Alteration in the level of endogenous hypothalamic prostaglandins induced by delta 9-tetrahydrocannabinol in the rat.

1 Whole brain and regional brain levels of prostaglandin E2 (PGE2)-like material have been determined following administration of delta 9-tetrahydrocannabinol (delta 9 -THC) in rats. 2 Intravenous administration of delta 9-THC 2 mg/kg, resulted in marked behavioural changes and hypothermia. The behavioural changes consisted mainly of catatonia (most apparent at 30 min after administration of delta 9-THC), followed by sedation (most evident at 60 min). Hypothermia was marked from 30 min after administration of delta 9-THC. 3 delta 9-THC did not after the whole brain levels of PGE2-like material 30, 60 or 120 min after administration. 4 delta 9-THC did not alter the levels of PGE2-like material in the medulla oblongata/pons, midbrain, cortex and cerebellum, 30 min after administration. However, there was a significant reduction of PGE2-like material in the hypothalamus, 30 min after delta 9-THC. 5 It is suggested that the delta 9-THC-induced decrease in hypothalamic PGE2-like material may contribute to the hypothermia observed following delta 9-THC administration.