Ronald R. Hutchinson

Possible errors in identification of squirrel monkeys (Saimiri sciureus) from different South American points of export.

We conducted karyological studies on one colony consisting of 12 Colombian and 34 Bolivian squirrel monkeys and a second colony of 47 monkeys imported into the United States between 1968 and 1974 through six importers. All animals in the first colony showed six acrocentric pairs of chromosomes. Bolivian monkeys were phenotypically distinguishable by their large size and coloration. In the second colony, 19 Peruvian, seven Colombian, five Bolivian and six Guyanan monkeys were correctly identified phenotypically and had five, six, six, and seven acrocentric pairs of chromosomes, respectively. Among Peruvian monkeys, 34.5% of the phenotypic classifications were in error.

Unique influences of ten drugs upon post-shock biting attack and pre-shock manual responding

Delivery of a fixed-time, response-independent electric tail shock to the squirrel monkey generated bites on a rubber hose immediately following shock and manual responses on a lever immediately preceding shock; two temporally and topographically different responses in a single organism in a single experimental session. d-Amphetamine, cocaine, and caffeine each had the effect of elevating both bite and lever press responses; nicotine, chlorpromazine, chlordiazepoxide, and diazepam each elevated lever press responding while depressing bite responding across a portion of the dosage range; phenobarbital, alcohol, and morphine had the effect of depressing both bite and lever press responses but lever pressing was selectively more depressed than biting. The results parallel previous research with these drugs on other measures of aggression and on other behavioral paradigms. The responses are contingency free so that the effect of a drug does not interact with response produced environmental consequences. The recording of two separate responses related to distinct emotional states from one organism in a single experimental session allows for the objective measurement of selective and differential drug effects.

The Effects of Cocaine on the Aggressive Behavior of Mice, Pigeons and Squirrel Monkeys

Historically cocaine, a central nervous stimulant, has been associated with subjective effects of euphoria, elevation of mood, indifference to pain, and increased vigor and muscular strength (Jaffe, 1965; Byck, 1974; Maurer and Vogel, 1967). Chronic use and high doses have been associated with irritability, anxiety, paranoid delusions and violence (Maurer and Vogel, 1967; Byck, 1974). Because cocaine shares many properties with the amphetamines and several studies have shown that amphetamine can potentiate aggression, there is supposition that cocaine may influence aggressive behavior but there is limited data on cocaine and violence to support this conclusively. Most information on the effects of cocaine on human behavior are anecdotal or clinical observations of addicts (Post, Kotin, and Goodwin, 1974). The experimental literature on the effects of cocaine is also sparse. Smith (1964) administered cocaine to pigeons on a fixed interval-fixed ratio (FI-FR) schedule for food. Responding on the FI schedule was increased at the higher doses of cocaine but FR rates were depressed. Hill, Bell and Wikler (1967) report no effect of cocaine administration (10 mg/kg s.c.) to rats on lever pressing for food on a conditioned suppression procedure. Kosman and Unna (1968) report increased endurance to swimming in dogs given cocaine and Simon, Sultan, Chermat and Boissier (1972) report hyperactivity and increased explorations in rats and mice at 2–4 mg/kg with stereotyped behavior occurring at 8 mg/kg. Kosman and Unna (1968) have reported that rats working on a water-reinforced task exhibited no tolerance to chronic administration of cocaine and performance returned to control levels upon withdrawal of the drug. Chronic administration of cocaine in humans does not produce physiological addiction (Jaffe, 1965; Post et al., 1974).

Nicotine ingestion reduces elevated blood pressures in rats and squirrel monkeys

Abstract Nicotine tartrate (0.002 -5.0 mg/kg/day) was added to the home cage drinking water of albino rat and squirrel monkey subjects for periods from 1 – 10 weeks. Rats received the drug for approximately 10 weeks and were then implanted with a chronic aortic cannula, allowed to recuperate, and blood pressure measured before and following exposure to a mild tail pinch procedure. All subjects receiving nicotine showed reduced blood pressure elevations to noxious stimulation compared to water control subjects, and these reductions were greater at higher drug doses. Squirrel monkeys exhibiting widely differing resting blood pressures were administered chronic dosages of nicotine. Subjects having high blood pressures showed dose-dependent blood pressure decreases, whereas subjects possessing low resting pressures demonstrated little or no pressure change during drug intake. A follow up study with high blood pressure subjects measured effects of progressive increases in drug followed by a return to drug-free water drinking solutions. Here again a dose-dependent decrease in both systolic and diastolic blood pressures were observed. Upon termination of drug intake, pressures rapidly increased to pre-drug levels. The results are concordant with previous studies demonstrating that oral nicotine ingestion causes reductions in aggresive behavior, and suggest that nicotine is selectively influential in altering the biological state of anger, decreasing both its behavioral and somatic components.