Conditioned taste aversion and motion sickness in cats and squirrel monkeys.

The relationship between vomiting and conditioned taste aversion was studied in intact cats and squirrel monkeys and in cats and squirrel monkeys in which the area postrema was ablated by thermal cautery. In cats conditioned 7-12 months after ablation of the area postrema, three successive treatments with xylazine failed to produce either vomiting or conditioned taste aversion to a novel fluid. Intact cats, however, vomited and formed a conditioned aversion.

Mechanics of vomiting: a minireview.

In a cineradiographic analysis of the vomiting reflex in response to i.v. administration of an emetic drug (lanatoside C, 12 mg/kg) in cats, it was shown that the vomiting act is preceded by cyclic periods of abnormal peristaltic activity of the small bowel and inhibition of gastric peristalsis.

The effect of area postrema lesions on hemodynamic responses to systemic methionine-enkephalin in conscious dogs.

In the intact conscious dog, intravenous methionine-enkephalin (ME) increases heart rate and mean arterial blood pressure (MAP). These hemodynamic responses are produced at lower dosages when ME is injected into the vertebral artery, but not the carotid artery, suggesting that ME receptors are localized in the vertebrobasilar artery circulation. The area postrema (AP), a circumventricular organ devoid of a functional blood-brain barrier, represents a likely site for these receptors.

Neurons numbers and dendritic extent in normal aging and Alzheimer's disease.

Evidence is reviewed regarding neuron numbers and dendritic extent in normal aging in rodent, monkey and human brain and in Alzheimer's disease (AD) in man. Neuron loss and change in dendritic extent appear to be regionally specific but not identical in rodents and primates. In AD there is excess neuron loss and dendritic regression in some but not all brain regions.

The anti-emetic properties of 1-sulpiride in a ground-based model of space motion sickness.

L-sulpiride, at a dose of 4 mg/kg, essentially abolished motion-induced emesis in a group of 6 squirrel monkeys undergoing horizontal rotation at 25 rpm, a terrestrial model of space motion sickness (SMS). Extrapyramidal side effects were not observed. In the absence of the drug, the usual emetic response returned.

Local brainstem glucose utilization in the squirrel monkey.

The 2-deoxy-D-[14C]-glucose method for the measurement of local cerebral glucose utilization (LCGU) in individual brain nuclei and regions has been applied to the squirrel monkey (Saimiri sciureus). The determinations were conducted in five conscious, lightly restrained adult, female, Colombian squirrel monkeys. Local glucose utilization in brainstem structures (LBGU) was highest in nuclei involved in auditory and vestibular functions and in some nuclei involved in general motor activity.

Effect of macular ablation on frequency and latency of motion-induced emesis in the squirrel monkey.

Three previously motion-emetic sensitive squirrel monkeys were rendered refractory to a standard motion-emetic regimen by a two-stage utriculosacculectomy procedure which preserved the cristae ampullares of semicircular canals. Three non-operated control squirrel monkeys tested on the same motion-emetic regimen time schedule as the operated animals remained motion-emetic sensitive with regard to incidence, frequency, and latency of motion-induced emetic responses. Following a sham surgical procedure (stapedectomy) performed on two of the latter animals and one additional new animal, the emetic incidence decreased from 100% to 89%, but the frequency and latency were not altered significantly.

Lipofuscin in retinal pigment epithelium of rhesus monkey: lack of diminution with centrophenoxine treatment.

An experiment was performed to test the ability of Centrophenoxine to reduce the amount of lipofuscin (age pigment) in the retinal pigment epithelium (RPE) of aged rhesus monkeys. Centrophenoxine is reputed to have this action in neurons of lower mammals. Quantitative electron microscopic analysis was performed on sections from the perifovea of ten rhesus monkeys, all approximately 20 years of age.

Choline acetyltransferase and acetylcholinesterase activities in neocortex and hippocampus of squirrel monkey (Saimiri sciureus).

The activities of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) were measured in five neocortical regions and in the hippocampal formation of one hemisphere in eight 30-day-old squirrel monkeys. Enzyme levels in the hippocampal formation (hippocampus, dentate gyrus, and subiculum) were higher than in any neocortical region. Within neocortex, ChAT activity was highest in superior temporal and precentral regions, intermediate in prefrontal and postcentral regions, and lowest in occipital cortex.

Muscarinic cholinergic receptors in area postrema and brainstem areas regulating emesis.

Central cholinergic pathways modulate both the perception of excessive motion stimuli and the expression of motion sickness symptoms, such as nausea and vomiting. Specific brainstem areas which mediate motion-induced emesis include the area postrema (AP), vagal nuclear complex (VNC), reticular formation (RF) at the site of the vomiting center, and the vestibular complex (VC). In this report, histological studies indicated the cellular organization of brainstem structures mediating emesis was similar in bovine and squirrel monkey brain.

The structure of the mammalian area postrema.

The area postrema in mammals other than rodents and lagomorphs is a bilateral mound of gelatinous-appearing tissue that protrudes into the caudal fourth ventricle on either side of the obex. In rodents and lagomorphs it is a single midline structure at the apex of the calamus scriptorius. The vasculature is derived mainly from the posterior inferior cerebellar arteries and consists mainly of sinusoidal capillaries.

Motion-induced alterations in 2-deoxyglucose uptake in brainstem nuclei of squirrel monkeys: autoradiographic and liquid scintillation studies.

Each of 8 young adult female squirrel monkeys were injected via a femoral vein cannula with 167 microCi/100 g body weight of 2-(1,2-3H)-deoxy-D-glucose (2-DG) (New England Nuclear, 37.3 Ci/mmol) in 0.5 ml sterile saline.

Prenatal ionizing irradiaton and early postnatal growth of Colombian and Bolivian squirrel monkeys (Saimiri sciureus).

Fetal squirrel monkeys of Bolivian and Colombian origin were exposed to 100 rad cobalt-60 radiation in utero and carried to term by the dams. Body weight, head circumference, crown-rump length, and food intake were measured during the first 28 postnatal days. Significant subspecies differences were noted in both mothers and offspring, the Colombian squirrel monkeys being generally larger than the Bolivians.

Effect of prenatal ionizing radiation on the visual cortex and hippocampus of newborn squirrel monkeys.

Five squirrel monkeys were exposed to 200 rads whole-body ionizing irradiation (60Co) at 0.4 rads per second on approximately the seventy-fifth day of gestation, and six squirrel monkeys were sham-irradiated. The mean cortical depth and the mean number of neurons per mm3 in the visual cortex was less in irradiated animals than in controls, but the differences were not statistically significant.

Motion sickness in the squirrel monkey.

Because it is of the same taxonomic order as man, the squirrel monkey has been introduced as a nonhuman primate model for the study of such aspects of motion and space sickness as susceptibility, prevention, treatment, and neural mechanisms. In this study on susceptibility, the specific aims were to examine the effects of combined vertical rotation and horizontal acceleration, phenotype, sex, visual cues, morning and afternoon testing, and repeated test exposures on incidence, frequency, and latency of emetic responses. The highest emetic incidence of 89%, with an emetic frequency of 2.

Localization of cellular changes within multimodal sensory regions in aged monkey brain: possible implications for age-related cognitive loss.

Young (4 to 7 years) and aged (18 to 28 years) rhesus monkeys were sacrificed and various neuromorphometric analyses performed to determine age differences in gross topography, cell population and patterns of cellular degeneration. Two brain regions implicated for their role in age-related cognitive disturbances, the hippocampus and the gyri bordering the principal sulcus in the frontal cortex were selected for these comparisons. Reliable morphometric differences between age groups were observed in both neural areas.

Motion sickness-induced food aversions in the squirrel monkey.

Conditioned aversions to colored, flavored water were established in Squirrel monkeys (Saimiri sciureus) by following consumption with 90 min of simultaneous rotational and vertical stimulation. The experimental group (N = 13) drank significantly less of the green, almond-flavored test solution than did the control group (N = 14) during three post-treatment preference testing days. Individual differences were noted in that two experimental monkeys readily drank the test solution after rotational stimulation.

The growth and development of the squirrel monkey (Saimiri Sciureus).

Squirrel monkeys of 2 subspecies, Bolivian and Colombian, were removed from their mothers on the day of birth and nursery reared for up to 2 years of age. Infants were tested weekly for 12 weeks, then monthly for 1 year, and at 2 years of age. Tests included morphology (body weight, crown-rump length, and head measurements), behavior (reflexes, activity, reaction to the surrogate), and physiology (heart rate, respiratory rate, temperature and optokinetic nystagmus).

Comparative normal levels of serum triiodothyronine and thyroxine in nonhuman primates.

Normative values were obtained for triiodothyronine and thyroxine from four species of Old World primate (chimpanzees, rhesus monkeys, African green monkeys and talopoin monkeys) and a single species of New World primate (squirrel monkeys) represented by two subspecies, Colombian and Bolivian. The Bolivian squirrel monkeys exhibited the lowest values for both triiodothyronine and thyroxine. Male talapoins had the highest levels of thyroxine.