We devised a method for collecting blood samples by remote control from socially housed nonhuman primates without disturbing their routine and without letting them know when samples were being drawn. This allowed measurement, in a social setting, of plasma catecholamines and other substances that may fluctuate rapidly in response to psychosocial and psychological stimuli. Venipuncture, removal of animals from their group, and changes in the animals' routines alter plasma catecholamine levels. Blood can be unobtrusively drawn from tethered animals, but the vulnerability of an exteriorized catheter limits opportunities for social contact and exercise. We protected the catheter by containing it within a backpack worn by the subjects. Three blood samples per subject were collected each session, so baseline levels could be compared to levels at two points during events. Behavior was recorded on videotapes, which were coded concurrently for posture/locomotion and for other activities the baboons engaged in, such as grooming and aggression [1, 2]. Radiotelemetry was used to measure heart rate and blood pressure [3]. An integrated picture of physiological correlates of rank in captive male baboons emerged from application of this design to three stable groups. Each group contained one dominant and one subordinate male and 1-2 females. Cortisol levels from samples collected in the compound during quiet times were more than twice as high in dominant males than in subordinates.

Heart rate, blood pressure, and plasma catecholamines did not differ by rank during quiet times or when baboons watched food treats being prepared. When food treats were in the compound, heart rate, blood pressure, and plasma nor-epinephrine were significantly higher in the dominant males. The same trend was seen during non-contact exposure to an intruder. Heart rate and blood pressure increases were higher and more sustained in the dominant males, who also had higher plasma norepinephrine and epinephrine levels. Remote-controlled blood draws, radiotelemetry, and behavior coding made it possible to determine baseline levels of the physiological variables in a social setting, and to study the impact of events on behavior and physiology in dominant and sub-ordinate baboons.

References

1. Astley, C.A.; Smith, O.A.; Ray, R.D.; Golanov, E.V.; Chesney, M.A.; Chalyan, V.G.; Taylor, D.J.; Bowden, D.M. (1991). Integrating behavior and cardiovascular responses: the code. American Journal of Physiology, 261, R172-R181.
2. Bentson, K.L. (1997). Hormonal, cardiovascular, and behavioral correlates of rank in male baboons during activities that occur in a social setting (Doctoral dissertation, University of Washington, 1997). Dissertation Abstracts International, 58, 9819206.
3. Spelman, F.A.; Astley, C.A.; Golanov, E.V.; Cupal, J.J.; Henkins, A.R.; Fonzo, E.; Susor, T.G.; McMorrow, G.; Bowden, D.M.; Smith, O.A. (1991). A system to acquire and record physiological and behavioral data remotely from nonhuman primates. IEEE Transactions on Biomedical Engineering, 38, 1175-1185.