Increased density of galanin binding sites in the dorsal raphe in a genetic rat model of depression

The Flinders Sensitive Line rats showed an increased immobility response by 104% (P < 0.01) in the forced swim test with respect to the Flinders Resistant Line rats (control). The Flinders Sensitive Line rats also had an increase of [I-125]galanin (porcine) binding in the dorsal raphe (55 +/- 3.3 fmol/mg protein) with respect to the Flinders Resistant Line rats (38 +/- 3.6 fmol/mg protein) (42%, P < 0.05) without changes in galanin receptor affinity and with a significant reduction (32.3%, P < 0.05) of galanin-like immunoreactivity in the dorsal raphe. The results indicate that enhancement of galanin receptor function in the dorsal raphe rich in 5-HT neurons could be a mechanism involved in the production of depressive-like activity in this animal model of depression. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.