, Volume 103, Issue 2, pp 268–270

Effects of shock intensity on observed tolerance to decreased avoidance responding by clonidine


  • James B. Smith
    • Worcester Foundation for Experimental Biology
Original Investigations

DOI: 10.1007/BF02244215

Cite this article as:
Smith, J.B. Psychopharmacology (1991) 103: 268. doi:10.1007/BF02244215


Interruption of a photobeam by rats was maintained under a Sidman avoidance schedule, and moderate response rates were maintained at low frequencies of electrical stimulation. After acute injections of clonidine, responding decreased, and frequency of electric stimulation increased, in a dose-dependent manner. At a lower intensity of electric stimulation, response-suppressive effects of clonidine did not diminish for up to 40 sessions with daily administration of clonidine. At a higher stimulus intensity, however, response-suppressive effects of clonidine diminished within 15 sessions, and stimulus frequency was at control level after 40 sessions with daily administration of clonidine. Behavioral consequences altered the effects of chronic clonidine so that tolerance was observed at a higher, but not a lower, intensity of electric stimulation.

Key words

Clonidine Behavioral tolerance Sidman avoidance Shock intensity Rats

Copyright information

© Springer-Verlag 1991