DUAL ACTIVATION OF CARDIAC SYMPATHETIC AND PARASYMPATHETIC COMPONENTS DURING CONDITIONED FEAR TO CONTEXT IN THE RAT
- 20 December 2006
- journal article
- Published by Wiley in Clinical and Experimental Pharmacology and Physiology
- Vol. 33 (12), 1251-1254
- https://doi.org/10.1111/j.1440-1681.2006.04519.x
Abstract
1. The present study investigates the contribution of the sympathetic and vagal parasympathetic systems to the tachycardic response of long-lasting (40 min) conditioned fear responses to context. 2. The conditioned fear response evoked by re-exposure to a footshock chamber was tested 10 min after intravenous injection of the beta-adrenoceptor antagonist propranolol (2 mg/kg) or the muscarinic antagonist atropine methyl nitrate (2 mg/kg) in rats implanted with radiotelemetric probes. 3. Compared with saline controls, the drugs did not change the behavioural component of the response (freezing, 22 kHz ultrasonic vocalizations) or its pressor component (+28 mmHg). 4. Propranolol abolished the tachycardic response of fear, whereas atropine more than doubled it (from +75 to +175 b.p.m. above resting baseline). 5. The results demonstrate that both sympathetic and vagal parasympathetic outflows to the heart are strongly activated during conditioned fear. The vagal activation may act to hold back cardiac acceleration while the animal waits for the aversive stimulus to come.Keywords
This publication has 11 references indexed in Scilit:
- Baroreceptor function during exercise: resetting the recordExperimental Physiology, 2005
- Expression of cardiovascular and behavioural components of conditioned fear to context in T4 spinally transected ratsAutonomic Neuroscience, 2005
- Changes in cutaneous and body temperature during and after conditioned fear to context in the ratEuropean Journal of Neuroscience, 2005
- Role of ventrolateral periaqueductal gray neurons in the behavioral and cardiovascular responses to contextual conditioned fear and poststress recoveryNeuroscience, 2003
- Cardiovascular and behavioural components of conditioned fear to context after ganglionic and α-adrenergic blockadeAutonomic Neuroscience, 2002
- Conditioned fear to environmental context: cardiovascular and behavioral components in the ratBrain Research, 2000
- The neuroanatomical and neurochemical basis of conditioned fearNeuroscience & Biobehavioral Reviews, 1999
- Discriminative fear conditioning to context expressed by multiple measures of fear in the ratBehavioural Brain Research, 1999
- Dissociation of associative and nonassociative concomitants of classical fear conditioning in the freely behaving rat.Behavioral Neuroscience, 1988
- Crouching as an index of fear.Journal of Comparative and Physiological Psychology, 1969