Time dependent effect of GM, ganglioside administration upon [(3)H]5-hydroxytryptamine uptake in partially denervated rat hippocampus.

The effect of GM(1) administration upon the time course of the postlesion changes of [(3)H]5hydroxytryptamine uptake in the partially denervated rat hippocampus has been studied 6, 21, 42 and 90 days after surgery. At 6 and 21 days after operation the postlesion decrease of [(3)H]5-hydroxytryptamine uptake was counteracted by GM(1) administration. This effect was limited to the most denervated dorsal hippocampal part, where the lesion-evoked decrease of [(3)H]5-hydroxytryptamine uptake was the strongest. After longer postoperative periods (42 and 90 days) the potentiating effect of GM(1) disappeared. On the other hand, prolonged GM(1) administration (21-90 days) to unoperated animals caused a small but significant reduction of [(3)H]5-hydroxytryptamine uptake, equal in all three hippocampal parts. The early postlesion facilitation of [(3)H]5-hydroxytryptamine uptake due to GM(1) treatment was most probably related to protection against secondary degeneration of serotonergic fibers not directly affected by the lesion.