnesium, and phosphorus content of hair from two populations of rhesus monkeys

The use of hair for the assessment of human mineral nutritional status is controversial, yet has potential because of the ease of collection and storage, and the high concentration of minerals in hair. This study generated baseline values for hair macromineral content in the most commonly used primate model for human nutrition and disease, the rhesus monkey. Hair digests from monkeys in Maryland (n=98) and Puerto Rico (n=208) were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Significant differences existed between the two populations for hair calcium (Ca), magnesium (Mg), and phosphorus (P) (P<0.01,P<0.001,P<0.02). Male hair had higher concentrations of Mg in specimens from the Puerto Rican population (P<0.001), whereas hair phosphorus was higher in female hair (P<0.02). There were no significant differences attributable to pregnancy status. Differences in hair content attributable to categorical age were found for Ca and Mg (P<0.001,P<0.01). Significant location differences paralleled dietary differences. These values therefore can be considered reference ranges for hair Ca, Mg, and P for free-ranging and caged rhesus monkeys. Preliminary reports of portions of these data were presented at the 69th Annual Meeting of the Federation of American Societies for Experimental Biology, April 1982, New Orleans, LA (B. M. Marriott, J. C. Smith, R. Jacobs, A. O. Jones, M. J. Kessler, and R. Rawlins,Fed. Proc. 41:770 [1982]) and in a symposium at the 6th Annual Meeting of the American Society of Primatologists, 1983, East Lansing, MI (B. Marriott, J. C. Smith, R. Jacobs, A. O. Lee Jones, R. Rawlins, and M. J. Kessler,Am. J. Primatol. 4(3):157 [1983]; B. Marriott, J. C. Smith, Jr., R. M. Jacobs, A. O. Lee Jones, R. Rawlins, and M. J. Kessler, inThe Cayo Santiago Macaques, R. Rawlins and M. J. Kessler, eds., SUNY Press, Albany, NY, pp. 219–231 [1986]).     

Observations of increased activity and tool use in captive rhesus monkeys exposed to troughs of water

This study investigated the effects of water troughs on nonhuman primates housed in a captive environment. Two groups of rhesus monkeys (Macaca mulatta) were exposed to water-filled troughs under three conditions: (1) standing water, (2) running water, and (3) a replication of standing and running water with novel objects. The effects of water exposure were assessed using a pretest phase (baseline), test phase (trough present), and posttest phase (baseline) design for each of the three conditions. Standing water produced different effects from running water. Monkeys were more active in the presence of standing water (higher levels of exploration and lower levels of social contact and grooming) than during baseline observations. In contrast, they were significantly more passive during the running water condition (higher levels of social contact) than baseline. Neither physical condition nor responses to dominance testing varied systematically over phases or between conditions. Tool use was observed during the standing water phases of Conditions 1 and 3. Three females from one group used a variety of cup-like containers as drinking utensils. A larger number of animals used the trough to soak chow prior to ingestion, and virtually all of the animals used the trough as a drinking source. These results suggest that exposure to water sources may elicit a broad spectrum of species-typical activity and may be a simple and inexpensive way to enrich the environment of captive rhesus monkeys. © 1993 Wiley-Liss, Inc.     

Effects of puzzle feeders on pathological behavior in individually housed rhesus monkeys

Self-injurious behavior (SIB) occurs in about 10% of individually housed monkeys. Monkeys with SIB bite their own bodies frequently, occasionally inflicting wounds as a result. At present, there is no standard treatment for this phenomenon. We examined the effectiveness of puzzle feeders in alleviating SIB in monkeys with a veterinary record of self-inflicted wounding. Two groups of monkeys (SIB and controls) were exposed to puzzle feeders for a 6 week period. Three levels of maze difficulty were examined. All monkeys used the feeders, but manipulation was confined to a brief period immediately after the feeders were loaded each day (1000 h) and was infrequent during the later sampling periods (1100 and 1400 h). The most difficult maze yielded a slight increase in usage at 1100 h. During the puzzle feeder phase, whole body stereotypies, including pacing and rocking, were reduced substantially in all monkeys at 1000 h when feeder manipulation was at its highest. However, self-biting in the SIB group was unchanged. Some monkeys actually bit themselves while manipulating the feeder. Long-term effects on abnormal behavior were assessed by comparing behavior during the feeder phase to baseline periods and to a phase in which the monkeys were provisioned with treats placed directly into their food box. Whole body stereotypies, including pacing, were reduced during both treatment phases; however, the reduction was associated only with the 1000 h observation. Puzzle feeders were more effective than treats alone in alleviating whole body stereotypies. Self-biting was unchanged through all phases. Puzzle feeders are beneficial from the perspective of eliciting manipulation. They also yield transient reductions in whole body stereotypy, an effect that does not extend beyond the direct manipulation of the feeder. Puzzle feeders are ineffective in alleviating self-injurious behavior. Am. J. Primatol. 46:213–227, 1998. © 1998 Wiley-Liss, Inc.     

Infant-directed behavior in young rhesus monkeys: Sex differences and effects of prenatal androgens

Young (3–4 years old) laboratory-reared rhesus monkeys were observed in five 15-minute tests with 1–15-day-old infants. Males and females were equally likely to investigate infants. Females communicated more with infants by grin-lipsmacking and gurgling–-gestures that were not shown by any males. More females presented the ventrum to infants than did males. Females contacted infants more than did males by grooming, crouching over, and having full body contact with them. To see whether prenatal androgens produced the male pattern of response, we conducted similar tests with pseudohermaphrodites (prenatally androgenized genetic females) and neonatally castrated males. On most sexually dimorphic behaviors, pseudohermaphrodites behaved more like females than like males. Castrated males, like females and pseudohermaphrodites, crouched over infants more than did intact males. Castrated males differed from females only on one infant-directed response, the grin-lipsmack. These comparisons showed that defeminization of the repertoire of infant-directed responses was measurable only in intact males. We conclude accordingly that prenatal androgens alone are not responsible for defeminization of this repertoire and that a contribution from postnatal androgens is likely to be necessary.     

Brief communication: linear enamel hypoplasia and the shift from irregular to regular provisioning in Cayo Santiago rhesus monkeys (Macaca mulatta)

This study investigates changes in the prevalence of linear enamel hypoplasia (LEH) before and after the shift from irregular to regular provisioning in the Cayo Santiago rhesus monkey population. Prior to 1956, monkeys on this island colony did not receive consistent provisions, and were reported to be in poor health (Rawlins and Kessler [1986] The Cayo Santiago Macaques; Albany: State University of New York Press). A regular provisioning program, instituted in August 1956, resulted in the improved health of individuals and the growth of the population (Rawlins and Kessler [1986] The Cayo Santiago Macaques; Albany: State University of New York Press). LEH, a developmental defect of enamel, is a sensitive indicator of systemic physiological stress (Goodman and Rose [1990] Yrbk. Phys. Anthropol. 33:59-110). It was therefore hypothesized that the prevalence of LEH would be higher in monkeys who were irregularly provisioned than in monkeys who experienced regular provisioning. To test this hypothesis, teeth were examined for LEH in a sample of 181 female rhesus monkeys. The results support the hypothesis: the mean number of defects was statistically significantly higher in the preprovisioned group than it was in the postprovisioned one. When LEH prevalence was assessed using only defects occurring on antimeric pairs, the preprovisioned group again had a higher prevalence than the postprovisioned one, although the difference was not statistically significant, most likely because of the reduced sample size. The results of this study indicate that changes in LEH prevalence, at least in this population of rhesus monkeys, are associated with changes in nutritional status.     

Confirmatory factor analysis of personality structure in adult male rhesus monkeys (Macaca mulatta)

Reports from different laboratories have suggested that nonhuman primates have somewhat similar dimensions of personality. To date, however, no attempts have been made to statistically replicate a specific factor structure. In the present report, two independent observers recorded the behavior of 58 adult male rhesus monkeys, and then rated the animals with the use of a 50-item personality instrument. A confirmatory factor analysis (CFA) of the ratings resulted in the replication of a previously described four-factor personality structure [Maninger et al., American Journal of Primatology 61:73-83, 2003]. The first two dimensions-Sociability and Confidence-showed strong loadings and are similar to Affiliation and Agency dimensions in humans. The remaining dimensions-Equability and Irritability-were less clear, and it is possible that additional traits will have to be identified before a more robust structure can be established for these dimensions.