Adult Male Rhesus Research Articles

RF9 Rescues Cortisol-Induced Repression of Testosterone Levels in Adult Male Macaques.

Cortisol inhibits hypothalamic-pituitary-gonadal (HPG) axis whereas RF9, a potent agonist of kisspeptin receptor (GPR54) activates HPG-axis during fasting-induced stress and under normal physiological conditions. However, the effect of RF9 on the cortisol-induced repressed HPG-axis is not studied yet. This study investigated whether exogenous cortisol-induced repression of the HPG-axis can be rescued by RF9. Six intact adult male rhesus monkeys (Macaca mulatta) habituated to chair-restraint were administered hydrocortisone sodium succinate at a rate of 20 mg/kg of body weight (BW) per day for 12 days. Single blood sample was taken by venipuncture from each animal on alternate days for hormones analyses. On experimental day 12, hydrocortisone treated monkeys received a single intravenous bolus of RF9 (n = 3) and vehicle (n = 3). The animals were bled for a period of 4 h at 60 min intervals from an indwelling cannula in the saphenous vein. RF9 was administered intravenously at the dose of 0.1 mg/kg BW immediately after taking 0 min sample. Plasma cortisol and testosterone concentrations were measured by using specific enzyme immunoassays. Hydrocortisone treatment increased plasma cortisol levels (P ≤ 0.0001) and decreased plasma testosterone (P ≤ 0.0127) levels. Interestingly, compared to vehicle, RF9 treatment significantly increased plasma testosterone levels at 120 min (P ≤ 0.0037), 180 min (P ≤ 0.0016), and 240 min (P ≤ 0.0001) intervals in the hydrocortisone treated monkeys. From these results, we concluded that RF9 administration relieves the suppressed HPG-axis in term of plasma testosterone levels in the cortisol treated monkeys.

Alprazolam-induced EEG spectral power changes in rhesus monkeys: a translational model for the evaluation of the behavioral effects of benzodiazepines.

Benzodiazepines induce electroencephalography (EEG) changes in rodents and humans that are associated with distinct behavioral effects and have been proposed as quantitative biomarkers for GABAA receptor modulation. Specifically, central EEG beta and occipital EEG delta activity have been associated with anxiolysis and sedation, respectively. The extent to which nonhuman primates show the same dose- and topography-dependent effects remained unknown. We aimed at establishing a nonhuman primate model for the evaluation of benzodiazepine EEG pharmacology. Four adult male rhesus monkeys were prepared with fully implantable telemetry devices that monitored activity, peripheral body temperature, and contained two EEG (central and occipital), one electromyography (EMG), and one electrooculography channel. We investigated daytime alprazolam-induced changes in EEG spectral power, sleep-wake states, EMG activity, locomotor activity, and body temperature. Alprazolam (0.01-1.8 mg/kg, i.m.) or vehicle was administered acutely, and telemetry recording was conducted for 1 h. Daytime alprazolam dose-dependently increased central EEG power (including beta activity), increased occipital EEG delta power, and decreased occipital EEG alpha, theta, and sigma power. There was an ~8-fold difference in the potency of alprazolam to increase central EEG beta vs. occipital EEG delta activity (based on relative EEG power). The highest dose, which increased both central EEG beta and occipital EEG delta relative power, induced sedative effects (increased time spent in N1 and N2 sleep stages) and decreased peripheral body temperature and locomotor activity. Alprazolam induces dose- and topography-dependent EEG changes in rhesus monkeys and provides a valuable model for studying benzodiazepine pharmacology.

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

Context The 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). Objectives To establish an animal model highly related to HUA in humans. Materials and methods Inosine (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. Results Inosine (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. Conclusions An 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.

Use of Introduction Enclosures to Integrate Multimale Cohorts into Groups of Female Rhesus Macaques (Macaca mulatta).

Integrating animals into a new group is a challenge for both free-ranging and captive adult male rhesus monkeys (Macaca mulatta), and for females in groups receiving new males. To ensure the genetic viability of the population, however, male transfers must occur in both natural and captive settings. To facilitate the introduction of groups of adult males to adult females, we designed a new enclosure that is attached to the outdoor compound where females are housed. Here we describe the construction of 3 introduction enclosures, their use during 4 introductions of groups of adult males to adult females, a brief comparison of introduction success rates associated with the new introduction enclosures with those of our traditional male introduction method, and a critique by the various groups of staff members working with the new enclosures. Overall, the introduction enclosures benefitted both the macaques and the facility personnel and appear to be a useful enhancement to our process of integrating breeding groups.

Zika virus in rhesus macaque semen and reproductive tract tissues: a pilot study of acute infection†.

Although sexual transmission of Zika virus (ZIKV) is well-documented, the viral reservoir(s) in the male reproductive tract remains uncertain in humans and immune-intact animal models. We evaluated the presence of ZIKV in a rhesus macaque pilot study to determine persistence in semen, assess the impact of infection on sperm functional characteristics, and define the viral reservoir in the male reproductive tract. Five adult male rhesus monkeys were inoculated with 105 PFU of Asian-lineage ZIKV isolate PRVABC59, and two males were inoculated with the same dose of African-lineage ZIKV DAKAR41524. Viremia and viral RNA (vRNA) shedding in semen were monitored, and a cohort of animals were necropsied for tissue collection to assess tissue vRNA burden and histopathology. All animals exhibited viremia for limited periods (1-11days); duration of shedding did not differ significantly between viral isolates. There were sporadic low levels of vRNA in the semen from some, but not all animals. Viral RNA levels in reproductive tract tissues were also modest and present in the epididymis in three of five cases, one case in the vas deferens, but not detected in testis, seminal vesicles or prostate. ZIKV infection did not impact semen motility parameters as assessed by computer-assisted sperm analysis. Despite some evidence of prolonged ZIKV RNA shedding in human semen and high tropism of ZIKV for male reproductive tract tissues in mice deficient in Type 1 interferon signaling, in the rhesus macaques assessed in this pilot study, we did not consistently find ZIKV RNA in the male reproductive tract.

Peripheral Administration of RF9 Does Not Affect Hypothalamic-PituitaryGonadal Axis in Normal Fed Adult Male Macaque

Stress represses hypothalamic-pituitary-gonadal axis (HPG-axis) but RF9, a synthetic peptide, rescues such repression. To assess the role of RF9 in regulating HPG-axis under normal physiological conditions in higher primates, RF9 was administered to intact adult male rhesus monkeys and response of the HPG-axis was examined by measuring plasma testosterone as an end parameter of the axis. Control group (n=4) received normal saline whereas the treated group (n=4) received RF9. On the first day of experiment, four bolus injections of normal saline (1ml/animal) were administered intravenously at 2-hr interval to the control monkeys. Similarly, on the second day of experiment, treated group received four iv bolus injections of RF9 (0.1mg/kg BW) at 2-hr interval. Serial blood samples were collected at 20 min interval during a 6-hr period which started just after first saline/RF9 injection. Plasma testosterone levels were measured by using a specific EIA. Overall means of plasma testosterone levels and plasma testosterone area under curve (AUC) and overall mean testosterone and mean testosterone AUC in short time windows following each injection of RF9 and saline were comparable between the groups. Our results demonstrate that RF9 has no role in regulating HPG-axis under normal physiological conditions in adult male monkeys.

Intranasal salvinorin A improves neurological outcome in rhesus monkey ischemic stroke model using autologous blood clot

Salvinorin A (SA) exerts neuroprotection and improves neurological outcomes in ischemic stroke models in rodents. In this study, we investigated whether intranasal SA administration could improve neurological outcomes in a monkey ischemic stroke model. The stroke model was induced in adult male rhesus monkeys by occluding the middle cerebral artery M2 segment with an autologous blood clot. Eight adult rhesus monkeys were randomly administered SA or 10% dimethyl sulfoxide as control 20 min after ischemia. Magnetic resonance imaging was used to confirm the ischemia and extent of injury. Neurological function was evaluated using the Non-Human Primate Stroke Scale (NHPSS) over a 28-day observation period. SA significantly reduced infarct volume (3.9 ± 0.7 cm3 vs. 7.2 ± 1.0 cm3; P = 0.002), occupying effect (0.3 ± 0.2% vs. 1.4 ± 0.3%; P = 0.002), and diffusion limitation in the lesion (−28.2 ± 11.0% vs. −51.5 ± 7.1%; P = 0.012) when compared to the control group. SA significantly reduced the NHPSS scores to almost normal in a 28-day observation period as compared to the control group (P = 0.005). Intranasal SA reduces infarct volume and improves neurological outcomes in a rhesus monkey ischemic stroke model using autologous blood clot.

A longitudinal study of brain volume changes in rhesus macaque model infected with SIV.

Given the current lack of understanding of brain volume changes caused by HIV infection, this study aimed to longitudinally assess the changes in regional brain tissue volume following HIV infection and to explore its relationship with peripheral blood absolute CD4+ lymphocyte count (CD4+), the percentage of monocytes in plasma(MON%) and cerebrospinal fluid viral load (CFVL).Four adult male rhesus monkeys were examined in healthy status and following infection with simian immunodeficiency virus using high-resolution 3D T1-weighted sagittal whole brain magnetic resonance imaging. DPABI and SPM were used to process and record changes in brain tissue volume. Correlation analyses were then used to explore the above relationships. Compared with brain tissue volume during the healthy stage, there was no change at 12 and 24weeks postinoculation (12wpi, 24wpi). At 36wpi, 48wpi, and 60wpi, basal ganglia, left inferior temporal gyrus, left occipital gyrus, and left superior frontal gyrus exhibited varying degrees of atrophy. There was no association found between CD4+, MON%, CFVL, and brain volume loss in any brain region. Our research demonstrated that in the early stage of HIV infection, local brain tissue atrophy can be demonstrated by MRI technique; furthermore, MRI can identify the earliest site of atrophy as well as the most severely affected site. Although there was no significant correlation between brain tissue volume loss and CD4+, MON%, and CFVL, our findings provided some evidence in the application of volumetric MR imaging in the early diagnosis and treatment follow-up of patients with HIV infection.

Quantification of observable behaviors induced by typical and atypical kappa-opioid receptoragonists in male rhesus monkeys.

Kappa-opioid receptor (KOR) agonists are antinociceptive but have side effects that limit their therapeutic utility. New KOR agonists have been developed that are fully efficacious at the KOR but may produce fewer or reduced side effects that are typicalof KOR agonists. We determined behavioral profiles for typical and atypical KOR agonists purported to differ in intracellular-signaling profiles as well as a mu-opioid receptor (MOR) agonist, oxycodone, using a behavioral scoring system based on Novak et al. (Am J Primatol 28:124-138, 1992, Am J Primatol 46:213-227, 1998) and modified to quantify drug-induced effects (e.g., Duke et al. J Pharmacol Exp Ther 366:145-157, 2018). Six adult male rhesus monkeys were administered a range of doses of the typical KOR agonists, U50-488H (0.0032-0.1mg/kg) and salvinorin A (0.00032-0.01mg/kg); the atypical KOR agonists, nalfurafine (0.0001-0.001mg/kg) and triazole 1.1 (0.01-0.32mg/kg); the MOR agonist, oxycodone (0.0032-0.32mg/kg); and as controls, cocaine (0.032-0.32mg/kg) and ketamine (0.32-10mg/kg). For time-course determinations, the largest dose of each KOR agonist or MOR agonist was administered across timepoints (10-320min). In mixture conditions, oxycodone (0.1mg/kg) was followed by KOR-agonist administration. Typical KOR agonists produced sedative-like and motor-impairing effects. Nalfurafine was similar to typical KOR agonists on most outcomes, and triazole 1.1 produced no effects on its own except for reducing scratch during time-course determinations. In the mixture, all KOR agonists reduced oxycodone-induced scratching, U50-488H and nalfurafine reduced species-typical activity, and U50-488H increased rest/sleep posture. Atypical "biased" KOR agonists produce side-effect profiles that are relatively benign (triazole 1.1) or reduced (nalfurafine) compared to typical KOR agonists.

Kappa opioid agonists reduce oxycodone self-administration in male rhesus monkeys.

Combinations of mu and kappa opioid receptor (KOR) agonists have been proposed as potential analgesic formulations with reduced abuse liability. The current studies extend previous work by investigating the typical KOR agonist, salvinorin A, and the atypical KOR agonist, nalfurafine, as deterrents of oxycodone self-administration using a progressive ratio (PR) schedule of reinforcement. In separate experiments, adult male rhesus monkeys (N= 4/experiment) were trained under a PR schedule of reinforcement to self-administer cocaine (0.1mg/kg/injection) and saline on alternating days. Oxycodone (0.01-0.1mg/kg/injection) alone and combined with salvinorin A (experiment 1; 0.006, 0.012mg/kg/injection) or nalfurafine (experiment 2; 0.0001-0.00032mg/kg/injection) were tested within the alternating cocaine and saline baseline. The mechanism of nalfurafine's effects on oxycodone self-administration was investigated via pretreatment with the KOR antagonist, nor-binaltorphimine (nor-BNI; 10mg/kg; i.m.). All subjects self-administered oxycodone alone above saline levels at sufficiently large doses, and combining salvinorin A or nalfurafine with oxycodone reduced the mean number of injections per session to saline levels (experiment 1) or to levels that were significantly lower than oxycodone alone (experiment 2). The ability of nalfurafine to reduce oxycodone self-administration was reversed by pretreatment with nor-BNI. These results demonstrate that KOR agonists, including the clinically used KOR agonist, nalfurafine, can punish self-administration of a prescription opioid analgesic, oxycodone, in rhesus monkeys and that nalfurafine's punishing effect is KOR-dependent. Combinations of KOR agonists with prescription opioids may have reduced abuse liability.

Cannabinoid Modulation of Food-Cocaine Choice in Male Rhesus Monkeys.

Marijuana and other cannabinoid compounds are widely used by cocaine users. Preclinical animal studies suggest that these compounds can increase the reinforcing effects of cocaine under some schedules of cocaine self-administration and reinstatement, but not in all cases. To date, no studies have used a food-cocaine concurrent choice procedure, which allows for assessment of drug effects on response allocation, not just changes in cocaine self-administration. The goal of the present study was to examine the effects of compounds differing in their efficacy at the cannabinoid receptor (CBR) on cocaine self-administration using a food-drug choice procedure in monkeys. Four adult male rhesus monkeys were trained to self-administer cocaine in the context of an alternative food (1.0-g banana-flavored pellets) reinforcer, such that complete cocaine dose-response curves (0, 0.003-0.1 mg/kg per injection) were determined each session. Monkeys were tested acutely with the CBR full agonist CP 55,940 (0.001-0.01 mg/kg); the CBR partial agonist Δ9-tetrahydrocannabinol (THC; 0.03-0.3 mg/kg), which is also the primary active ingredient in marijuana and the CBR antagonist rimonabant (0.3-3.0 mg/kg). Cocaine choice increased in a dose-dependent manner. Acute treatment with CP 55,940 decreased cocaine choice, whereas THC and rimonabant enhanced the reinforcing effects of cocaine. Chronic (7-day) treatment with CP 55,940 resulted in tolerance to the decreases in cocaine choice. These findings with Δ9-THC provide support for a potential mechanism for co-abuse of marijuana and cocaine. Additional research with chronic treatment with full CBR agonists on attenuating the reinforcing strength of cocaine is warranted. SIGNIFICANCE STATEMENT: Co-abuse of tetrahydrocannabinol and cocaine is a significant public health problem. The use of animal models allows for the determination of how cannabinoid receptor stimulation or blockade influences the reinforcing strength of cocaine.

Peripherally administered KP-10 prevents development of insulin-induced hypoglycemic shock in diabetic rhesus monkeys

This study investigated whether kisspeptin-10 (KP-10) prevents diabetic rhesus monkeys from insulin-induced hypoglycemic shock. Thirty-six adult male rhesus monkeys were used, six in each group. Diabetes was induced with streptozotocin (45mg/kg b.w.; single dose i.v.). Groups were as: saline control, insulin alone, pre-insulin (treated with KP-10, 30 min before insulin), post-insulin (treated with KP-10, 30min after insulin), treated with premix dose of KP-10 (50μg) and insulin, and the group treated with the kisspeptin antagonist P234 (50μg). Following an overnight fast, each animal was subjected to respective treatment, and blood glucose concentrations were recorded every 30-min interval for 3h. Intergroup comparisons demonstrated that treatment with KP-10 prior to insulin administration and kisspeptin-insulin premix treatment allowed blood glucose levels to rise to significantly higher levels (p < 0.001) by 180min in diabetic and healthy animals compared to treatment with insulin alone. However, intragroup comparisons revealed a significant decrease in blood glucose level in diabetic animals only. Treatment with P234 antagonist followed by insulin administration abolished the preventive action of kisspeptin, whereby blood glucose decreased significantly (p < 0.001) in both diabetic and healthy animals. KP-10 post-insulin treatment, however, remained ineffective and led, instead, to significantly decreased glucose concentrations by 180min in both diabetic and healthy animals when compared to animals treated with insulin alone. KP-10 bears therapeutic potential to prevent hypoglycemic shock that may sometimes occur during intensive insulin therapy. Several pharmacological aspects of its interaction with insulin and other drugs, however, remain to be investigated.

Self-administration of the synthetic cathinones 3,4-methylenedioxypyrovalerone (MDPV) and α-pyrrolidinopentiophenone (α-PVP) in rhesus monkeys.

The availability and abuse of synthetic analogues of cathinone have increased dramatically around the world. Synthetic cathinones, such as 3,4-methylenedioxypyrovalerone [MDPV] and α-pyrrolidinopentiophenone [α-PVP], are cocaine-like inhibitors of monoamine transporters and common constituents of "bath salts" or "flakka" preparations. Studies in rats suggest that MDPV and α-PVP are 3 to 4-fold more effective reinforcers than cocaine; however, comparisons of the relative reinforcing effectiveness of MDPV and α-PVP have not been reported in other species. Accordingly, in the present study, 4 adult male rhesus monkeys responding under a progressive ratio schedule of reinforcement were used to characterize the reinforcing effects of MDPV and α-PVP and to compare directly these effects with those of cocaine and methamphetamine. MDPV was the most potent reinforcer, followed by α-PVP, methamphetamine, and cocaine. α-PVP was the most effective reinforcer, followed by MDPV, cocaine, and methamphetamine. In addition to making more responses to obtain MDPV and α-PVP, monkeys also responded for longer periods of time when MDPV or α-PVP was available compared with when either cocaine or methamphetamine was available for infusion. These studies confirm recent reports from rodents and provide strong evidence that the synthetic cathinones MDPV and α-PVP are capable of maintaining high levels of responding for prolonged periods of time, and that they function as more effective reinforcers than either cocaine or methamphetamine. The relative strength of these reinforcing effects may account for the high rates of "bath salts" use reported in humans.

Cross-species convergence in pupillary response: understanding human anxiety via non-human primate amygdala lesion.

Few studies have used matched affective paradigms to compare humans and non-human primates. In monkeys with amygdala lesions and youth with anxiety disorders, we examined cross-species pupillary responses during a saccade-based, affective attentional capture task. Given evidence of enhanced amygdala function in anxiety, we hypothesized that opposite patterns would emerge in lesioned monkeys and anxious participants. A total of 53 unmedicated youths (27 anxious, 26 healthy) and 8 adult male rhesus monkeys (Macaca mulatta) completed matched behavioral paradigms. Four monkeys received bilateral excitotoxic amygdala lesions and four served as unoperated controls. Compared to healthy youth, anxious youth exhibited increased pupillary constriction in response to emotional and non-emotional distractors (F(1,48) = 6.28, P=0.02, η2p= 0.12). Pupillary response was associated significantly with anxiety symptoms severity (F(1,48) = 5.59, P=0.02, η2p= 0.10). As hypothesized, lesioned monkeys exhibited the opposite pattern i.e. decreased pupillary constriction in response to distractors, compared to unoperated control monkeys (F(1,32) = 24.22, P<0.001, η2= 0.33). Amygdala lesioned monkeys and youth with anxiety disorders show opposite patterns of pupil constriction in the context of an affective distractor task. Such findings suggest the presence of altered amygdala circuitry functioning in anxiety. Future lesion and human neuroimaging work might examine the way in which specific amygdala sub-nuclei and downstream circuits mediate these effects.

Development and validation of a primate model for liver fibrosis

IntroductionMany liver diseases involve liver fibrosis. Most preclinical studies of liver fibrosis are carried out in small animals such as rodents, and thus lack direct potential for extrapolation to human diseases. The aim of the current study was to develop a primate model for liver fibrosis with greater relevance to translational research. MethodsLiver fibrosis was induced in adult male healthy rhesus monkeys using repeated CCl4 treatment (40% in olive oil, 1.5 ml/kg once every 3 days via peritoneal injection, subcutaneous injection or gastric gavage). Liver biopsy was conducted at various time points for histologic examination. Blood samples were taken for standard liver function test. ResultsGastric gavage was the optimal approach for establishing stably liver fibrosis without animal loss due to toxicity. The progression of fibrosis appeared to involve epithelial to mesenchymal transition and hepatic ductular reaction. ConclusionRepeated CCl4 gavage in rhesus monkeys results in stable liver fibrosis. Such a model may be an effective platform for future studies of human liver fibrosis.

The Accuracy and Feasibility of Robotic Assisted Lead Implantation in Nonhuman Primates

Deep brain stimulation (DBS) and stereo-electroencephalography (SEEG) electrode implantation are the most important and frequent manipulations in nonhuman primates (NHP) neuromodulation research. However, traditional methods tend to be arduous and inaccurate. Twelve adult male rhesus monkeys were selected for the study, with six subthalamic nucleus (STN) DBS, six anterior nucleus of the thalamus (ANT) DBS and six hippocampus-SEEG (Hippo-SEEG) electrodes implantation. Mean Euclidean errors of entrance and the target were calculated by postoperative image fusion, and the correlation between entrance and target error, as well as the differences among the various manipulations, were analyzed. The accuracy of target was further confirmed by gross anatomy examination. Moreover, the time consumption was recorded. The mean (±SD) Euclidean errors of the target point and entry point of the three manipulations were STN-DBS: 1.05 ± 0.54 mm and 0.52 ± 0.17 mm; ANT-DBS: 1.12 ± 0.74 mm and 0.58 ± 0.24 mm; and Hippo-SEEG: 2.68 ± 1.03 mm and 1.47 ± 0.63 mm. Significant differences were observed in both target and entry point errors between the DBS and Hippo-SEEG groups, with superior accuracy in the DBS group. The entrance errors had a significantly positive correlation with the target errors in the STN-DBS and Hippo-SEEG groups. Moreover, the time consumption in robotic surgery was much shorter than that in the traditional method, without any severe complications. The application of robot-assisted lead implantation in NHP neuromodulation research is feasible, accurate, safe, and efficient, and can prospectively be beneficial to neurological studies.

Abuse Potential of Phendimetrazine and its Effects on Cocaine Self‐Administration in Rhesus Monkeys

Cocaine use disorder (CUD) continues to be a major public health and social problem with &gt;1.5 million users resulting in 14,556 deaths in 2017 in the United States and with no FDA‐approved medications available (Volkow and Koob, 2016). Preclinical studies in nonhuman primates have shown that monoamine releasers such as amphetamine can reduce the reinforcing strength of cocaine under several schedules of cocaine self‐administration (SA; Czoty et al. 2010; Negus et al. 2003a, b). However, the high abuse potential of this category of drugs has hindered advancement of their clinical use for treatment of CUD. More recently, preclinical researchers have investigated phendimetrazine (PDM), an FDA‐approved Schedule III anorectic agent, with evidence of efficacy in animal models (Banks and Negus, 2013; Czoty et al. 2016). As a pro‐drug for the monoamine releaser phenmetrazine, PDM has a slow onset and long duration of action. Only two studies (Griffiths et al. 1976; Corwin et al. 1987) have evaluated the reinforcing effects of PDM, with opposite conclusions. The goal of the present study was to compare, in the same subjects, the efficacy of PDM to decrease cocaine SA and the reinforcing strength of PDM relative to cocaine. For 5 consecutive days, three adult male rhesus monkeys responded under a daily fixed‐ratio 20 schedule of food presentation, which, on the fifth day, was followed by a progressive‐ratio (PR) schedule of cocaine (0.003–0.3 mg/kg/injection) presentation (limited hold 30‐min, maximum 4‐hr). PDM was administered daily (1.0–6.0 mg/kg, PO, BID). The primary dependent variable under the PR schedule was the number of injections delivered. Under baseline conditions, monkeys typically earned 10 food reinforcers and the number of cocaine injections was characterized as an inverted U‐shaped function of dose. Under treatment conditions, in two subjects, food‐maintained responding was disrupted at higher PDM doses that also decreased cocaine SA. In the third subject, food reinforcement was not affected and PDM did not show efficacy in decreasing cocaine SA. When PDM (0.1–1.0 mg/kg/injection) was substituted for cocaine, it functioned as a reinforcer in all three subjects; the number of injections observed at peak doses of PDM (0.3 and 1.0 mg/kg/injection) were similar to those observed at the peak dose of cocaine (0.03 mg/kg/injection). These findings suggest that PDM has abuse liability and was ineffective in decreasing cocaine SA. These data do not support the use of PDM as a potential treatment for CUD.Support or Funding InformationP50 DA06634‐27This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Perturbation of Macaque Supplementary Motor Area Produces Context-Independent Changes in the Probability of Movement Initiation

The contribution of the supplementary motor area (SMA) to movement initiation remains unclear. SMA exhibits premovement activity across a variety of contexts, including externally cued and self-initiated movements. Yet SMA lesions impair initiation primarily for self-initiated movements. Does SMA influence initiation across contexts or does it play a more specialized role, perhaps contributing only when initiation is less dependent on external cues? To address this question, we perturbed SMA activity via microstimulation at variable times before movement onset. Experiments used two adult male rhesus monkeys trained on a reaching task. We used three contexts that differed regarding how tightly movement initiation was linked to external cues. Movement kinematics were not altered by microstimulation. Instead, microstimulation induced a variety of changes in the timing of movement initiation, with different effects dominating for different contexts. Despite their diversity, these changes could be explained by a simple model where microstimulation has a stereotyped impact on the probability of initiation. Surprisingly, a unified model accounted for effects across all three contexts, regardless of whether initiation was determined more by external cues versus internal considerations. All effects were present for stimulation both contralateral and ipsilateral to the moving arm. Thus, the probability of initiating a pending movement is altered by perturbation of SMA activity. However, changes in initiation probability are independent of the balance of internal and external factors that establish the baseline initiation probability.SIGNIFICANCE STATEMENT The role of the supplementary motor area (SMA) in initiating movement remains unclear. Lesion experiments suggest that SMA makes a critical contribution only for self-initiated movements. Yet SMA is active before movements made under a range of contexts, suggesting a less-specialized role in movement initiation. Here, we use microstimulation to probe the role of SMA across a range of behavioral contexts that vary in the degree to which movement onset is influenced by external cues. We demonstrate that microstimulation produces a temporally stereotyped change in the probability of initiation that is independent of context. These results argue that SMA participates in the computations that lead to movement initiation and does so across a variety of contexts.

The DTI changes and peripheral blood test results corroborate the early brain damage of SIV-infected rhesus

ObjectIn China, there are 789617 patients infected by HIV/AIDS until March 2018. DTI is sensitive to the integrity of tissue microstructure. The changes in SIV-mac239 infected rhesus monkey's structure and brain function are very similar to humans. This study is designed to study the relationship of DTI parameters(FA, AD) values and the peripheral blood examination results at the time before infection, 12 weeks after infection and 24 weeks after infection. MethodFour healthy adult male rhesus monkeys(aged 3–5 years, weighted 5.0–7.0 kg) were involved. Linear regression analysis was applied to analyze the correlation between DTI parameters(FA, AD) and the peripheral blood examination results. ResultsThe results showed as the FA value decreased, the mean reticulocyte volume(MRV) increased, the mean corpuscular hemoglobin concentration(MCHC) increased, the total protein(TP) increased, the immature lymphocytes(IML%) increased, the plasma prothrombin time(PT) increased and globulin levels(GLOB) increased. As the AD values increased, reticulocyte count(RET%) increased, hematocrit(HCT) increased, CD3+ lymphocyte counts elevated, lymphocyte percentage(LYM%) significantly decreased; platelet volume(PCT) increased; glucose(Glu) decreased, blood urea(UN) decreased, and blood chloride(Cl) decreased. ConclusionThis study found that the FD, AD values of temporal lobe brain were associated with the peripheral blood test results, implying the mutual corroboration of the brain damage.

Neuroprotective efficacy of P7C3 compounds in primate hippocampus

There is a critical need for translating basic science discoveries into new therapeutics for patients suffering from difficult to treat neuropsychiatric and neurodegenerative conditions. Previously, a target-agnostic in vivo screen in mice identified P7C3 aminopropyl carbazole as capable of enhancing the net magnitude of postnatal neurogenesis by protecting young neurons from death. Subsequently, neuroprotective efficacy of P7C3 compounds in a broad spectrum of preclinical rodent models has also been observed. An important next step in translating this work to patients is to determine whether P7C3 compounds exhibit similar efficacy in primates. Adult male rhesus monkeys received daily oral P7C3-A20 or vehicle for 38 weeks. During weeks 2–11, monkeys received weekly injection of 5′-bromo-2-deoxyuridine (BrdU) to label newborn cells, the majority of which would normally die over the following 27 weeks. BrdU+ cells were quantified using unbiased stereology. Separately in mice, the proneurogenic efficacy of P7C3-A20 was compared to that of NSI-189, a proneurogenic drug currently in clinical trials for patients with major depression. Orally-administered P7C3-A20 provided sustained plasma exposure, was well-tolerated, and elevated the survival of hippocampal BrdU+ cells in nonhuman primates without adverse central or peripheral tissue effects. In mice, NSI-189 was shown to be pro-proliferative, and P7C3-A20 elevated the net magnitude of hippocampal neurogenesis to a greater degree than NSI-189 through its distinct mechanism of promoting neuronal survival. This pilot study provides evidence that P7C3-A20 safely protects neurons in nonhuman primates, suggesting that the neuroprotective efficacy of P7C3 compounds is likely to translate to humans as well.