Weight and size of the placenta in cynomolgus monkeys (Macaca fascicularis).

A gross anatomical survey of the placental development was carried out in 24 cynomolgus monkeys (Macaca fascicularis) of 4, 5, 6, 7, 8, 9, 10, 15 and 20 weeks of gestational age. Eight of the 24 placentas examined were found to be single discoidal and the remaining 16 bidiscoidal. The weight and size of placentas of each animal were measured. The average weight of the 20th week placentas was about 94 times heavier than that of the 4th week ones; the average diameter of the former was about 5 times larger than that of the latter.     

Changes of the uterine size during pregnancy in cynomolgus monkeys (Macaca fascicularis) (author's transl)]

This paper describes changes in the uterine size during the normal course of pregnancy in cynomolgus monkeys. Twenty-four females which had conceived by 3-day individual mating with a male were laparotomized 4,5,6,7,8,9,10,15 and 20 weeks after conception. The width, thickness and length of uterus were measured by a pair of callipers. Them, the uterine volume was estimated by the formula, V = 4/3 piab2 (a, b: uterine length x 1/2, uterine width x 1/2). The increase in the uterine width (y) during pregnancy could be expressed as a linear equation: y = 0.35x + 1.48 (x: weeks after conception). The thickness of pregnant uteri could be represented by a a linear equation: y = 0.36x + 1.40. From the 4th to the 20th week of pregnancy, the uterine length increased along a straight line expressed as a linear equation: y = 0.58x + 1.14. Except for nonpregnant uteri, the change in the uterine volume after pregnancy could be expressed as a linear logarithmic equation: log y = 2.319 log x -0.315. These 24 pregnant monkeys had followed the normal course of gestation until the time of laparotomy without any abnormality in their fetuses of their placentas, indicating that the values obtained throughout this study are of practical use for taking care of pregnant cynomolgus monkeys.     

Presence of antibody to Cyno-EBV in domestically bred cynomolgus monkeys (Macaca fascicularis).

The presence of an antibody to the Cyno-EBV was studied with Cyno-EBV bearing cell line (Ts-B-9) as antigen in 186 domestically bred cynomolgus monkeys (Macaca fascicularis) ranging in age from birth to 18 yr as well as in 20 adult (older than 10 yr) cynomolgus monkeys of wild origin. The maternal antibody to Cyno-EBV persisted for less than four mo after birth in infant monkeys. After one yr of age, all the domestically bred monkeys were consistently positive for Cyno-EBV. In the monkeys of wild origin also, the anti-Cyno-EBV antibody was detected without exception. Antibody titers in adult monkeys varied from 1:80 to 1:640.     

Influence of housing conditions on pregnancy outcome in cynomolgus monkeys (Macaca fascicularis)

Female cynomolgus monkeys (Macaca fascicularis) were kept under 3 different housing conditions: individually in type A cages (45 X 45 X 60 cm), individually in type B cages (70 X 70 X 100 cm) and as couples in type B cages. Primigravida did not show early embryonic mortality, differing significantly from 11.5% early losses in multigravida. Early embryonic mortality was not affected by housing condition. Further reproductive failure rates did not differ significantly for primigravid (18.5%) and multigravid females (24.0%), though abortion tended to occur more frequently in primigravida. Perinatal mortality (16.1%) accounted for most of the losses under each housing condition. More successful pregnancies (90%) were recorded for females housed individually in type B cages than for females housed in type A cages (68%). About 50% of the couples originally established remained until weaning of their infants, yielding 77% viable offspring. For multigravid females statistical evaluation showed a significant effect of housing conditions on reproductive outcome (X2-test 0.01 less than P less than 0.05) that could be entirely attributed to low losses in females housed individually in type B cages. It is concluded that housing conditions can have a profound influence on reproductive success in cynomolgus monkeys.     

Predictors of social status in cynomolgus monkeys (Macaca fascicularis) after group formation

The purpose of the present study was to determine whether various behavioral and hormonal markers obtained in individually housed monkeys would be predictive of social rank following group housing. Body weight, serum cortisol and testosterone levels, and locomotor activity in an open-field apparatus were examined in 20 experimentally naive male cynomolgus monkeys (Macaca fascicularis) while they were individually housed. It was hypothesized that eventual subordinate monkeys would have higher cortisol levels and increased locomotor activity scores. These monkeys were then placed in social groups of four (five pens of four monkeys), and social rank was determined based on outcomes of dyadic agonistic encounters. Body weight correlated significantly with eventual social rank. In general, the heavier the monkey the higher the social rank. Locomotor activity in an open-field apparatus following administration of a low dose of cocaine (0.01 mg/kg, i.v.), which has been shown to increase CNS dopamine, correlated with eventual social rank such that individually housed monkeys with high levels of locomotion were more likely to become subordinate. Serum cortisol and testosterone levels failed to correlate with eventual social rank. Hypothalamic-pituitary feedback sensitivity and adrenal responsiveness were examined by measuring cortisol levels after administration of dexamethasone and following ACTH challenge. Cortisol responses in these tests were not associated with eventual social rank. These results suggest that, in addition to body weight, the level of reactivity in a novel environment after administration of a low dose of cocaine is a potential trait marker for social rank. This trait is apparently not associated with hormone levels, but may involve other CNS mechanisms.     

Spontaneous diabetes mellitus in cynomolgus monkeys (Macaca fascicularis)

Glucose tolerance tests were performed with fourteen cynomolgus monkeys. They were divided into two groups with regard to the serum glucose level at the time of routine health-examination. Nine of them had normal glucose level (below 123 mg/dl, the normal group) and the other five monkeys exhibited hyperglycemia (the abnormal group). Fifty per cent glucose solution was administered into the saphenous vein at a dose of 4 ml/head. Blood samples were taken just before and 5, 10, 20, 30, 60 and 120 minutes after the glucose administration. K-value (K = 0.693/t 1/2 X 100) as the decreasing rate of serum glucose during from 5 to 60 minutes after the administration was calculated. Average K-value for eight monkeys of the normal group was 3.12 +/- 0.48. Both immunoreactive insulin level (IRI) and C-peptide immunoreactivity (CPR) increased just after the glucose administration and began to decrease 5 to 30 minutes after the administration in all the eight animals. Remaining one animal (No. 009) of the normal group showed 1.03 in K-value. For the abnormal group, K-value averaged 0.75 +/- 0.25. IRI was slightly higher in this group than in the 8 monkeys of the normal group. Furthermore, the abnormal group did not show any definite change of a certain trend in IRI and CPR. In conclusion, the former 8 monkeys were judged to be normal in the function of pancreatic beta-cells, and the latter 5 monkeys and No. 009 monkey were judged to be suffering from type II (noninsulin dependent) diabetes mellitus at different stages of the disease.     

The cerebral artery in cynomolgus monkeys (Macaca fascicularis)

Cerebral artery structure has not been extensively studied in primates. The aim of this study was to examine the cerebrovascular anatomy of cynomolgus monkeys (Macaca fascicularis), which are one of the most commonly used primates in medical research on human diseases, such as cerebral infarction and subarachnoid hemorrhage. In this study, we investigated the anatomy and diameter of cerebral arteries from 48 cynomolgus monkey brain specimens. We found three anatomical differences in the vascular structure of this species compared to that in humans. First, the distal anterior cerebral artery is single. Second, the pattern in which both the anterior inferior cerebellar artery and posterior inferior cerebellar artery branch from the basilar artery is the most common. Third, the basilar artery has the largest diameter among the major arteries. We expect that this anatomical information will aid in furthering research on cerebrovascular disease using cynomolgus monkeys.     

CD3 polymorphism in cynomolgus monkeys (Macaca fascicularis)

Cynomolgus monkeys were divided into two groups in terms of the reactivity of their lymphocytes with the FN18 monoclonal antibody, which is directed to the CD3 of rhesus monkeys. It was shown that 24 (12.2%) out of 196 monkeys did not have lymphocytes that reacted with the FN18, although T cells from those animals responded well to mitogenic stimulation. We have determined the nucleotide sequences of the CD3delta, CD3gamma, and CD3epsilon chains and found that two amino acids of the CD3epsilon chain of the FN18 non-reactive monkeys were different when compared with the FN18 reactive monkeys. Our results indicated that the CD3epsilon molecule of cynomolgus monkeys is polymorphic at the epitope level, which is recognized by the FN18 monoclonal antibody.     

Cryopreservation of spermatozoa from cynomolgus monkeys (Macaca fascicularis)

Three egg-yolk diluents, which have been used successfully in cryopreservation of human spermatozoa, were compared for their ability to protect macaque semen against cryodamage. TEST (Tes + Tris + egg yolk), TEST with 20% skim milk (TSM), and egg yolk-citrate (EYC), each with 3 or 5% glycerol were compared using 12 ejaculates from 6 male cynomolgus macaques. Computer-aided analysis of sperm motion was used to determine the percentage motility (%M), curvilinear velocity (VCL), and linearity (LIN) of spermatozoa after thawing. The supravital stain Hoechst 33258 and a fluoresceinated pea lectin were used to determine the % of viable spermatozoa with intact acrosomes. TSM and TEST were superior to EYC in terms of % M and of % viable, acrosome-intact spermatozoa. TSM and TEST produced equivalent VCL and LIN values, while EYC had clearly reduced VCL and LIN. There were no interactions between diluent and glycerol level. The 3% glycerol level gave superior results to 5% glycerol for %M. EYC, which is widely used for cryopreservation of human spermatozoa, was not suitable for cynomolgus monkey semen. Artificial insemination with semen cryopreserved in TSM resulted in a healthy, full-term infant.     

Medroxyprogesterone acetate, aggression, and sexual behavior in male cynomolgus monkeys (Macaca fascicularis).

Medroxyprogesterone acetate (MPA) is used clinically to treat male sex offenders, but there are conflicting reports about its effects on aggression. To investigate these matters in a nonhuman primate, four intact male cynomolgus monkeys were studied in a testing paradigm that involved the presence of a caged, aggression-arousing stimulus male either immediately before or during a pair-test with an ovariectomized, untreated female partner. After two 4-week periods of pretreatment baseline, males received weekly injections of 40 mg MPA either alone (two 4-week treatment periods) or in combination with testosterone replacement with sc implants (one period) and additional daily injections of 2 mg testosterone propionate (two periods). MPA was then withdrawn while testosterone replacement continued (three periods). The testing paradigm was effective in maintaining aggression, especially male-male aggression, for many months. Male-male aggression increased with MPA treatment, and increased further with testosterone replacement, whereas male-female aggression tended to change in the opposite direction. As in earlier studies, MPA decreased both plasma testosterone and male sexual activity, but restoring plasma testosterone levels in treated males failed to restore their sexual activity. MPA therefore has behavioral effects that are not mediated primarily by its suppression of circulating androgens.     

Metabolism and pharmacokinetics of progesterone in the cynomolgus monkey (Macaca fascicularis)

[4-14C]Progesterone was administered to two cycling female monkeys during the luteal phase of the cycle, and blood and urine were sampled over a 24 h period. Progesterone had a volume of distribution of 1.75 +/- 0.3 L/kg, and a plasma elimination clearance of 0.06 +/- 0.03 L/kg/min. In comparison to the human, plasma progesterone binding was greater and progesterone clearance was slower in the cynomolgus monkey. The major unconjugated metabolite in plasma was 20 alpha-hydroxy-4-pregnen-3-one. In urine 6.2% of 14C-steroids were unconjugated, 2.3% of which were [14C]progesterone. Thin-layer chromatography (TLC) of conjugated metabolites in urine revealed that 24% had the mobility of sulfates, 19% that of glucuronides, and 52% were more polar. After hydrolysis of conjugates, a major fraction chromatographed with pregnanediol. However, despite evidence for the presence of a 20 alpha-hydroxyl group, none of the pregnanediol isomers could be identified among these 14C-steroids. Nevertheless, over 80% of urinary metabolites had sufficient analogy to pregnanediol to bind to an antiserum specific for ring D and the C-17 side-chain of pregnanediol.     

Persistent cloaca in a cynomolgus monkey (Macaca fascicularis).

A persistent cloaca was found to occur in a 15-year-old female cynomolgus monkey. This is the first case reported in a nonhuman primate. The embryological basis of this anomaly is discussed, and pertinent anatomical findings in this animal are reported which demonstrate the embryologic defect.     

Pulmonary cestodiasis in a cynomolgus monkey (Macaca fascicularis).

Cestodiasis in primates has been noted historically to occur quite frequently, although tissue damage and clinical signs may or may not be apparent. Larval cestodes, such as hydatid cysts or cysticercus cysts, are known to cause extensive tissue damage, while other larval cestodes, such as tetrathyridia, cause minimal damage to the host. This case history concerns an apparently healthy cynomolgus monkey that was part of a surgical study. During the study, all parameters were normal. The monkey died 3 hours postsurgery. The apparent cause of death was respiratory arrest. At necropsy, it was discovered there were 1- to 3-mm-diameter cysts, which on transection extruded 2- to 5-mm-long larvae. The larvae could not be positively identified; however, they resembled tetrathyridia of Mesocestoides sp.     

Enzootic hepatitis A infection in cynomolgus monkeys (Macaca fascicularis)

During a toxicology study in cynomolgus (long-tailed or crab-eating) monkeys (Macaca fascicularis), a randomly distributed incidence of significantly increased hepatic enzyme activity was observed. Premedication hepatic enzyme activity in all monkeys of this study was normal, but increased alanine aminotransferase (ALT) activity was found in 4 of the 24 animals 2 weeks after initiation of the study and in 10 of 24 at 4 weeks. A drug-related effect was considered unlikely initially because the increases were not doserelated, and a 3-year review of 655 cynomolgus monkeys revealed a 15–20% incidence of increased hepatic enzyme activity. Good correlation was subsequently established between increased hepatic enzyme activity, active hepatitis A virus (HAV) infection, and histomorphologic confirmation of hepatitis (chronic periportal inflammation). Follow-up viral serodiagnostic screening of resident macaques revealed an overall incidence of anti-HAV IgG in 80% (155/193) of cynomolgus and in 70% (14/20) of rhesus monkeys. Serial screening demonstrated that several initially negative monkeys became seropositive for anti-HAV IgG, and a few acquired active infection (anti-HAV IgM). Among newly acquired cynomolgus monkeys, 2.5% (2/80) had an acute HAV infection, and 35% (28/80) eventually tested positive for anti-HAV IgG while quarantined in the primate facility. The characterization of an enzootic HAV infection in incoming monkeys posed a significant risk for the primate colony and handlers. Rigorous sanitation, isolation, and quarantine procedures, including personnel training and additional protective clothing for personnel working in the primate colony, reduced tho potential for transmission and arrested the outbreak. Experimenters should be cautious in ascribing toxicity to a test article based solely on increased hepatic enzyme activity associated with chronic periportal inflammation.     

Modeling depression in adult female cynomolgus monkeys (Macaca fascicularis)

Depressive disorders are prevalent, costly, and poorly understood. Male rodents in stress paradigms are most commonly used as animal models, despite the two-fold increased prevalence of depression in women and sex differences in response to stress. Although these models have provided valuable insights, new models are needed to move the field forward. Social stress-associated behavioral depression in adult female cynomolgus macaques closely resembles human depression in physiological, neurobiological, and behavioral characteristics, including reduced body mass, hypothalamic-pituitary-adrenal axis perturbations, autonomic dysfunction, increased cardiovascular disease risk, reduced hippocampal volume, altered serotonergic function, decreased activity levels, and increased mortality. In addition, behaviorally depressed monkeys also have low ovarian steroid concentrations, even though they continue to have menstrual cycles. Although this type of ovarian dysfunction has not been reported in depressed women and is difficult to identify, it may be the key to understanding the high prevalence of depression in women. Depressive behavior in female cynomolgus monkeys is naturally occurring and not induced by experimental manipulation. Different social environmental challenges, including isolation vs. subordination, may elicit the depression-like response in some animals and not others. Similarly, social subordination is stressful and depressive behavior is more common in socially subordinate monkeys. Yet, not all subordinates exhibit behavioral depression, suggesting individual differences in sensitivity to specific environmental stressors and enhanced risk of behavioral depression in some individuals. The behavior and neurobiology of subordinates is distinctly different than that of behaviorally depressed monkeys, which affords the opportunity to differentiate between stressed and depressed states. Thus, behaviorally depressed monkeys exhibit numerous physiological, neurobiological, and behavioral characteristics same as those of depressed human beings. The nonhuman primate model represents a new animal model of depression with great promise for furthering our understanding of this prevalent and debilitating disease and identifying novel therapeutic targets.     

Ratio of leptin to adiponectin as an obesity index of cynomolgus monkeys (Macaca fascicularis).

Obesity is responsible for inducing various metabolic diseases. Laboratory-bred cynomolgus monkeys exhibit spontaneous onset of obesity. However, to date, no blood chemistry index to identify the state of obesity in cynomolgus monkeys has been determined. In the present study, to determine such an index, we measured the serum levels of two adipocyte-derived hormones, leptin and adiponectin, and evaluated the relationship between these hormones and other serum energy metabolic factors (i.e. insulin, total protein, glucose, total cholesterol and triglyceride) as well as the percentage of body fat (%Fat) in mature cynomolgus monkeys. Both in females and males, leptin was positively correlated with insulin and %Fat, and adiponectin was negatively correlated with insulin and %Fat. In female cynomolgus monkeys, leptin, adiponectin, and glucose were selected as the most important determinants for %Fat in multiple regression analysis, and in male cynomolgus monkeys, leptin was selected. The ratio of leptin to adiponectin (L/A ratio) was significantly elevated in the animals with %Fat over 40 (P < 0.01). The results indicate that L/A ratio is a potential index for comprehensively identifying obesity in cynomolgus monkeys.     

Deep-breath frequency in bronchoconstricted monkeys (Macaca fascicularis).

Deep-breath frequency has been shown to increase in spontaneously obstructed asthmatic subjects. Furthermore, deep breaths are known to be regulated by lung rapidly adapting receptors, yet the mechanism by which these receptors are stimulated is unclear. This study tested the hypothesis that deep-breath frequency increases during experimentally induced bronchoconstriction, and the magnitude of the increased deep-breath frequency is dependent on the method by which bronchoconstriction is induced. Nine cynomolgus monkeys (Macaca fascicularis) were challenged with methacholine (MCh), Ascaris suum (AS), histamine, or an external mechanical resistance. Baseline (BL) and challenge deep-breath frequency were calculated from the number of deep breaths per trial period. Airway resistance (Raw) and tissue compliance (Cti), as well as tidal volume, respiratory rate, and minute ventilation, were analyzed for BL and challenged conditions. Transfer impedance measurements were fit with the DuBois model to determine the respiratory parameters (Raw and Cti). The flow at the airway opening was measured and analyzed on a breath-by-breath basis to obtain the ventilatory parameters (tidal volume, respiratory rate, and minute ventilation). Deep-breath frequency resulting from AS and histamine challenges [0.370 (SD 0.186) and 0.467 breaths/min (SD 0.216), respectively] was significantly increased compared with BL, MCh, or external resistance challenges [0.61 (SD 0.046), 0.156 (SD 0.173), and 0.117 breaths/min (SD 0.082), respectively]. MCh and external resistance challenges resulted in insignificant changes in deep-breath frequency compared with BL. All four modalities produced similar levels of bronchoconstriction, as assessed through changes in Raw and Cti, and had similar effects on the ventilatory parameters except that non-deep-breath tidal volume was decreased in AS and histamine. We propose that increased deep-breath frequency during AS and histamine challenge is the result of increased vascular permeability, which acts to increase rapidly adapting receptor activity.     

Pregnancy-induced sclerosis in the myometrial vessels of cynomolgus monkeys (Macaca fascicularis)

Sclerotic changes were found histologically in the myometrial vessels of 27 out of 33 cynomolgus monkeys (Macaca fascicularis). The sclerosis was composed of fibrous proliferations and intimal thickening. These changes were not observed in nulliparous cases, but were found only in multiparous ones. The findings suggest that the sclerotic changes in the myometrial vessels of cynomolgus monkeys are a pregnancy-induced phenomenon.     

Yersiniosis in a breeding unit of Macaca fascicularis (cynomolgus monkeys)

2 outbreaks of acute fatal enteric disease involving 20 animals in a breeding unit of approximately 200 cynomolgus monkeys were diagnosed as yersiniosis; Yersinia pseudotuberculosis was isolated from 50% of the clinically affected animals. Post-mortem findings included enlarged mesenteric lymph nodes with some enterocolitis and necrotic foci in liver and spleen. Approximately 7% of clinically healthy monkeys were found to be excreting Y. pseudotuberculosis and a further 5% Y. enterocolitica. Rectal swabs, though less convenient, were better than faecal samples for the detection of Yersinia spp. in 'healthy' monkeys. Efficiency of the cold saline technique and direct plating for isolating Yersinia spp. were compared. It is thought likely that the infection was introduced into the unit by asymptomatic infected monkeys.