Abstract
Spontaneously hypertensive (SH) rats were trained to discriminate the effects of saline injection from the interoceptive stimuli associated with the blood-pressure-reducing effect of clonidine (0.02 mg/kg, IP) in a drug discrimination procedure. Anise/ethanol and ethanol odors were then systematically paired with clonidine and saline treatment, respectively, outside the drug discrimination setting. As the number of pairings increased, the anise/ethanol (but not the ethanol) stimulus, when given alone, came to both reduce blood pressure and to mimic clonidine's interoceptive stimulus to virtually the same extent as clonidine itself. Both responses induced by the conditioned stimulus (CS+; anise/ethanol odor) were antagonized by the noradrenergic alpha-2 receptor antagonist yohimbine at a dose that did not by itself influence blood pressure. These data support the hypothesis that activation of endogenous factors can be elicited by a CS, and that these factors may furthermore act agonistically at central alpha-2 receptors to reduce blood pressure in hypertensive animals.
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References
Barr GA, Sharpless NS, Cooper S, Schiff SR, Paredes W, Bridger WH (1983) Classical conditioning, decay and extinction and cocaine-induced hyperactivity and stereotypy. Life Sci 33:1341–1351
Bennett DA, Lal H (1982) Discriminative stimuli produced by clonidine: an investigation of the possible relationship to adrenoreceptor stimulation and hypotension. J Pharmacol Exp Ther 223:642–648
Drawbaugh R, Lal H (1974) Reversal by narcotic antagonist of a narcotic action elicited by a conditional stimulus. Nature 247:65–67
Drawbaugh R, Lal H (1976) Effect of pharmacological interference with various neuropathways on blockade of morphine-with-drawal hypothermia by morphine and by conditional stimulus. Neuropharmacology 15:375–378
Eikelboom R, Stewart J (1981) Conditioned temperature effects using amphetamine as the unconditioned stimulus. Psychopharmacology 75:96–97
Lal H, Yaden S (1985) Discriminative stimuli produced by clonidine in spontaneously hypertensive rats: generalization to antihypertensive drugs with different mechanisms of action. J Pharmacol Exp Ther 232:33–39
Lal H, Miksic S, Smith N (1976) Naloxone antagonism of conditioned hyperthermia: An evidence for release of endogenous opioid. Life Sci 18:971–976
Perez-Cruet J (1976) Conditioning of striatal dopamine metabolism with methadone, morphine or bulbocapnine as an unconditioned stimulus. Pav J Biol Res 11:237–250
Robson RD, Antonaccio MJ, Saelens JK, Liebman J (1978) Antagonism by mianserin and classical alpha adrenoreceptor blocking drugs of some cardiovascular and behavioral effects of clonidine. Eur J Pharmacol 47:431–442
Roffman M, Lal H (1974) Stimulus control of hexobarbital narcosis and metabolism in mice. J Pharmacol Exp Ther 191:358–369
Roffman M, Reddy C, Lal H (1973) Control of morphine withdrawal hypothermia by conditional stimuli. Psychopharmacology 29:197–201
Yaden S, Palmer RT, Elko EE, Lal H (1985) Comparative activity of antihypertensive drugs as determined by the indirect measurement of blood pressure. Drug Dev Res 5:129–136
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Spencer, D.G., Yaden, S. & Lal, H. Behavioral and physiological detection of classically-conditioned blood pressure reduction. Psychopharmacology 95, 25–28 (1988). https://doi.org/10.1007/BF00212760
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DOI: https://doi.org/10.1007/BF00212760