Serotonin Receptors in Ischemic Brain Edema

The involvement of serotonin (5-hydroxytryptamine, 5-HT) in the development of cerebral edema of both vasogenic and cytotoxic types has been the subject of many investigations since the late 1950s [1, 2, 9–13, 15; Mrsulja et al., this volume]. In particular, the studies of Welch first drew attention to the possible relationship of 5-HT to the formation of edema in ischemia [15]. Similar conclusions were also derived from our studies of cerebral edema in ischemic gerbils [9–12; Mrsulja et al., this volume]. However, we not only observed a close correlation between the accumulation of water content and the alteration of 5-HT metabolism but also an association of water increment with changes in the activity of Na+-K+-ATPase, Na+:K+ ratio, and levels of cAMP in the brain [11, 12; Mrsulja et al., this volume]. These findings suggested the possibility of interrelated events occurring in ischemia which might affect the cellular membranes and lead to edema. Since the disturbance of the cerebral 5-HT pathway might be one of the main processes involved in the formation of edema, we investigated the kinetic properties of cellular 5-HT (S2 postsynaptic) receptors in the gerbil model.