Adams, M. R., Kaplan, J. R., Manuck, S. B. et al. 1988. Persistent sympathetic nervous system arousal associated with tethering in cynomolgus macaques. Laboratory Animal Science 38, 279-282.

Persistent elevation in heart rate associated with tethering appears to be the result of a persistent influence of the sympathetic nervous system on cardiac function. .... Other organs and systems, e.g., pituitary-gonadal system, also may be affected.