Cerebral perivascular serotonergic fibres have a peripheral origin in the gerbil

The origin of serotonergic nerves supplying the large cerebral vessels of the gerbil has been investigated after bilateral superior cervical ganglionectomy. Immunohistochemical techniques were applied to whole-mount stretch preparations of the cerebral vessels. Removal of both ganglia resulted in the complete loss of immunoreactive fibres in the vessels supplied by the internal carotid artery and in a marked reduction of fibres innervating vessels of the vertebro-basilar system, indicating that most of the cerebrovascular serotonergic nerves have a peripheral sympathetic origin in the gerbil. The contrast with the central origin of serotonergic perivascular nerves claimed in the rat is discussed.