Cannabinoids

Effects of Cannabinoids on Hypothalamic and Reproductive Function 557

Fig. 1.Schematic drawing of the sagittal section of rat brain 0.4 mm lateral to the midline, according to the
atlasofPaxinos-Watson(1997).Theboxshowsapartoftheforebrain.Theparallellinesindicatefrontalsections
seen in Fig. 2. Thenumbersindicate the distance from the interaural line according to the Paxinos-Watson
atlas. Only the main structures are labelled (for orientation)

temperature. Indeed, the hypothalamus is a brain area that is generally considered
to be particularly important in maintaining homeostasis.

3

Cannabinoids in the Hypothalamus and Pituitary

The presence of endocannabinoids has been shown in the hypothalamus (Herken-
ham 1995) and in the anterior pituitary (Gonzales 1999). The central cannabinoid
receptor (CB 1 receptor) is also present is these structures. The hypothalamus con-
tains fewer cannabinoid binding sites than other areas of the CNS. Nevertheless
the effects caused by the activation of CB 1 receptors in the hypothalamus are im-
portant, maybe because the receptors are more or less concentrated within specific
hypothalamic nuclei-areas (Fig. 2). CB 1 receptorsseemtobelocatedonintrinsic
hypothalamic neurons rather than on neurons with cell bodies located outside the
hypothalamus, since hypothalamic deafferentation is not followed by any reduc-
tion in the number of cannabinoid receptor binding sites within this brain area
(Romero 1998).
Unlike the hypothalamus, the anterior pituitary, which is regulated by hypotha-
lamic releasing and inhibiting factors, contains a large number of CB 1 recep-