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Systemic injection of marihuana distillate extract, of whichΔ 9-tetrahydrocannbinol (Δ 9-THC) is the major single constituent, inhibits the release of radioiodine from the thyroid gland of the rat. Administration of thyroid stimulating hormone (TSH) resulted in increased output of iodine in animals pretreated withΔ 9-THC. These data suggest that reduced TSH secretion is the primary cause of the thyroid inhibition induced by THC. Bilateral electrolytic lesions in the region of the medial mammillary nuclei of the hypothalamus prevented the decrease in pituitary-thyroid activity induced by THC, whereas lesions in the rostral hypothalamus did not effect the response. These results indicate that THC inhibits pituitary-thyroid function due to an action on neurons in the caudal hypothalamus. The possibility is discussed that these effects are due to stimulation of specific inhibitory centers rather than depression of neurons responsible for tonic release of TSH. Marihuana appears to have a similar action to morphine in modifying pituitary-thyroid function.

A reliable chemical means of assaying small quantities of marihuana or tetrahydrocannabinol (THC) isomers in body fluids and cell preparations has long been sought. A possible immunological approach was suggested by work with oestrogen haptens. It was established earlier that diazobenzoic acid under appropriate conditions enters the A ring by virtue of the phenolic function of C-3, yielding oestrogen azobenzoic acid derivatives1, 2. These compounds are coupled readily through the benzoyl carboxyl to proteins and solid matrices containing accessible NH2 groups, retaining the important antigenic specificities contributed by the reactive −OH and = O groups as well as those associated with the ringed backbone1, 3. Other biologically important molecules which lend themselves to similar manipulation are the principal psychotomimetics. In our search for useful haptens and active antibodies to be used in a reliable model assay system, we have chosen to report the investigation of THC. Similar results have been achieved with the phenanthrene alkaloids (S. J. G., unpublished) preserving all the determinant functional groups * unlike the reagent for morphine assay recently reported4.