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TOLERANCE TO THE EFFECTS OF Δ 1 ‐TETRAHYDROCANNABINOL ON THE PRESSOR RESPONSES TO NORADRENALINE IN RATS
Author(s) -
Li D. M. F.
Publication year - 1981
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1981.tb00140.x
Subject(s) - delta 9 tetrahydrocannabinol , chronotropic , pressor response , medicine , chemistry , delta , δ9 tetrahydrocannabinol , endocrinology , norepinephrine , blood pressure , anesthesia , pharmacology , heart rate , cannabinoid , receptor , dopamine , engineering , aerospace engineering
SUMMARY l. The depressor response, but not the cardiac slowing response, to the acute intravenous administration of Δ 1 ‐THC (1 mg/kg) was significantly reduced in urethane anaesthetized rats, which had been treated with daily injections of Δ 1 ‐THC (2 mg/kg, i.p.) for 10 days ( P <0.01). 2. No significant differences in either the depressor or the negative chronotropic effects of an acute intravenous injection of Δ 1 ‐THC (1 mg/kg) were observed in anaesthetized rats which had been treated with PVP (8 mg/kg per day, i.p.) for 10 days. 3. The depressor and cardiac slowing responses to an acute intravenous dose of Δ 1 ‐THC (1 mg/kg) were not significantly different between Δ 1 ‐THC‐ and PVP‐treated animals which had been pithed. 4. The potentiating effects of Δ 1 ‐THC on the pressor responses to intravenously administered noradrenaline were significantly reduced ( P <0.001) in urethane anaesthetized rats which had been treated with Δ 1 ‐THC, but not in anaesthetized PVP‐treated animals. 5. Tolerance to the potentiating effect of Δ 1 ‐THC on the responses to noradrenaline has also been demonstrated in anaesthetized Δ 1 ‐THC‐treated rats, but not in pithed Δ 1 ‐THC treated ones. 6. It is concluded that the development of tolerance to the depressor action of Δ 1 ‐THC, and its potentiating effect on the noradrenaline pressor responses requires the presence of an intact central nervous system.