System Of Rhesus Monkeys Research Articles

α-Synuclein Expression is Preserved in Substantia Nigra Gabaergic Fibers of Young and Aged Neurotoxin-Treated Rhesus Monkeys

Background: α-Synuclein (α-syn) is a small presynaptic protein ubiquitously distributed in the central and peripheral nervous system. In normal conditions α-syn is found in soluble form, while in Parkinson’s disease (PD) it becomes phosphorylated, aggregates, and combines with other proteins to form Lewy bodies. Objective: To study in non-human primates whether α-syn expression is affected by age and neurotoxin challenge. Methods: Young adult (n=5, 5-10 years old) and aged (n=4, 23-25 years old) rhesus monkeys received a single unilateral carotid artery injection MPTP. Four untreated rhesus monkeys (n=3, 5-8 years old; n=1, 24 years old) were used as controls. Three months post-MPTP the animals were necropsied by transcardiac perfusion, their brains extracted and processed with immunohistochemical methods. Results: Quantification of tyrosine hydroxylase (TH)-ir nigral neurons showed a significant and similar decrease in the side ipsilateral to MPTP administration in young and old animals. Optical density of TH-ir in the striatum presented a 60-70% loss compared to the contralateral side. α-Syn immune-reactivity was present in both ipsiand contralateral MPTP-treated nigra and striatum, mostly in fibers; its intracellular distribution was not affected by age. Comparison of α-syn-ir between MPTP-treated young and aged monkeys revealed significantly higher optical density for both the ipsi- and contralateral caudate and substantia nigra in the aged animals. TH and α-syn immunofluorescence confirmed the loss of nigral TH-positive dopaminergic neurons in the MPTP-treated side of intoxicated animals, but bilateral α-syn expression. Colabeling of GAD67 and α-syn immunofluorescence showed that α-syn expression was mainly present in GABAergic fibers. Conclusion: Our results demonstrate that three months post MPTP α-syn expression in the substantia nigra is mainly present in GABAergic fibers. It also shows that α-syn expression in the nigrostriatal system of rhesus monkeys increases with age, but not after neurotoxin-induced dopaminergic nigral cell loss.

Myeloid-lymphoid ontogeny in the rhesus monkey (Macaca mulatta).

Establishment of a functional immune system has important implications for health and disease, yet questions remain regarding the mechanism, location, and timing of development of myeloid and lymphoid cell compartments. The goal of this study was to characterize the ontogeny of the myeloid-lymphoid system in rhesus monkeys to enhance current knowledge of the developmental sequence of B-cell (CD20, CD79), T-cell (CD3, CD4, CD8, FoxP3), dendritic cell (CD205), and macrophage (CD68) lineages in the fetus and infant. Immunohistochemical assessments addressed the temporal and spatial expression of select phenotypic markers in the developing liver, thymus, spleen, lymph nodes, gut-associated lymphoid tissue (GALT), and bone marrow with antibodies known to cross-react with rhesus cells. CD3 was the earliest lymphoid marker identified in the first trimester thymus and, to a lesser extent, in the spleen. T-cell markers were also expressed midgestation on cells of the liver, spleen, thymus, and in Peyer's patches of the small and large intestine, and where CCR5 expression was noted. A myeloid marker, CD68, was found on hepatic cells near blood islands in the late first trimester. B-cell markers were observed mid-second trimester in the liver, spleen, thymus, lymph nodes, bone marrow spaces, and occasionally in GALT. By the late third trimester and postnatally, secondary follicles with germinal centers were present in the thymus, spleen, and lymph nodes. These results suggest that immune ontogeny in monkeys is similar in temporal and anatomical sequence when compared to humans, providing important insights for translational studies.

Preclinical Deposition of Pathological Prion Protein in Muscle of Experimentally Infected Primates

Prion diseases are transmissible fatal neurodegenerative disorders affecting humans and animals. A central step in disease progression is the accumulation of a misfolded form (PrPSc) of the host encoded prion protein (PrPC) in neuronal and non-neuronal tissues. The involvement of peripheral tissues in preclinical states increases the risk of accidental transmission. On the other hand, detection of PrPSc in non-neuronal easy-accessible compartments such as muscle may offer a novel diagnostic tool. Primate models have proven invaluable to investigate prion diseases. We have studied the deposition of PrPSc in muscle and central nervous system of rhesus monkeys challenged with sporadic Creutzfeldt-Jakob disease (sCJD), variant CJD (vCJD) and bovine spongiform encephalopathy (BSE) in preclinical and clinical stage using biochemical and morphological methods. Here, we show the preclinical presence of PrPSc in muscle and central nervous system of rhesus monkeys experimentally infected with vCJD.

Autonomic drugs and the accommodative system in rhesus monkeys

Accommodation and pupil constriction result from parasympathetic stimulation from the Edinger–Westphal (EW) nucleus of the midbrain resulting in release of acetylcholine at the neuromuscular junctions of the ciliary muscle and iris. Cholinergic and adrenergic drugs can be applied topically to evaluate the effects on the pupil and accommodative system without input from the EW nucleus. This study is directed at characterizing how topical low dose echothiophate, an anti-cholinesterase inhibitor (i.e., an indirect cholinergic agonist), epinephrine, an adrenergic agonist, and timolol maleate, a beta adrenergic antagonist, affect pupil diameter, resting refraction and accommodative amplitude and dynamics in rhesus monkeys. The effects of 0.015% echothiophate, 2% epinephrine, 0.5% timolol maleate and saline on pupil diameter and resting refraction were measured in one eye each of four normal rhesus monkeys for 60–90 min following topical instillation. Pupil diameter was measured with infrared videography and refraction was measured with a Hartinger coincidence refractometer. Effects on static and dynamic EW stimulated accommodation were studied in three iridectomized monkeys (ages 5, 6 and 12 years) with permanent indwelling stimulating electrodes in the EW nucleus. Dynamic accommodative responses were measured with infrared photorefraction for increasing current amplitudes before and during the course of action of the pharmacological agents. Echothiophate caused a significant decrease in pupil diameter of 3.07 ± 0.65 mm (mean ± SEM, p < 0.01), and a myopic shift in resting refraction of 1.30 ± 0.39 D ( p < 0.05) 90 min after instillation. Epinephrine caused a 2.76 ± 0.38 mm ( p < 0.01) increase in pupil diameter with no change in resting refraction 60 min after instillation. Timolol maleate resulted in no significant change in either pupil diameter or resting refraction 60 min after instillation. There was no significant change in maximum EW stimulated accommodative amplitude after any agent tested. The amplitude vs. peak velocity relationship for accommodation was significantly different after echothiophate and timolol maleate, and for disaccommodation after echothiophate, epinephrine and timolol maleate. In conclusion, when tested objectively in anesthetized monkeys, epinephrine and timolol maleate did not alter resting refraction or accommodative amplitude, but did have small, significant affects on accommodative dynamics. This suggests that there is an adrenergic component to the accommodative system. Low dose echothiophate had significant effects on pupil diameter and resting refraction, with only small effects on the dynamics of the accommodative response.

Gamma delta T cells in rhesus monkeys and their response to simian immunodeficiency virus (SIV) infection.

Recent reports of the increase in peripheral blood gamma delta T cells in HIV+ patients prompted us to examine the gamma delta T cell system in rhesus monkeys (Macaca mulatta) and the responses of these cells to SIV infection. Our results reveal differences in the gamma delta T cell subset composition and their expression of CD8 in the peripheral blood of monkeys and humans. The outgrowth of simian gamma delta T cells in response to Daudi cells is similar to that in humans, but the exposure to IL-2 stimulates preferentially the simian V delta 1 subset rather than the V gamma 9/V delta 2 subset as found in humans. Upon SIV infection of the monkeys, we observed a transient increase of the percentage of total gamma delta T cell and the V gamma 9 subset. gamma delta T cells from infected animals also express more activation markers such as CD69, CD44 and the memory marker CD45RO. However, they respond to a lesser degree to Daudi or IL-2 stimulation in the outgrowth experiments compared with uninfected animals, although the subset composition of total gamma delta T cells is similar in infected and uninfected animals. The results clearly indicate that gamma delta T cells in rhesus monkeys are influenced by SIV infection. The detailed analysis of the gamma delta T cell response to SIV infection can serve as a model for understanding human gamma delta T cell responses to HIV infections.

Behavioral Pharmacology of the μ/δ Opioid Glycopeptide MMP2200 in Rhesus Monkeys

H(2)N-Tyr-D-Thr-Gly-Phe-Leu-Ser-(O-beta-D-lactose)-CONH(2) (MMP2200) is a novel glycopeptide opioid agonist with similar affinities for mu and delta receptors. Glycosylation promoted brain penetration and production of centrally mediated behavioral effects in mice; however, it is unknown whether the magnitude of enhanced brain penetration is sufficient to permit central mediation of drug effects and production of synergistic mu/delta antinociceptive interactions after systemic administration in primates. To address this issue, the present study compared the effects of MMP2200 and the mu-agonist morphine in four behavioral procedures in rhesus monkeys. In an assay of thermal nociception, morphine (1.0-5.6 mg/kg) produced dose-dependent antinociception, whereas MMP2200 (10-56 mg/kg) was ineffective. In an assay of capsaicin-induced thermal allodynia, both morphine (0.01-1.0 mg/kg) and MMP2200 (0.032-3.2 mg/kg) produced dose-dependent antiallodynic effects. MMP2200-induced antiallodynia was blocked by the moderately mu-selective antagonist naltrexone (0.01 mg/kg), the delta-selective antagonist naltrindole (1.0 mg/kg), and the peripherally selective opioid antagonist quaternary naltrexone (0.32 mg/kg). In an assay of schedule-controlled behavior, both morphine (0.01-1.0 mg/kg) and MMP2200 (10-56 mg/kg) decreased response rates. Morphine effects were antagonized by naltrexone (0.001-0.01 mg/kg); however, the effects of MMP2200 were not antagonized by either naltrexone (0.01 mg/kg) or naltrindole (1.0 mg/kg). In an assay of drug self-administration, morphine (0.0032-0.32 mg/kg/injection) produced reinforcing effects, whereas MMP2200 (0.032-0.32 mg/kg/injection) did not. These results suggest that systemically administered MMP2200 acted as a peripheral, mu/delta-opioid agonist with limited distribution to the central nervous system in rhesus monkeys. These results also suggest the existence of species differences in the pharmacokinetics and brain penetration of glycopeptides.

Linking emotion to the social brain

In 2006, research on the neurotransmitter serotonin and its transporter protein (5‐HTT) in the synaptic gap celebrated a series of anniversaries. Forty‐five years earlier, presynaptic neurotransmitter uptake was discovered (Hertting & Axelrod, 1961). Two decades later, 5‐HTT was first linked to depression (Langer et al , 1981), shortly after its identification as a target of antidepressant drugs (Raisman et al , 1979). The sequence of the transporter gene from rats was published 10 years after that (Blakely et al , 1991), which initiated an avalanche of molecular genetic studies on the regulation of emotionality. This research culminated in two reports revealing an association between variations of the 5‐HTT gene ( 5‐HTT and SLC6A4 ) and anxiety‐related traits as well as depression (Collier et al , 1996; Lesch et al , 1996). Since then, clinical studies have further supported the link between variants of 5‐HTT and disorders in the regulation of emotion. Although modest effect sizes—typical of non‐Mendelian traits—polygenic patterns of inheritance, epistatic and epigenetic interactions, and heterogeneity between studies confounded the results, 5‐HTT comprises a model molecule for studying gene–environment interactions in cognitive and psychiatric neuroscience. The demonstration in rhesus macaques that stress early in life uniquely reinforces links between variations of 5‐HTT , behaviour and psychopathology seems to herald in a new era of behavioural genetics. Moreover, the discovery that 5‐HTT is a susceptibility gene for depression is a first step towards explaining the molecular dimensions of personality and behaviour, identifying physiological pathways that lead to other disorders of cognitive function and emotion, and analysing the interactive effects of genes and environment in the development of disease. On the heels of these results from behavioural genetics, novel approaches including neurophysiology, neuropsychology and functional neuroimaging, as well as the inclusion of other phenotypes (such as higher cognitive functions, communication skills, social competence and longevity), have …

Aspiration lesions of the amygdala disrupt the rhinal corticothalamic projection system in rhesus monkeys.

In macaque monkeys, aspiration but not excitotoxic lesions of the medial temporal lobe limbic structures, the amygdala and hippocampus, produce a severe impairment in visual recognition memory. Furthermore, certain ventromedial cortical regions, namely the rhinal (i.e., entorhinal and perirhinal) cortex, are now known to be critical for visual recognition memory. Because the route taken by temporal cortical efferent fibers, especially perirhinal efferents, passes nearby the amygdala, it is possible that inadvertent damage to these fibers is produced by the aspirative but not the excitotoxic process, thereby accounting at least in part for the different behavioral outcomes of the two types of lesion. To test this idea, we assessed the integrity of the rhinal corticothalamic projection system after aspiration lesions of the amygdala. Three rhesus monkeys with unilateral amygdala removals received bilaterally symmetrical injections of a retrograde fluorescent tracer into the medial portion of the mediodorsal nucleus of the thalamus. Retrogradely labeled cells were identified using conventional fluorescence microscopy techniques. In all three cases, the rhinal cortex of the intact hemispheres contained moderate numbers of retrogradely labeled cells. By contrast, the rhinal cortex of the amygdalectomized hemispheres consistently contained few retrogradely labeled cells, and a direct comparison of the two hemispheres showed this difference to be statistically significant. A similar asymmetric pattern was observed for area TE but not for the cortex lining the dorsal bank of the superior temporal sulcus, nor for the rostral cingulate motor area, which was examined as a control. The results indicate that aspiration lesions of the amygdala not only remove the cell bodies of the amygdala, as intended, but also inadvertently disrupt projection fibers arising from cells in the rhinal cortex and area TE that pass nearby or through the amygdala en route to the thalamus. Behavioral studies examining the effects of aspiration lesions of the amygdala in nonhuman primates need to take these findings into consideration.

Effect of anti-relapse antimalarial compound CDRI 80/53 and primaquine on hepatic mixed function oxidase system of rhesus monkey

A potential anti-relapse antimalarial compound CDRI 80/53 [N1-(3-acetyl-4-5-dihydro-2-furanyl)-N4-(6-methoxy-8-quinolinyl)1,4- pentanediamine] at 7.5 mg/kg body weight and primaquine at 6.0 mg/kg body weight did not cause any significant change in the status of hepatic microsomal mixed function oxidase system of rhesus monkeys, when given orally for 7 days. Further, the extension of the treatment at the same dossier up to 21 days resulted in impairment of the different indices of the MFO system. The compound CDRI 80/53 inhibited cytochrome P-450, aminopyrine-N-demethylase, aniline and benzo(a)pyrene hydroxylases, cytochrome b5 and haem levels by 17, 11, 58, 0, 36 and 35% whereas the inhibition caused by primaquine was 34, 40, 72, 54, 39 and 38% respectively, establishing that the cytochrome P-450 dependent mono-oxygenase system of monkey liver was comparatively less suppressed by compound CDRI 80/53. The cessation of the compound/drug treatment resulted in almost complete reversal of all the MFO activities to normal in a period of about 6 weeks.

Further characterization of the G blood group system of rhesus monkeys.

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

The behaviour of Sabin attenuated poliovirus strains in the central nervous system of rhesus monkeys

The three Sabin attenuated strains of polioviruses (passage level SO + 2 or SO + 3) were injected into the lumbar enlargement and thalamus of rhesus monkeys. Following intraspinal injection, there was no significant difference in the neuronal response elicited by the three serotypes in the lumbar region. The production of neuronal lesions constituted the sole indicator of virus neurovirulence. The neuronal response in the cervical cord and brain was maximal with type 3, minimal with type 1 and intermediate with type 2. The incidence of clinical poliomyelitis was more or less similar with type 1 and type 2 and nil with type 3. The intracerebrally injected monkeys did not show any intertypic differences in the neuronal response in the thalamus, spinal cord or brain stem. There was no incidence of clinical poliomyelitis either. It has been recommended that during the neurovirulence testing of any oral poliovaccine bulk suspension a homotypic reference preparation should be used in the intraspinal test and preferably in the intracerebral test.

Prenatal development of the visual system in rhesus monkey.

Autoradiographic evidence from juvenile rhesus monkeys that had been exposed to a pulse of [1 *3H]thymidine at different embryonic (E) and early postnatal (P) days indicates that all neurons which compose the visual system of this primate have been generated two months before birth. The first retinal ganglion cells (RGG) are generated around E30 preceding by a few days the onset of genesis of neurones destined for the dorsal lateral geniculate body (LGd) and superior colliculus (SC) both of which begin at E36. Production of neurons destined for the primary visual cortex (area 17) begins at approximately E43 and ends by E l02. Neurons destined for layer IV, the major target of axons from the LGd, are generated between E70 and E85. The prenatal development of visual connections was studied by the autoradiographic method of anterograde axoplasmic transport in foetuses killed 14 days after unilateral eye injection of a mixture of [ 3 H]proline and [ 3 H]fucose. Initially, in the LGd and in the SC projections from both eyes overlap. Segregation of the axons and/or terminals from the two eyes occurs in the LGd and SC during the middle period of gestation. Transneuronal transport of tritium shows that although LGd axons form the optic radiation before E78, these fibres do not yet enter the developing cortical plate at this foetal age. During the second half of gestation, geniculocortical axons carrying input from each eye invade the cortex but are not yet segregated into ocular dominance columns. Rather, grains are distributed uniformly over the entire layer IV at E l24. Three weeks before birth, at E l44, segregation of afferents into sublayers IVA and I VC is apparent, and the first hint of ocular dominance columns is displayed by slight differences in grain counts in alternating areas of layer IV. These results show that all neurons in the primate visual system have been generated, reached their final positions and formed their basic connections subserving ocular dominance before birth, i.e. before visual experience. In the SC and LGD, monocular segregation is well established during the middle period of gestation, whereas in the cortex it has begun, but is not fully developed at birth.

Plasmocid Encephalopathy in the Rhesus Monkey: A Study of Selective Vulnerability

The effects of plasmocid (8-diethylaminopropylamino-6-methoxyquinoline) on the central nervous system of rhesus monkeys were studied by electron and correlative light microscopy. Light microscopic studies showed neuronal vacuolar lesions distributed selectively in the diencephalon and brain stem. In the affected nuclei, principally III, IV, VI and VIII, the brunt of the damage was consistently borne by large multipolar neurons. The cerebral and cerebellar cortices were normal. Electron microscopy showed the earliest effects to be an abnormality of neuronal mitochondria, which were enormously increased in number with incompletely formed transverse inner cristae. Later stages of degeneration showed dissolution of mitochondrial contents so that only their outer membranes remained. Neuroglia were morphologically normal, as were synapses in contact with the altered neurons. Neurons in the most advanced stage of degeneration exhibited complete destruction of cytoplasmic contents and disruption of the cell membrane with crenated nuclei remaining. The ultrastructural data confirm the highly selective vulnerability of brain stem nuclei to plasmocid and suggests that the primary effect of the drug is on neuronal mitochondria.

The lymphatic system in rhesus monkeys (Macaca mulatta) outlined by lower limb lymphography.

The lymphatic system in rhesus monkeys (Macaca mulatta) outlined by lower limb lymphography.

The I blood group system of rhesus monkeys.

The I blood group system of rhesus monkeys.

Individual different response to drugs: Characterisation of an INH-acetylating system in rhesus monkeys

The biochemical properties of an INH acetylating enzyme protein of liver homogenates from rhesus monkeys were studied. The enzyme was purified about 250-fold. Studies of substrate specificity to aliphatic and aromatic compounds as well as comparison of the structure of some competitive inhibitors were performed. Serotonin is acetylated to acetyl serotonin with high affinity to the INH acetylating enzyme. Enzyme preparations from so-called rapid and slow acetylating animals show different specific activities, but similar properties regarding purification values, K m 0-values of INH, inhibitor constants of some aromatic compounds. Comparing arylamine acetylase of pigeon liver with the acetylating system of rhesus-liver, we stated characteristic differences.

STUDIES OF THE VIRULENCE OF LANGAT VIRUS PROPAGATED IN CHICK EMBRYO OR HAMSTER KIDNEY TISSUE CULTURES.

Summary When the eighth mouse brain passage of Langat virus was serially propagated in chick embryo tissue cultures, about 70% of the plaquepurified clones prepared from the 12th or 20th passages showed an increased virulence for mice as measured by peripheral infectivity. Such virus clones also caused more severe lesions of the central nervous system in rhesus monkeys inoculated intracerebrally than the virus did before chick embryo tissue culture passage. A serologic comparison of the original Langat virus present in the eighth brain suspension with the viruses present in the 12th or 20th chick embryo tissue cultures, as well as studies of control uninfected tissue culture fluids, showed that the virus present in these chick embryo tissue cultures was Langat virus. Therefore, this increase in virulence was due to Langat virus and not to some latent virus present in the tissue cultures or to a virus picked up by laboratory contamination. When the same original infected mouse brain suspension containing Langat virus was passed in hamster kidney tissue cultures only 3% of the plaque-purified isolates showed an increase in virulence. These results were obtained in a study of 100 plaque-purified isolates grown in chick embryo tissue cultures, 10 isolates being selected from each of 10 tissue culture tubes, and 100 plaque-purified isolates grown in hamster kidney tissue cultures, both types of virus clones being picked in a similar manner. Further studies on the attenuated TP-21-9 isolate of Langat virus were reported. Of 29 monkeys that were inoculated intracerebrally with high doses of this isolate only one showed evidence of mild lesions in the brain. Histologic examination revealed mild to moderate lesions in the brains of 24 of 28 monkeys inoculated with similar concentrations of the original parent virus.

Observation of infant monkeys by female monkeys.

This paper reports an exploratory study attempting to isolace one aspect of the maternal affectional system of rhesus monkeys (Harlow, 1960). Specifically, the visual incentive value of infant monkeys was measured in nulliparous adults and in multiparous animals before and after parturition. METHOD Sz~b jects Fifteen mature female rhesus monkeys from the colony maintained at the Wisconsin Primate Laboratory served as Ss. There were three groups of five each. Gravid multiparous Ss, Numbers R-65, 341, R-15, 313, and G-7, comprised the experimental group, Group E. They were started in the apparatus approximately three weeks before their expected parcuricion, with actual days prior to delivery being 14 to 37 (mean, 22). A multiparous concrol group, Group M, contained nonpregnant mulriparous Ss, Numbers R-55, R-69, 302, 202, and 346, which had given birth rwo to four months prior. A second control group, N, consisted of nulliparous Ss, Numbers 376, 379, 389, 393, and 437, each showing consistent ovulatory cycles. Apparatus A modified visual exploration apparatus was constructed by removing the backs from two smaller single-door chambers of the type employed by Butler and Harlow (1954) and juxtaposing the open ends to form a 5-ft. by 1%-ft. rectangular chamber with a height of 25 in. This box rested on a 3-ft.-high platform. At opposite ends of the chamber and covering che openings that served as windows were two hinged, opaque doors 3% in. by 4 in., equipped with light springs. Opening a door 2 in. simultaneously activated an electronic counter and a Standard Electric timer which ran as long as S held the door open. Only one door could be opened in a 15-sec. period, which started with che automatic withdrawal of a metal shield in front of each door and ended wich repositioning of the shields for a 15-sec. intertrial period. Illumination in the chamber was provided by a 60-w shielded light bulb fixed at each end above a 7-in.-diameter opening covered wich %-in. translucent plascic. Positioned at each end 15 in. distant from the chamber were two identical

Immunization Against Yellow Fever with a Consideration of the Effects of a Virulent Neurotropic Strain on the Central Nervous System of Monkeys

Summary The effect of small amounts of a virulent strain of neurotropic yellow fever on the central nervous system of rhesus monkeys (Macaca mulatta) was tested by direct injection into the cerebrum, into the great cistern, and also by subcutaneous injection with gross traumatization of the brain. Some animals developed a fatal encephalitis, some developed immune bodies in their serum and some remained normal with the probability that the inoculum for at least part of these contained no virus. There were no recoveries among the monkeys in which definite signs of encephalitis appeared. Accidents of vaccination in man have occurred in any form of technique in which living virus is employed. Thus far, the patients have shown symptoms of meningitis, encephalitis or myelitis followed by complete recovery without sequellae.