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Behavioral effects of thymoleptics in vervet monkeys (Cercopithecus aethiops).

Desmethylimipramine (DMI) exerts diverse quantitative effects on the gross behaviour of monkeys. Excitatory as well as sedative effects were observed, which varied according to the general animal temperament. Results resembling those obtained with DMI were observed using chlorimipramine and iprindole, although the effects of iprindole were less marked. Chlorimipramine also produced immobilization and postural change. The results are discussed in relation to behavioral effects of thymoleptics in humans, and the use of monkeys in preclinical testing of thymoleptic drugs is suggested.

Animals↗

Behavioral effects of low, acute doses of d-amphetamine on the dyadic interaction between mother and infant vervet monkeys (Cercopithecus aethiops) during the first six postnatal months.

Doses of d-amphetamine sulfate (0.1, 0.15, and 0.2 mg/kg body weight) were given to adult monkeys in mother-infant pairs. The fundamental parental care behavior pattern was disrupted and the mother became isolated in a socially withdrawn phase. She did not respond to the calling signals of the infant and showed behavior in which stereotyped self-grooming and/or 'staring' into space were predominant. The reactions of the infant to this amphetamine-induced behavior were different in the two experimental pairs. In group 1 the infant increased its approach--avoidance movements. In group 2 the infant sat very quietly and close in front of the mother. The mother from group 1 reacted to the increased approaches from its infant with active rejection. In both groups the mothers did not react with the typical ventral--ventral grasping to either the infants sitting close or to the social anxiety signals of the infants. In spite of differences in behavior changes induced by amphetamine, the main conclusion is that the mothers totally lost their normal and highly biologic significant interest in their infants.

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Regional specialization in pyramidal cell structure in the limbic cortex of the vervet monkey (Cercopithecus pygerythrus): an intracellular injection study of the anterior and posterior cingulate gyrus.

The pyramidal cell phenotype varies quite dramatically in structure among different cortical areas in the primate brain. Comparative studies in visual cortex, in particular, but also in sensorimotor and prefrontal cortex, reveal systematic trends for pyramidal cell specialization in functionally related cortical areas. Moreover, there are systematic differences in the extent of these trends between different primate species. Recently we demonstrated differences in pyramidal cell structure in the cingulate cortex of the macaque monkey; however, in the absence of other comparative data it remains unknown as to whether the neuronal phenotype differs in cingulate cortex between species. Here we extend the basis for comparison by studying the structure of the basal dendritic trees of layer III pyramidal cells in the posterior and anterior cingulate gyrus of the vervet monkey (Brodmann's areas 23 and 24, respectively). Cells were injected with Lucifer Yellow in flat-mounted cortical slices, and processed for a light-stable DAB reaction product. Size, branching pattern, and spine density of basal dendritic arbors were determined, and somal areas measured. As in the macaque monkey, we found that pyramidal cells in anterior cingulate gyrus (area 24) were more branched and more spinous than those in posterior cingulate gyrus (area 23). In addition, the extent of the difference in pyramidal cell structure between these two cortical regions was less in the vervet monkey than in the macaque monkey.

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Scanning electron microscope observations on the tubule content of freeze-fractured peripheral vervet monkey dentine (Cercopithecus pygerythrus).

Pulp tissue in the incisors was fixed in situ by perfusion. Cervical thirds of the tooth crowns were excised by sectioning the teeth transversely and cryofractured through the long axis of the tooth in a bucco-lingual mid-axial plane to expose the dentine from the pulp to the enamel-dentine junction. Specimens were freeze-dried and the fracture surfaces examined by scanning electron microscopy. Flattened tubular processes were noted protruding from the open ends of transversely fractured dentinal tubules in the outer third of the dentine. These structures were present in fractured tubules to within 20 microns of the enamel-dentine junction. These observations suggest that odontoblast processes traverse the full length of dentinal tubules.

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Effect of splinting on the mechanical and histological properties of the healing periodontal ligament in the vervet monkey (Cercopithecus aethiops).

Healing of the periodontal ligament (PDL) after extrusive luxation of two upper central incisors was evaluated when one tooth was splinted and the other left untreated. One millimetre thick, transverse sections of tooth, PDL and alveolar bone were examined in a materials testing machine. Load deformation curves were recorded and a number of mechanical properties were assessed. To eliminate the influence of differences in sizes and fibre arrangements, load values were reduced by the area and deformation values by the width of the PDL, and comparisons between splinted and non-splinted teeth were made at identical root levels 2 weeks after injury. Healing was also evaluated histologically at 1, 2, 3, 4 and 8 weeks after injury. There were no significant differences in mechanical and histological properties between splinted and non-splinted teeth, which suggests that splinting is of doubtful value in treatment of extrusive luxated teeth. The values for the mechanical properties of injured PDL had returned to 50-60% of those of uninjured PDL by 2 weeks after injury, indicating a rapid healing rate.

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Circadian rhythm of cholesterol-7alpha-hydroxylase and cortisol in the African green monkey (Cercopithecus aethiops).

Cholesterol-7alpha-hydroxylase in African green monkey liver had an apparent Km of 1.65-10(-4) M cholesterol and a pH optimum of 7.4. The amplitudes of the circadian maxima of enzyme activity and serum cortisol levels were significantly greater in vervets than in grivets. Fluctuations in enzyme activity and cortisol levels during the circadian cycle were positively correlated (r = 0.89). Enzyme activities and hormone levels were 2.7-fold lower over a 24-h period in the grivet than in the vervet. Cholesterol feeding reduced the enzyme activity by 40% and serum cortisol was reduced to 38% of control levels at the diurnal peak. Serum glucocorticoids may be important physiological regulators of cholesterol-7alpha-hydroxylase in non-human primates. The concentration of cortisol and its time of release appear to be factors in the hyperresponsive trait of grivets. Genetic differences between vervet and grivet races may account for differences in the amplitude and timing of the circadian rhythm of cholesterol-7alpha-hydroxylase activity possibly influenced by cortisol.

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Heterogeneity in the low density lipoproteins of cholesterol fed African green monkeys (Cercopithecus aethiops).

The low density lipoproteins of cholesterol-fed African green monkeys were isolated by either preparative ultracentrifugation or agarose column chromatography, then radioiodinated and fractionated by agarose column chromatography. A marked variation was noted in the specific radioactivity of the column fractions regardless of the method used to obtain low density lipoproteins. The radioactivity in each fraction migrated with the beta-globluins, but when the fractions were mixed with carrier plasma, alpha-migrating radioactivity was also detected which was associated with the apo-A-I and apo-C of the high density lipoproteins. The uptake of these apoproteins by the high density lipoproteins reduced the variation in specific radioactivity among the low density lipoprotein fractions. By successive injections of the various 125I-labeled low density lipoprotein fractions into the same recipient, it was also possible to compare the kinetic behavior of the fractions. Large and small low density lipoprotein particles were metabolized differently, indicating that the low density lipoproteins from cholesterol-fed African green monkeys are heterogeneous.

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