Pulmonary responsiveness to methacholine and disodium hexachloroplatinate (Na2PtCl6) aerosols in cynomolgus monkeys (Macaca fascicularis)

Hyperreactivity of the airways is a common finding in human asthma, and responsiveness to inhaled methacholine aerosols is routinely used for assessing airway irritability. Workers in precious metal refineries demonstrate pulmonary signs suggestive of asthma, presumably related to exposure to soluble platinum salts. In these workers, evidence of physiologic dysfunction precedes immunologic evidence (skin test) of disease, suggesting an initial pharmacologic mechanism. With a primate animal model for the screening of occupational asthmogens, 24 Cynomolgus monkeys were evaluated for their comparative pulmonary responsiveness to inhaled aerosols of methacholine and sodium hexachloroplatinate (Na2PtCl6). Average pulmonary flow resistance (RL), dynamic compliance (CLdyn), maximum expiratory flow volume (MEFV), and respiratory frequency changes were evaluated after bronchoprovocation challenge. Both agents produced dose-dependent increases in RL, dose-dependent decreases in CLdyn and MEFV, and no effect on respiratory rates. Analyses of the correlation between concentration effects of the two agents showed no association between cholinergic airway irritability status and Na2PtCl6-induced bronchoconstriction. Na2PtCl6 bronchoprovocation produced significantly greater flow impairment at lower lung volumes when compared to methacholine concentrations with equipotent effects on RL and CLdyn. These compounds have differential effects on peripheral airway function. The lack of respiratory rate change seen on bronchoprovocation with these compounds, in comparison to the rapid shallow breathing in anesthetized monkeys following irritant or histamine challenge, indicates that neither aerosol stimulated pulmonary irritant receptors.     

Evaluation of the onset and duration of response to cold air inhalation challenge in cynomolgus monkeys (Macaca fascicularis)

Cold air inhalation challenge (CAIC) for the evaluation of bronchial reactivity has been proposed as a physical agent alternative to chemical agent challenges (methacholine or histamine), especially suitable for the occupational environment. The present investigation describes and evaluates a method for performing cold air inhalation challenge in Cynomolgus monkeys (Macaca fascicularis), a species shown to be useful in animal modeling studies of occupational asthma. Six adult male anesthetized monkeys were ventilated by changes in external pressure while breathing cold air (-25 degrees C to -30 degrees C). Pulmonary function testing was performed at 10, 25, 40 and 55 min post-challenge. Significant increases (P less than 0.05) in average pulmonary flow resistance (RL) and decreases in dynamic compliance (CL dyn) were observed, with maximum impairment occurring at 25 min post-challenge, with a trend towards a return to baseline values at 55 min post-challenge. Peak expiratory flow rate (PEFR), forced expiratory volume in 0.5 s/forced vital capacity (FEV0.5/FVC) and forced expiratory flow at 50% forced vital capacity (FEF50) showed the same general pattern of reduction as seen with RL; however, these results were not statistically significant, most probably owing to individual monkey variability and the small number of monkeys (N = 6) used. A repeat challenge at 25 min after a primary challenge yielded increased RL in one monkey, suggesting that no absolute refractory period is present from CAIC. Results of these studies demonstrate that CAIC causes bronchoconstriction in monkeys and may be useful in further animal modeling studies designed to determine the asthmogenic/airway irritant potential of occupational toxicants.     

Toxicological consequences of feeding PCB congeners to infant rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) monkeys.

In a study designed to minimize interspecies extrapolation of toxicological data, nine rhesus (Macaca mulatta) and 15 cynomolgus (M. fascicularis) day-old infant monkeys were separated from their dams following parturition and hand-reared using a liquid non-human primate formulation. The infants were randomly divided into a control and a treated group which received a mixture of polychlorinated biphenyl (PCB) congeners analogous to those found in breast milk from Canadian women. The concentration of congeners in the dosing media resulted in each infant receiving a total of 7.5 microg PCB congeners/kg body weight/day. The congeners were added either to the liquid formulation or to corn oil and administered to the back of the monkey's mouth for 20 weeks. Monthly blood and adipose specimens were obtained during the dosing period and then periodically until the monkey was necropsied or taken off test (minimum of 66 weeks on test) for congener analysis. Parameters such as body weight, formula consumption, tooth eruption, somatic measurements, haematology and serum biochemistry were monitored throughout the study. In addition, a qualitative evaluation of the absorption and depletion of the various congeners was undertaken as was an immunological evaluation. For the monitored parameters, very few differences were found to be statistically significant. For the immunological parameters, the only statistically differences found were a reduction over time for immunoglobulins M and G antibodies to sheep red blood cells (cyno, P = 0.025; rhesus, P = 0.002) and a treatment-related reduction in the levels of the HLA-DR cell surface marker (mean percent, P = 0.016; absolute levels, P = 0.027). There were some qualitative differences regarding absorption and depletion rates for the various congeners, but it could not be definitely ascertained whether these differences were due to species differences or dosing mode. However, statistically significant differences were found for treatment (P = 0.0293) as well as for species and vehicle regarding the concentration of PCB in blood (species;--P = 0.0399; treatment--P = 0.0001) and adipose tissue (species--P = 0.0489; treatment--P = 0.0001).     

Effects of toxaphene on the immune system of cynomolgus (Macaca fascicularis) monkeys.

Toxaphene, dissolved in glycerol/corn oil, was administered at 0.1, 0.4 or 0.8 mg/kg body weight/day in gelatin capsules to groups of 10 young adult female cynomolgus monkeys (Macaca fascicularis), while a group of five male monkeys (Macaca fascicularis) received 0.8 mg/kg body weight/day. Control male (a group of five) and female (a group of 10) monkeys ingested the glycerol/corn oil vehicle only. Treatment continued for 75 weeks. Testing for immune effects was initiated at 33 weeks of treatment. Immunization was initiated at 44 weeks of treatment. Pairwise comparisons between each of the treated female groups to the control indicated that the mean primary (post-immunization weeks 1-4) and secondary (post-immunization weeks 5-8) anti-SRBC IgM responses were significantly reduced at the 0.4 and 0.8 mg/kg body weight/day doses compared to the control (P< or =0.05). The mean primary (post-immunization weeks 1-4) anti-SRBC IgG response was significantly reduced compared to the control (P< or =0.05), while the secondary (post-immunization weeks 5-8) anti-SRBC IgG was not significantly affected by treatment (P>0.05). The mean anti-tetanus toxoid IgG response in the 0.8 mg/kg body weight/day dose group The mean primary anti-SRBC (IgM) response in the treated males was significantly different from the control (P<0.05), while the primary anti-SRBC IgG response was not affected by treatment. The mean absolute B-lymphocyte numbers in the female group administered 0.8 mg/kg of toxaphene was significantly reduced compared to the control (P< or =0.05). All other parameters including the natural killer cell activity, the delayed-type hypersensitivity response, the lymphoproliferative response of peripheral blood leukocytes to the mitogens Con A and PWM and the serum cortisol levels were not affected significantly by treatment (P>0.05). The no-observed-adverse-effect level (NOAEL) for the female monkeys based on the toxaphene effects on humoral immunity was 0.1 mg/kg body weight/day.     

Diurnal pituitary-adrenal activity during schedule-induced polydipsia of water and ethanol in cynomolgus monkeys (Macaca fascicularis)

Rationale

Intermittent delivery of an important commodity (e.g., food pellets) generates excessive behaviors as an adjunct to the schedule of reinforcement (adjunctive behaviors) that are hypothesized to be due to conflict between engaging and escaping a situation where reinforcement is delivered, but at suboptimal rates.

Objectives

This study characterized the endocrine correlates during schedule-induced polydipsia of water and ethanol using a longitudinal approach in non-human primates.

Methods

Plasma adrenocorticotropic hormone (ACTH) and cortisol were measured in samples from awake cynomolgus monkeys (Macaca fascicularis, 11 adult males) obtained at the onset, mid-day, and offset of their 12-h light cycle. The monkeys were induced to drink water and ethanol (4 %?w/v, in water) using a fixed time (FT) 300-s interval schedule of pellet delivery. The induction fluid changed every 30 sessions in the following order: water, 0.5 g/kg ethanol, 1.0 g/kg ethanol, and 1.5 g/kg ethanol. Following induction, ethanol and water were concurrently available for 22 h/day.

Results

The FT 300-s schedule gradually increased ACTH, but not cortisol, during water induction to a plateau sustained throughout ethanol induction in every monkey. Upon termination of the schedule, ACTH decreased to baseline and cortisol below baseline. Diurnal ACTH and cortisol were unrelated to the dose of ethanol, but ACTH rhythm flattened at 0.5 g/kg/day and remained flattened.

Conclusions

The coincidence of elevated ACTH with the initial experience of drinking to intoxication may have altered the mechanisms involved in the transition to heavy drinking.     

Developmental toxicity assessment of tanezumab,an anti-nerve growth factor monoclonal antibody,in cynomolgus monkeys (Macaca fascicularis)

Two intravenous studies with tanezumab, an anti-nerve growth factor monoclonal antibody, were conducted in pregnant cynomolgus monkeys to assess potential effects on pregnancy and pre- and postnatal development. Study 1 evaluated infants up to 12 months of age following weekly maternal dosing (0, 0.5, 4 or 30 mg/kg; 18 per group) from gestation day (GD) 20 through parturition. Study 2 evaluated infants 2 months postnatally following weekly maternal dosing (0, 0.5 or 30 mg/kg; 20–21 per group) from GD 20 through 48. In the absence of maternal toxicity, tanezumab increased stillbirth and post-birth infant mortality/morbidity, decreased infant growth and resulted in microscopic changes in the peripheral sympathetic and sensory nervous system of the infants at all doses. Decreased primary antibody responses and increased incidences in skin changes in infants were also observed. The no-observed-adverse-effect-level for maternal toxicity was 30 mg/kg and <0.5 mg/kg for developmental toxicity.     

Central nervous system monoamine correlates of social dominance in cynomolgus monkeys (Macaca fascicularis).

Social dominance is a fundamental component of both human and nonhuman primate sociality. However, its neurobiological correlates remain incompletely understood. We evaluated the association between dominance status and monoamine metabolite concentrations in cisternal cerebrospinal fluid (CSF) in adult male (n = 25) and female (n = 21) cynomolgus macaques (Macaca fascicularis) housed in unisexual social groups. Concentrations of the metabolites of dopamine (homovanillic acid [HVA]), norepinephrine (3-methoxy-4-hydroxyphenylglycol [MHPG]) and serotonin (5-hydroxyindoleacetic acid [5-HIAA]) were assayed. Dominant monkeys, both males and females, had significantly higher CSF HVA concentrations than did subordinates (p values <.05). Among males, but not females, dominants also had lower CSF 5-HIAA than subordinates (p <.05). The Dominance-HVA association observed here is consistent with recent speculation that social extraversion, a dominance-related personality trait in humans, may also reflect heightened central nervous system dopaminergic activity.     

Structure-dependent induction of CYP1A by polychlorinated biphenyls in hepatocytes of cynomolgus monkeys (Macaca fascicularis)

Until now structure-activity relationships (SARs) for in vitro or in vivo CYP1A induction by polychlorinated biphenyls (PCBs) have only been determined in rodents and birds. This study describes the first development of such a SAR in a primate species by using hepatocyte cultures of cynomolgus monkey (Macaca fascicularis). Hepatocyte cultures of primate species might be a more suitable model for humans than those of rodents. For 20 PCBs, the in vitro induction of CYP1A activity was determined by measuring dealkylation of either methoxyresorufin or ethoxyresorufin. Selection of PCBs was based on multivariate physical-chemical characterization of all tetra- through heptachlorinated congeners. The non-ortho-substituted congeners were found to be the most potent inducers, followed by the mono-ortho-substituted PCBs. Multiple-ortho-substituted congeners, with more than five chlorine atoms, were inducers of CYP1A activity in monkey hepatocytes as well, with EC50 values approximately 10,000 times higher than 3,3',4,4',5 PeCB (PCB 126), the most potent congener. Using partial least-squares (PLS) modeling, predictions of CYP1A activity were established for all other tetra- to hepta-substituted congeners. Several congeners, which are abundant in the (a)biotic environment, were predicted to have CYP1A activity in cynomolgus monkey hepatocytes. Because induction of CYP1A activity is generally used as an early and sensitive biomarker for the Ah-receptor-mediated potential of a chemical, further studies are recommended to determine the possible risks of these multiple-ortho PCBs to humans.     

Experimental oral toxicity of domoic acid in cynomolgus monkeys (Macaca fascicularis) and rats. Preliminary investigations

A recent outbreak of marine food poisoning in humans was attributed to the consumption of blue mussels (Mytilus edulis L.) contaminated with domoic acid (DA) that was produced by the diatom Nitzschia pungens. The clinical and morphological effects of single oral doses of extracts of mussels contaminated with DA or of DA isolated from toxic mussels were investigated in small groups (one to six) of cynomolgus monkeys (Macaca fascicularis; 0.5-10 mg DA/kg body weight) and of Sprague-Dawley rats (60 to 80 mg DA/kg body weight). Control animals were either given saline or were not treated. To test whether monosodium glutamate, present in the food consumed by some affected humans, and dimethylsulphoxide, suspected of being present in the plankton, enhanced the response, monosodium glutamate (at 0.25% of mussel extract bolus) or dimethylsulphoxide (at 1 g per bolus) were co-administered to two (one each) of the DA-treated monkeys. DA-treated monkeys developed transient excitation characterized by vomiting. DA-treated rats showed withdrawal followed by hyperexcitation and death (in one case). Mild to moderate central nervous system lesions consistent with neuroexcitation were present in both monkeys and rats. The addition of monosodium glutamate and dimethylsulphoxide had no significant effect on the appearance and severity of central nervous system clinical signs and lesions. The wide variations in the response of test animals to orally administered DA were attributed to the protective effect of vomiting, and to suspected incomplete or slow gastro-intestinal absorption of the toxic agent. The results reinforce the view that DA is an emetic and that under appropriate conditions may also inflict excitotoxic central nervous system damage.     

Toxicity of 8-methoxypsoralen in cynomolgous monkeys (Macaca fascicularis)

Male and female cynomolgous monkeys were administered 0, 2, 6 or 18 mg/kg 8-methoxypsoralen (8-MOP) 3 times a week orally for 26 consecutive weeks. Dose-dependent emesis was the most sensitive indicator of 8-MOP toxicity. The lowest dose to elicit emesis was 3 x 6 mg/kg/week of 8-MOP. Among the histological findings proliferation of Kupffer cells was the only recurring observation. However, these finding as well as some hematological and serum electrolyte changes lacked a dose-response relationship. In the highest dosage group one female monkey was found in moribund condition on the 39th day of the study and was killed. Histopathological evidence indicated beginning shock as the cause of the rapidly deteriorating health of the monkey. Similar to effects in man and rats, 8-MOP displayed nonlinear pharmacokinetics in the cynomolgous monkey, saturation occurring between 3 x 2 and 3 x 6 mg/kg/week. Increased clearance of 8-MOP in the lowest dosage group after 26 test weeks was attributed to a combination of enzyme induction and saturable first pass effect. Since the plasma profile of 8-MOP at the lowest dose (3 x 2 mg/kg/week) in cynomolgous monkeys closely resembles that in humans after therapeutic doses (0.4-0.6 mg/kg) and because of other similarities (vomiting as earliest sign of toxicity, saturable first pass effect), it is reasonable to assume that chronic toxicity of 8-MOP as defined in this study is quite predictive for man.     

Effects of toxaphene on the immune system of cynomolgus (Macaca fascicularis) monkeys. A pilot study.

Toxaphene in glycerol/corn oil was administered at 1mg/kg body weight/day, 7 days/week in gelatin capsules to four healthy young adult cynomolgus (Macaca fascicularis) (two male and two female) monkeys for 52 weeks. Control monkeys ingested glycerol/corn oil only. Testing for immune effects was initiated at 34 weeks of treatment. Results included: reduced anti-sheep red blood cell (SRBC) titres for immunoglobulins (Ig) M and G; increased IgG titres to pneumococcal antigens, but not to the tetanus toxoid antigen; reduced T-helper/inducer mean lymphocyte numbers and the mean T-helper/inducer:T-suppressor/cytotoxic cell ratio and reduced respiratory burst activity in peripheral blood monocytes and granulocytes, albeit no changes on the phagocytic activity of these cells were detected. The above noted effects although not statistically significant (P0.05) suggest that chronic exposure to low levels of toxaphene may be immunosuppressive in cynomolgus monkeys and may pose a hazard to human health. To advance our understanding of the degree of hazard that toxaphene may pose to human health, we have undertaken additional chronic studies with a larger number of animals. Particular attention is focused on determining the potential immunotoxic effects of toxaphene in offspring following in utero exposure.     

Toxicological consequences of toxaphene ingestion by cynomolgus (Macaca fascicularis) monkeys. Part 1: pre-mating phase.

A total of 40 menstruating cynomolgus monkeys (Macaca fascicularis) with an average age of 7.25 +/- 1.06 years (standard deviation), five male cynomolgus monkeys with an average age of 12.6 +/- 0.66 years, and five male cynomolgus males with an average age of 6.2 +/- 0.23 years were obtained from the Health Canada breeding laboratory. The females were initially randomized to the four test groups in accordance with their previous reproductive success and body weight. They were then randomly allocated between two similar environmentally-controlled rooms (20 females/room). The males were randomly assigned to one of the test rooms (six or four males/room). The female test groups self-ingested capsules containing doses of 0, 0.1, 0.4 or 0.8 mg (Groups A, B, C, D) of technical grade toxaphene/kg body weight/day (i.e. five females/dose group/room). The older males (Group E) were proven breeders and were used exclusively for mating and their capsules contained no toxaphene. The younger males (Group F) ingested capsules containing 0.8 mg of technical grade toxaphene/kg body weight/day. After 20 weeks of daily dosing, it was assumed, based on the results of a pilot study [Andrews P., Headrick K., Pilon J.-C., Bryce F., Iverson F. (1996) Capillary GC-ECD and ECNI GCMS characterization of toxaphene residues in primate tissues during a feed study. Chemosphere 32, 1043-1053], that the treated monkeys had attained a qualitative pharmacokinetic steady state regarding the concentration of toxaphene in their adipose tissue and blood. On a daily basis, each monkey's feed and water consumption as well as its health were monitored. In addition, the females were swabbed daily to determine menstrual status. On a weekly basis, each monkey's body weight was determined and its dose of toxaphene adjusted. Detailed clinical examinations were conducted at intervals of 4 weeks or less. Periodically, starting prior to the initiation of dosing, blood samples were taken for serum biochemistry, haematology and toxaphene analysis. In addition, specimens from the nuchal fat pad were also obtained for toxaphene analysis. Statistical analysis did not reveal any effect of treatment on body weight gain, feed consumption, water consumption or haematological parameters during the 75-week pre-mating phase. The only serum biochemistry parameter which was consistently affected by treatment was cholesterol, the level of which decreased in a linear fashion as a consequence of dose, and this effect increased with time on test (P = 0.037). No other biological effects of toxaphene ingestion were found during the premating phase of this toxicological-reproduction study.     

Chronic maternal methanol inhalation in nonhuman primates (Macaca fascicularis): exposure and toxicokinetics prior to and during pregnancy

Toxicokinetic studies were conducted following daily inhalation exposure to methanol vapor prior to and throughout pregnancy in adult female Macaca fascicularis monkeys. They were part of a larger study to investigate the effects of chronic methanol exposure on maternal reproductive performance and early offspring effects. In a two-cohort study design, 48 females (24/cohort) were assigned to parallel exposure groups at 0 (control), 200, 600, or 1800 ppm methanol vapor for approximately 2.5 h/day, 7 days/week throughout breeding and pregnancy. Blood methanol at 30 min postexposure was monitored biweekly. The time course for the clearance of blood MeOH concentrations following exposure was characterized on four occasions: twice during the prebreeding period and during mid- and late pregnancy. Average blood methanol concentrations at 30 min postexposure were 5, 11, and 35 microg/ml across all four toxicokinetic studies in the 200, 600 and 1800 ppm groups, respectively. Blood concentrations in the 200 ppm group were barely above basal (preexposure) blood methanol concentrations or those observed in the control group (approximately 3 microg/ml). Nonlinear elimination kinetics were observed in most of the 1800 ppm group females. There was a decrease in elimination half-life (7-20%) and an increase in clearance (30%) after 3-months of daily MeOH exposure compared to the initial exposure. There were no statistically significant changes in the first-order blood methanol half-life or clearance during pregnancy, but the mean distribution volume per kilogram body weight decreased by 22% and 17% in the 600 and 1800 ppm groups. Plasma formate levels did not differ between the methanol and control exposure groups. Plasma formate and serum folate concentrations increased slightly over the course of this study in both the exposed and control groups but these increases were not related to methanol exposure.     

Characterization of CYP1A in hepatocytes of cynomolgus monkeys (Macaca fascicularis) and induction by different substituted polychlorinated biphenyls (PCBs)

Cynomolgus monkeys (Macaca fascicularis) have been used previously as a model to study effects on cytochrome P450 (CYP) regulation. Until now it has not been elucidated which CYP1A proteins are present in this primate species. The aim of this study was to characterize CYP1A in untreated hepatocytes of cynomolgus monkey using two specific CYP1A inhibitors (α -naphthoflavone and furafylline). The effect of different substituted polychlorinated biphenyls (PCBs) on CYP1A regulation was also studied in these hepatocytes. Small quantities of CYP1A2 have been identified in untreated hepatocytes. Northern blots showed the presence of a CYP1A mRNA in untreated hepatocytes, when hybridizations where performed with human CYP1A2 cDNA. Inhibitions with furafylline and α -naphthoflavone also suggested the presence of CYP1A2 properties. After induction with different PCBs, (probably) CYP1A1 mRNA and enzyme activity were induced in cynomolgus monkey hepatocytes. As expected, 2,3′,4,4′,5-PeCB (PCB no. 118), a mono-ortho substituted congener, was a potent CYP1A inducer but 2,2′,3,4,4′,5′,5′-HpCB (PCB no. 180), a di-ortho and 2,2′,3,4′,5,5′,6-HpCB (PCB no. 187), a tri-ortho substituted PCB, could induce CYP1A mRNA and enzyme activity in cynomolgus monkey hepatocytes as well. Received: 20 April 1998 / Accepted: 1 July 1998     

Ten-day repeated-exposure inhalation study of dimethylformamide (DMF) in cynomolgus monkeys.

Cynomolgus monkeys showed no measurable adverse effects following inhalation of 500 ppm dimethylformamide (DMF), 6 h/d, 5 d/wk, for 2 weeks either when exposed whole-body or head-only (one monkey per exposure route). Measurement of DMF concentrations into and out of the head-only exposure unit along with measurement of the tidal volume suggest that DMF absorption by the respiratory tract is approximately 100% at a concentration of 500 ppm. Plasma samples taken 1/2 to 18 h after the first exposure show DMF AUC values which were 3 times higher in the monkey exposed by whole-body, indicating considerable absorption by non-inhalation route(s). The same comparison of plasma samples taken following the final (10th) exposure similarly had a 6-times DMF AUC value for the monkey exposed by whole-body. From this study it is apparent that the practice of avoiding dermal contact with DMF is important in reducing the likelihood of producing DMF-induced injury in the workplace.     

Discriminative stimulus effects of ethanol and 3α-hydroxy-5α-pregnan-20-one in relation to menstrual cycle phase in cynomolgus monkeys (Macaca fascicularis)

 The present study was designed to characterize the discriminative stimulus effects of ethanol and the neurosteroid 3α-hydroxy-5α-pregnan-20-one (allopregnanolone) in nonhuman primates as a function of menstrual cycle phase. Female cynomolgus monkeys (Macaca fascicularis) were trained in a two-lever procedure to discriminate 1.0 g/kg ethanol (IG, 30 min pretreatment) from water using food reinforcement. A cumulative dosing procedure was used to assess changes in the potency of ethanol and an endogenous anxiolytic steroid in the follicular versus the luteal phase of the menstrual cycle. Plasma progesterone and allopregnanolone levels were determined within 24 h of testing to verify phase of menstrual cycle. The monkeys were more sensitive to the discriminative stimulus effects of ethanol and the ethanol-like effects of the endogenous neuroactive steroid allopregnanolone during the luteal phase of the menstrual cycle. These findings suggest that changes in the endogenous levels of ovarian-derived progesterone and allopregnanolone alter sensitivity to the discriminative stimulus effects of ethanol. Received: 13 March 1996 / Final version: 26 September 1996     

Effects elicited by toxaphene in the cynomolgus monkey (Macaca fascicularis): a pilot study.

Toxaphene, which was added to glycerol/corn oil, was administered at a level of 1 mg/kg body weight/day in gelatin capsules to four healthy young adult cynomolgus (Macaca fascicularis) monkeys for 52 weeks. Four control monkeys ingested capsules containing only glycerol/corn oil. Each group had two males and two females. On a daily basis, each monkey's feed and water consumption was determined, its health was monitored and the females were swabbed to evaluate menstrual status. On a weekly basis, each monkey's body weight was determined and a detailed clinical evaluation was performed. At 4-week intervals, blood samples were taken for serum biochemistry, haematology and toxaphene analysis. Also, a local anaesthetic was administered to the nuchal fat pad area of each monkey, and adipose samples were obtained for toxaphene analysis. 1 day prior to the biopsies, a 24-h urine and faecal collection was obtained for toxaphene analysis. After 34 weeks of treatment, the immune system of the monkeys was evaluated. After 52 weeks of dosing, all treated and two control animals were necropsied. Liver samples were obtained and microsomal fractions were prepared immediately. A portion of liver and kidney was taken for toxaphene analysis. All of the major internal organs were weighed and bone marrow evaluations were conducted. Organ and tissue samples were fixed in 10% formalin and processed for light microscopy. There was no effect of treatment on body weight gain, feed consumption, water consumption or haematological parameters. Two major clinical findings were inflammation and/or enlargement of the tarsal gland and impacted diverticulae in the upper and lower eye lids. At necropsy, the relative spleen and thymus weights were greater for the treated monkeys than the controls. Toxaphene administration produced an increase in metabolism of aminopyrene, methoxyresorufin and ethoxyresorufin, three substrates that are altered specifically by cytochrome P450-based hepatic monooxygenase enzymes. Histopathological examination of tissues was unremarkable by light microscopy. Tissue analysis for toxaphene and immunology findings have been published elsewhere.     

The influence of social structure on social isolation in amphetamine-treated Java monkeys (Macaca fascicularis)

Amphetamine-induced social isolation in monkeys has often been considered a valid animal model for certain negative symptoms of schizophrenia. However, there appear to be many ambiguities in relation to the exact nature of the isolation. Therefore, the effect of orally administered amphetamine (AMP) on the occurrence of social isolation in Java monkeys was studied. In part I the rank dependency of the effects of AMP (0.5mg/kg) was investigated in four alpha-males and three beta-males. AMP increased 'proximity' and 'passive groom', and decreased 'active allogroom' in alpha-males. In contrast, AMP decreased all three behavioural elements to a certain extent in beta-males. It is concluded that AMP induces social isolation in beta-males, but not in alpha-males. In part II of this study the AMP-induced behaviour of the treated monkey and the simultaneously occurring changes in the non-treated monkeys were investigated in a detailed study of a single social group. AMP significantly reduced the frequency of 'exploration', 'locomotion', 'self-groom', 'swing', 'active groom', 'inspect', 'approach' and originally-present stereotypies. Thus AMP apparently reduces the ability to initiate behaviour which is characteristic for the adult animal. AMP did not affect the frequency of 'present' and 'play' and enhanced that of 'aggression' and 'fear' in the beta-male; it also elicited various juvenile-like behaviours in both alpha- and beta-males, suggesting that AMP induces a behavioural regression. Furthermore, the behaviour of the non-treated monkeys of the group was decisive for the occurrence of social isolation of the treated monkey. Thus, the effects of AMP on the social behaviour of Java monkeys depend on the individual sensitivity, the social position which the subject occupies in its group, and the behaviour of the partners of the treated subject.     

Antagonism of TCDD-induced ethoxyresorufin-O-deethylation activity by polybrominated diphenyl ethers (PBDEs) in primary cynomolgus monkey (Macaca fascicularis) hepatocytes

Polybrominated diphenyl ethers (PBDEs) are widespread environmental pollutants, and the levels of certain congeners have been increasing in biota and abiota in recent decades. Some PBDEs are lipophilic and persistent, resulting in bioaccumulation in the environment. Their structural similarity to other polyhalogenated aromatic hydrocarbons (PHAHs) such as polychlorinated biphenyls (PCBs) has raised concerns that PBDEs might act as agonists for the aryl hydrocarbon receptor (AhR). Recent studies in our laboratory with human and rat cell lines indicated no AhR mediated CYP1A1 induction for PBDEs. However, an earlier in vitro study by Van der Burght et al. (1999) [Van der Burght, A.S., Clijsters, P.J., Horbach, G.J., Andersson, P.L., Tysklind, M., van den Berg, M., 1999. Structure-dependent induction of CYP1A by polychlorinated biphenyls in hepatocytes of cynomolgus monkeys (Macaca fascicularis). Toxicol. Appl. Pharmacol. 155, 13-23] indicated that in cynomolgus monkey (M. fascicularis) hepatocytes PCBs with a non-planar configuration could induce CYP1A. As PBDEs show a structural similarity with non-planar (ortho substituted) PCBs, our present study focused on the possible CYP1A induction by PBDEs (BDE-47, -99, -100, -153, -154, -183, and -77) in individual preparations (n=4) of primary hepatocytes of cynomolgus monkeys (M. fascicularis). 7-Ethoxyresorufin-O-deethylase (EROD) was used as a marker for CYP1A-mediated catalytic activity. Cells were exposed for 48 h to various PBDE concentrations (0.01-10 microM), positive controls 2,3,7,8-TCDD (0.001-2.5 nM) and PCB-126 (0.01-10nM), and negative control (DMSO vehicle alone). No statistically significant induction of CYP1A was observed in the hepatocytes after 48 h of exposure to all environmentally relevant PBDEs. After exposing hepatocytes to PBDEs in combination with TCDD, a concentration-dependent decrease in TCDD-induced EROD activity was observed. All PBDEs tested showed a similar reduction in each of four experiments, though quantitative differences were observed. The observed antagonism of TCDD-induced EROD activity by PBDEs occurred in both male (n=3) and female (n=1) hepatocytes and was not due to catalytic inhibition of EROD activity or cytotoxicity. However, based on the results of this study we do not expect these antagonistic effects of PBDEs on CYP1A induction at environmental relevant levels, since these in vitro interactive effects with TCDD were observed only at relatively high concentrations that are normally not seen, e.g. in the human body.