Galanin/5-HT interactions in the rat central nervous system. Relevance for depression

During recent years we have obtained evidence for the existence of galanin (GAL)/5-hydroxytryptamine (5-HT) interactions at the pre-and postsynaptic level in the rat central nervous system (CNS). The main basis of these interactions appear to be bidirectional intramembrane interactions between GAL and 5-HT1A receptors (Fuxe et al., 1988a, 1990) which represents a way to increase plasticity of 5-HT neurotransmission, since the 5-HT1A receptor appears to be selectively modulated by GAL (Fuxe et al, 1988a). Recent work by Hedlund et al. (1990) indicates that in fact the 5-HT1A receptor subtype is regulated by an intramembrane feedback loop involving the high affinity GAL receptor.