Cerebrovascular response to infused 5-hydroxytryptamine in the baboon. Part 2. 5 Hydroxytryptamine infusion in estrogen and progesterone treated animals.

The effect of intracarotid infusion of 5-hydroxytryptamine (5-HT) on cerebral blood flow was studied in five female baboons 7 days after intramuscular injection of slow release estrogen and progesterone. The control values for total cerebral blood flow, grey matter flow, and white matter flow were 38.9, 57.5, and 11.0 ml/min/100 gm of tissue respectively. There was a statistically significant decrease in total, grey and white matter blood flow during infusion of 5-HT at dosages ranging from 0.5 to 10.0 microng/kg/min. The study indicates that in female baboons pretreated with estrogen and progesterone, intracarotid infusion of 5-HT produces a dose dependent decrease in cerebral blood flow, which did not occur in control animals.