Two-component arterial blood pressure conditional response in rat
Tóm tắt
The objective of these experiments was to quantify the pattern of change in arterial blood pressure (BP) during a discriminative aversive classical conditioning paradigm in rat using a new “high resolution” computer analysis. Sprague-Dawley rats (n=5) were restrained in a soft, conical cloth pouch and conditioned using a 6 sec. pulsed tone (CS+) followed by a 0.5 sec. tail shock; a steady tone, never followed by shock, served as a CS-. BP peaked at 16.4±6.5 mm Hg (mean±SD) above control at 1.5±0.1 sec. after onset of CS+. This “first component” (“C1”) also occurred during CS- (12.1±3.8 mm Hg), although the magnitudes of the two were significantly (p<0.05) different. Another group of rats (n=8) was treated identically except the tones were 15 seconds long. The conditional BP response consisted of two components. C1 was reminiscent of that seen using the short tone: for CS+ a peak of 13.6±5.6 mm Hg at 1.5 sec. or, for CS-, of 10.0±4.3 at 1.3 sec. (p<0.05). In CS+ trials BP peaked again (“C2,” 7.4±2.5 mm Hg) at 8.3±1.2 sec. There was no statistically significant C2 for CS- trials, clearly demonstrating discrimination between tones. The unconditional BP response in both groups consisted of two large, closely spaced peaks in BP. Respiration was recorded in 3 additional rats. After shock delivery these subjects often showed a sudden shift between (1) a regular respiratory pattern with moderate chest excursion and (2) apneic episodes interspersed with single, deep breaths. This latter pattern was associated with large, low frequency fluctuations in BP. Continued development of the rat conditioning paradigm is especially warranted because of the ability to record sympathetic nerve activity in intact, awake subjects and the large number of readily available genetic strains, which model human pathological states.
Tài liệu tham khảo
Billman, G.E., & Randall, D.C. (1981). Mechanisms mediating the coronary vascular response to behavioral stress in dog.Circulation Research, 48: 214–223.
Brown, D.R., Brown, L.V., Patwardhan, A., & Randall, D.C. (1992). Interaction between sympathetic nerve activity and arterial pressure in conscious and anesthetized rat.Society Neuroscience Abstracts, 18: 1182.
Brown, D.R., Randall, D.C., & Raisch, R.M. (1990). A temporally detailed re-analysis of the conditional heart rate response in dog.Physiology & Behavior, 48: 333–337.
Cohen, D.C., & Randall, D.C. (1984). Classical conditioning of cardiovascular responses.Annual Review Physiology, 46: 187–197.
Dworkin, B.R., & Dworkin, S. (1990). Learning of Physiological Responses. 1. Habituation, Sensitization, and Classical Conditioning.Behavioral Neuroscience, 104: 298–319.
Hatton, D.C., Buchholz, R.A., & Fitzgerald, R.D. (1981). Autonomic control of heart rate and blood pressure in spontaneously hypertensive rats during aversive classical conditioning.Journal of Comparative Physiology Psychology, 95: 978–990.
Hatton, D.C., Foutz, S.R., & Fitzgerald, R.D. (1984). Baroreceptor involvement in classically conditioned heart rate responses of restrained rats.Physiology & Behavior, 33: 31–35.
Hoffman, J.W., & Fitzgerald, R.D. (1978). Classically conditioned heart rate and blood pressure in rats based on either electric shock or ammonia fumes reinforcement.Physiology & Behavior, 21: 735–741.
Iwata, J., & LeDoux, J.E. (1988). Dissociation of associative and nonassociative concomitants of classical fear conditioning in the freely behaving rat.Behavioral Neuroscience, 102: 66–76.
Martin, G.K., & Fitzgerald, R.D. (1980). Heart rate and somatomotor activity in rats during signalled escape and yoked classical conditioning.Physiology & Behavior, 25: 519–526.
Plunkett, R.P. (1979). Effect of hippocampal lesions on heart-rate during classical fear conditioning.Physiology & Behavior, 23: 433–437.
Randall, D.C., Brown, D.R., & Kilgore, J.M. (1993). Sympathetic nerve activity in awake rat: relation to behaviorally conditioned changes in BP.FASEB J., 7: A621.
Randall, D.C., Randall, W.C., Brown, D.R., Yingling, J.D., & Raisch, R.M. (1992). Heart rate control in awake dog after selective SA-nodal parasympathectomy.American Journal Physiology (Heart Circulatory Physiology, 31): H1128-H1135.
Randall, D.C., Skinner, T.L., & Billman, G.E. (1985). A comparison of the autonomic nervous control of the heart during classical aversive vs. appetitive conditioning in dog.Journal Autonomic Nervous System, 13: 125–136.