Behavioural responses to diazepam of drug-naive and experienced monkeys (Macaca mulatta)

Effects of 5 mg/kg diazepam given once a week for several weeks to drug-naive and drug-experienced monkeys were studied on a spatial delayed-alternation task. In both groups response latency was increased and the number of correct responses was reduced. The effects were consistent over weeks in the experienced monkeys, but in the naive monkeys there were greater initial effects on response latency and on repeat errors, and these lessened over 2–3 weeks. Thereafter, effects resembled those observed in the experienced group. Results are discussed in terms of the possible factors involved in the development and persistence of tolerance to benzodiazepines.     

Flurazepam hydrochloride and its principal metabolites: Behavioural studies in the monkey (Macaca mulatta)

Effects of flurazepam and its two principal metabolites, hydroxyethylflurazepam and desalkylflurazepam (0.5, 1.0, 3.0 and 10.0 mg/kg), were studied on a delayed differentiation task in the monkey. Flurazepam (10.0 mg/kg) and hydroxyethylflurazepam (3.0 and 10.0 mg/kg) decreased the number of correct responses and increased response latency; effects persisted to 4 h with the highest dose. Marked impairment of performance was observed with all doses of desalkylflurazepam and effects of 3.0 and 10.0 mg/kg persisted to 24 h. Evidence of a disinhibitory effect of desalkylflurazepam was demonstrated. The study would point to a consideration of both metabolites in the hypnotic effect and in the impairment of performance observed after acute ingestion of flurazepam in man.     

Behavioural and pharmacokinetic studies in the monkey (Macaca mulatta) with diazepam, nordiazepam and related 1,4-benzodiazepines.

1. Behavioural activity (delayed differentiation and spatial delayed alternation) and pharmacokinetics of diazepam and its metabolites, N-desmethyldiazepam (nordiazepam), 3-hydroxydiazepam (temazepam) and 3-hydroxy-N-desmethyldiazepam (oxazepam), and of dipotassium clorazepate (clorazepate), were studied in the monkey (Macaca mulatta). Diazepam and its metabolites (1.8 and 3.0 mg/kg) and clorazepate (2.6 and 4.3 mg/kg) were given by intraperitoneal injection. 2. Hydroxylation of diazepam (temazepam and oxazepam) led to a loss of, or a considerable reduction in, behavioural activity, whereas activity was preserved, though modified, by demethylation (nordiazepam). It was not possible to establish change in behaviour at specific time intervals after clorazepate, but combined performance data revealed an effect. 3. The maximum mean plasma concentrations of diazepam, temazepam, oxazepam and clorazepate were observed at 0.5 h, and the maximum mean plasma concentration of nordiazepam was observed at 1 hour. Plasma concentrations of nordiazepam were the highest and decreased monoexponentially. Plasma concenqrations of the other drugs declined rapidly at first but more slowly later, and these data were analysed as biexponential models. In the analysis for metabolites, nordiazepam reached measurable levels after the injection of diazepam and clorazepate. 4. It is suggested that differences in the effects of closely related benzodiazepines may not be due solely to their plasma pharmacokinetic properties, but may arise from differences in their intrinsic activity.     

Lead effects on neurobehavioral development in the neonatal rhesus monkey (Macaca mulatta)

Effects of lead exposure on behavioral development during the first month of postnatal life were examined in rhesus monkeys using a multi-item assessment scale developed for the evaluation of neonatal rhesus monkeys. Lead was administered daily beginning at day 8 postpartum at levels that produced blood lead levels of about 20 μg/dl by week 4 (n = 48); controls were treated identically but given vehicle only (n = 24). All monkeys were tested once a week for the first 4 weeks postpartum. The first principal component explained a substantial portion of the variance and was relatively consistent across ages for both groups. Analyses of the individual items and of both conceptually derived and empirically defined summary scores yielded no significant effects of lead. Furthermore, there were no systematic relationships between blood lead level and performance on the test. Correlation coefficients indicated more similarity across age for control monkeys than for lead-exposed monkeys suggesting that continuity of development, as measured by this test, was disrupted by lead. The relationship between outcome on these early assessments and later behavior will be explored in subsequent studies of these monkeys.     

Behavioural sequelae of methaqualone in man and in the monkey (Macaca mulatta).

1 Residual effects in man of methaqualone hydrochloride (400 mg) were studied by adaptive tracking and by reaction time. Performance was measured at 10 h, 13 h, 16 h, 19 h and 34 h after the overnight ingestion of the drug. There was no evidence of impaired performance on adaptive tracking from 10 h to 19 h, but enhanced performance (P = 0.001) was observed 34 h after ingestion. With reaction time an increase (P = 0.01) was observed 10 h and a decrease (P = 0.05) was observed 19 h after ingestion. 2 Effects in the monkey (Macaca mulatta) of methaqualone (20 and 30 mg/kg body weight) were studied by a delayed matching task in which total response time was measured. No consistent effects on matching behaviour or on total response time were observed 2 h after intraperitoneal injection. 3 The studies suggest that methaqualone hydrochloride may be a valuable hypnotic for occasional use by persons involved in skilled activity.     

Teratologic evaluation of metaproterenol in the rhesus monkey (Macaca mulatta)

In order to further evaluate the teratologic potential of metaproterenol (Alupent), an experiment was conducted in timed pregnant rhesus monkeys (Macaca mulatta). Pregnancy was established by bioassay of serum for chorionic gonadotropin according to the method of Tullner and Hertz using the uterine weight of immature mice. Metaproterenol as a 1 mg/ml solution in water was administered by stomach tube at a dose of 5 mg/kg (approximately 3 times the human dose) for 11 consecutive days beginning on days 18–23 of gestation in a total of 12 animals. At approximately day 100 of gestation, the fetus was removed from each monkey by cesarean section. Each fetus was examined for extermal abnormalities, the viscera for any deviations from normal, and the skeletons, after clearing and staining with Alizarin Red S, for any structural deviations. No changes were observed that could be attributed to the administration of metaproterenol. Four concurrently untreated pregnant animals were included.     

Comparative studies with thieno- and benzodiazepines: spatial delayed alternation behaviour in the monkey (Macaca mulatta)

The effects of three benzodiazepines, temazepam, nordiazepam and clobazam, and two triazolo-1,4-thienodiazepines, brotizolam and WE 973, were studied on spatial delayed alternation in the monkey (Macaca mulatto). Experiments were carried out 1 hr after the intraperitoneal injection of doses ranging from 0.5 to 3.0 mg.kg^?1 body weight. No behavioural effects were observed with temazepam and clobazam. Nordiazepam reduced the number of correct responses, and the thienodiazepines reduced the number of correct responses, and increased total response time. In further experiments with doses ranging from 5.0 to 25.0 mg.kg^?1 body weight there was still no effect with clobazam, but temazepam reduced the number of correct responses and increased total response time. There would appear to be differential effects of diazepines on behaviour. The triazolo-1,4-thienodiazepines are particularly potent compared with the benzodiazepines, and the question arises whether they possess specific behavioural activity.     

Metabolism of 14C-labeled doxylamine succinate (Bendectin) in the rhesus monkey (Macaca mulatta)

The time-course of the metabolic fate of [14C]doxylamine was determined after the p.o. administration of 13 mg/kg doxylamine succinate as Bendectin plus [14C]doxylamine succinate to the rhesus monkey. Urine and plasma samples were analyzed by reversed-phase high performance liquid chromatography (HPLC), chemical derivatization, and mass spectrometry. The cumulative 48-hr urinary metabolic profile contained 81% of the administered radiolabeled dose and consisted of at least six radiolabeled peaks. They were peak 1: unknown polar metabolites (8% of dose); peak 2: 2-[1-phenyl-1-(2-pyridinyl)ethoxy] acetic acid, 1-[1-phenyl-1(2-pyridinyl)ethoxy] methanol, and another minor metabolite(s) (31%); peak 3: doxylamine-N-oxide (1%); peak 4a: N,N-didesmethyldoxylamine (17%); peak 4b: doxylamine (4%); and peak 5: N-desmethyldoxylamine (20%). The plasma metabolic profile was the same as the urinary profile except for the absence of doxylamine-N-oxide. The maximum plasma concentrations and elapsed time to attain these concentrations were as follows. Peak 1: 540 ng/mL, 4 hr; peak 2: 1700 ng/mL, 1 hr; peak 4a: 430 ng/mL, 4 hr; peak 4b: 930 ng/mL, 2 hr; and peak 5: 790 ng/mL, 2 hr. These data suggest that in the monkey, doxylamine metabolism follows at least four pathways: a minor pathway to the N-oxide; a minor pathway to unknown polar metabolites; a major pathway to mono- and didesmethyldoxylamine via successive N-demethylation; and a major pathway to side-chain cleavage products (peak 2) via direct side-chain oxidation and/or deamination.     

Toxicity and disposition of 2,3,4,7,8-pentachlorodibenzofuran (4PeCDF) in the rhesus monkey (Macaca mulatta)

The toxicity and disposition of 2,3,4,7,8-pentachlorodibenzofuran (4PeCDF), a ubiquitous and acutely toxic environmental contaminant, was examined in three adult male Rhesus monkeys administered a single iv dose of 34 micrograms (0.1 mumol)/kg. Within 20 min, 4PeCDF was eliminated from the blood and was distributed to the liver, skin, adipose, and muscle tissues. Excretion occurred primarily via the feces with a minimum whole body half-life approximately 38 days. Within 7-14 days after administration, the packed cell volume and serum triglyceride and bile acid concentrations were significantly increased while serum cholesterol, protein, and albumin concentrations were decreased relative to pretreatment levels. Thyroid hormone levels were also altered with an increase in TSH and a decrease in T3 and T4 concentrations. After 28 days, two monkeys began exhibiting alopecia, hyperkeratinization of the toe and finger nails, facial chloracne-like lesions, and loss of body weight. They subsequently died 40 and 48 days after treatment. Similar symptoms of toxicity were observed in the third animal 58 days after 4PeCDF administration, but this animal appeared to fully recover and was administered 4PeCDF orally and [3H]1,2,3,7,8-pentachloro-dibenzofuran (1PeCDF) dermally 238 days after the initial iv dose. In this animal, approximately 2% of an oral dose of [14C]-4PeCDF was absorbed from the stomach and small intestine in 6 hr and was distributed mainly to the muscle and skin and less than 99% of a dermal dose of 1PeCDF remained at the site of application. Pathological findings in the monkeys that died indicated hyperplastic and metaplastic changes in the gastric mucosa, the Meibomian glands of the eyelid, and the ceruminous glands of the ear. Regression of these lesions was present in the surviving animal. Therefore, 4PeCDF produces dioxin-like toxicity in the monkey similar to that reported for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and in the same dose range.     

β-Adrenoceptor antagonists: studies on behaviour (delayed differentiation) in the monkey (Macaca mulatta)

1 Activity of six β-adrenoceptor antagonists was studied on behavioural activity (delayed differentiation) in the monkey (Macaca mulatta). The drugs, three relatively lipophilic antagonists (propranolol, oxprenolol and metoprolol), and three relatively hydrophilic antagonists (acebutolol, atenolol and sotalol), were given by intraperitoneal injection (5 to 30 mg/kg).

2 With atenolol (25 to 30 mg/kg), total response time was increased, but there was no effect on the number of correct responses. With acebutolol (25 to 30 mg/kg), the number of correct responses was reduced, but there was no effect on total response time. With metoprolol (25 to 30 mg/kg), there was an increase in total response time and a decrease in the number of correct responses, and correct responses were decreased 4 h after injection over the whole dose range (5 to 30 mg/kg).

3 Some animals failed to respond or complete the task with 30 mg/kg oxprenolol, 25 mg/kg sotalol and 20 mg/kg propranolol. With 25 mg/kg oxprenolol, the total response time was increased and the number of correct responses was decreased. With 5-20 mg/kg sotalol, total response time was increased, but there was no effect on the number of correct responses. With 15 mg/kg of (±)-propranolol and its isomers, there were increases in total response time and decreases in correct responses.

4 The studies suggest that lipophilic antagonists, such as propranolol, oxprenolol and metoprolol, are likely to have, at least, effects on the central nervous system, while hydrophilic antagonists may modify the peripheral nervous system. In the dose-ranges studied, propranolol had the greatest, and atenolol and acebutolol had the least effects. Atenolol and acebutolol may prove to be particularly useful in man when disturbances of the nervous system are to be avoided.

     

Primacy and recency effects in rhesus monkeys (Macaca mulatta) using a serial probe recognition task I. Effects of diazepam

In this study, we evaluated the effects of diazepam (0.2, 0.8, 1.6 and 3.2 mg/kg; IM) on the primacy and recency memory effects in four rhesus monkeys trained on a six-item serial probe recognition (SPR) task. Only the highest dose of diazepam (3.2 mg/kg) consistently affected the shape of the monkeys' serial position curves. Accuracy on the probe trials was disrupted for list items which occurred in the middle portion and recency memory component of the serial position curve, without affecting the primacy component. Diazepam, however, also produced several nonspecific effects on SPR performance. Both the 1.6 and 3.2 mg/kg diazepam doses disrupted accuracy on the non-matching probe trials, and the 3.2 mg/kg dose caused an increase in response latencies which were unrelated to any one component of the serial position curve. This is the first demonstration in nonhuman primates showing that the primacy and recency memory effects can be differentiated on the basis of diazepam dose.The opinions and assertions contained in this report are the private views of the author and are not to be construed as official or as reflecting the views of the Army or the Department of Defense. In conducting the research described in this report, the investigators adhered to the Animal Welfare Act and the Guide for the Care and Use of Laboratory Animals, NIH Publication No. 86-23     

Gestational and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin affects social behaviors between developing rhesus monkeys (Macaca mulatta)

Pregnant rhesus monkeys (Macaca mulatta) were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at 30 and 300 ng/kg by subcutaneous injection at gestational day 20, followed by additional injections of TCDD (1.5 and 15 ng/kg, respectively) every 30 days till 90 days after parturition. The offspring delivered from these experimentally TCDD-exposed mothers were subjected to a series of behavioral tests after the weaning at 12–14 months old (MO): a finger maze learning task (12–15 MO), encounter tests between two monkeys (at 12–15 and 24–27 MO), and an eye-contact test (23–26 MO) to estimate learning ability, social interaction with a peer subject, and interest or hostility to a human observer, respectively. TCDD exposure had no significant effect on learning ability or interest/hostility to an observer. It did, however, significantly affect behavioral characteristics in the encounter tests. In the first encounter test, monkeys exposed to TCDD showed more visual exploration and mutual proximity but less stereotypy behavior compared to control monkeys. In the second encounter test, these differences seemed to disappear, suggesting that the behavioral effects of TCDD exposure in the encounter tests might disappear as the monkey develops. This study produced evidence of the behavioral toxicity of TCDD in social interactions using non-human primates.     

Distribution of GABA(B) binding sites in the thalamus and basal ganglia of the rhesus monkey (Macaca mulatta)

The regional distribution of GABA(B) receptor binding sites in the thalamus and basal ganglia of rhesus monkey has been determined by receptor autoradiography using the agonist ligand, [3H]-GABA. Whilst binding sites were evident throughout the thalamus, the internuclear differences in the Bmax were up to 10-fold. In the basal ganglia the binding density was on average lower than in the thalamus. The highest number of binding sites was in striatum followed closely by substantia nigra. In both the thalamus and basal ganglia, the binding density was higher than previously described in the rat. Although our results do not allow us to differentiate between presynaptic and postsynaptic locations of GABA(B) sites we conclude that with a few exceptions the distribution pattern of GABA(B) binding sites in the monkey thalamus appears to correlate with the known innervation from the NRT.     

Effect of dietary chronic cadmium exposure on cell-mediated immune response in rhesus monkey (Macaca mulatta)

Rhesus monkeys (Macaca mulatta) were daily exposed orally to cadmium (Cd) at 5 mg/kg body wt in diet for a period of 2 and 6 months. Significant amount of Cd accumulated in liver, kidney and spleen after its exposure to monkeys. Cell mediated immune response was assessed by the responsiveness of peripheral blood lymphocytes (PBL) to phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM). Even after 6 months of exposure, Cd increased DNA synthesis, although not significantly, in unstimulated and mitogen stimulated lymphocytes. Stimulation Index (SI), however, decreased largely due to increased unstimulated [( 3H]thymidine incorporation) observed after Cd exposure. It, therefore, indicates that Cd is not immunosuppressive in primates, phylogenetically closer to humans.     

Inosine induces acute hyperuricaemia in rhesus monkey (Macaca mulatta) as a potential disease animal model

ContextThe uric acid metabolism pathway is more similar in primates and humans than in rodents. However, there are no reports of using primates to establish animal models of hyperuricaemia (HUA).ObjectivesTo establish an animal model highly related to HUA in humans.Materials and methodsInosine (75, 100 and 200 mg/kg) was intraperitoneally administered to adult male rhesus monkeys (n = 5/group). Blood samples were collected over 8 h, and serum uric acid (SUA) level was determined using commercial assay kits. XO and PNP expression in the liver and URAT1, OAT4 and ABCG2 expression in the kidneys were examined by qPCR and Western blotting to assess the effects of inosine on purine and uric acid metabolism. The validity of the acute HUA model was assessed using ulodesine, allopurinol and febuxostat.ResultsInosine (200 mg/kg) effectively increased the SUA level in rhesus monkeys from 51.77 ± 14.48 at 0 h to 178.32 ± 14.47 μmol/L within 30 min and to peak levels (201.41 ± 42.73 μmol/L) at 1 h. PNP mRNA level was increased, whereas XO mRNA and protein levels in the liver were decreased by the inosine group compared with those in the control group. No changes in mRNA and protein levels of the renal uric acid transporter were observed. Ulodesine, allopurinol and febuxostat eliminated the inosine-induced elevation in SUA in tested monkeys.ConclusionsAn acute HUA animal model with high reproducibility was induced; it can be applied to evaluate new anti-HUA drugs in vivo and explore the disease pathogenesis.     

Quantitative assessment of spermatogenesis in rats given 1-amino-3 chloro-2 propanol hydrochloride (CL 88, 236)

A quantitative histomorphometric assessment of testicular spermatogenesis was undertaken on testes from rats which had received 1-amino-3 chloro-2 propanol hydrochloride (CL 88, 236) at oral doses of 0, 50, 250 or 500 mg/ kg/day for 12 weeks. Rats which developed epididymal sperm granulomata or severe atrophy of the germinal epithelium were excluded from quantitative examination. Pathological changes in the epididymis and seminiferous epithelium were not strongly correlated. CL 88, 236 administered at 50 mg/ kg/day was without effect on the histomorphometry of the seminiferous epithelium, although epididymal lesions occurred at this dose. At higher doses a quantitative reduction in testicular spermatids was evident. It appears important to differentiate between the selective antifertility action of CL 88, 236 on the biochemistry of epididymal spermatozoa and the disruption of epididymal physiology, and testicular spermatogenesis found at unusually high doses.     

Liver function studies on rhesus monkeys (Macaca mulatta) following the administration of hydrazine sulfate

Hydrazine sulfate (Hs), a known occupational toxin and putative cancer therapeutic agent, was administered iv at various doses to rhesus monkeys in an effort to measure its effects upon the liver. Function tests included indocyanine clearance (ICG Vmax and Km), serum bile acid levels and serum enzyme activities, including alanine aminotransferase, gamma glutamyl transferase, and a panel of 19 other blood chemical constituents. Hepatic function and other biochemical tests were generally within the normal range following single-dose Hs administration (10-40 mg/kg) and did not suggest the presence of significant liver injury. Two monkeys receiving 80 mg/kg Hs exhibited extensive hepatic lipidosis without biochemical or histologic signs of necrosis. Hs, administered iv, appears to produce little or no hepatic toxicity.