Origin and postnatal development of nerves showing 5-hydroxytryptamine-like immunoreactivity supplying major cerebral arteries of the rat.

Nerve plexuses showing 5-hydroxytryptamine (5-HT)-like immunoreactivity (5-HTLI) have been demonstrated in all the major cerebral arteries of the rat using fluorescence immunohistochemistry on whole-mount stretch preparations. Following bilateral superior cervical ganglionectomy, nerves disappeared from all the vessels studied with the exception of the vertebral and basilar arteries where fibres remained. Using image analysis, the density of nerves containing 5-HTLI showed little change between vessels from 3 to 4-week-old and 6 to 7-week-old animals, in contrast to another study which has shown marked reductions in 5-HT-immunoreactive neuronal cell bodies in the superior cervical ganglion over the same period of early development. It was concluded that while the terminals of cerebrovascular nerves retain the capacity to synthesise and/or store 5-HT throughout life, their cell bodies may lose this function soon after birth.