Sex differences in alpha-adrenergic receptors in the rat brain.

[3H]Dihydroergocryptine ([3H]DHE) binding to several brain regions was studied in male and female rats, the latter in two different endocrinological states (estrous and diestrous-1). males showed higher [3H]DHE binding than females in hypothalamus, hippocampus and olfactory bulb, while females showed higher levels than males in spinal cord and visual cortex. In addition, intra-sex (that is, estrous versus diestrous-1) differences were detected in the cervico-thoracic spinal cord and cerebellum. Diestrous females presented higher values in both regions.