When injected into the fimbria-fornix/cingular bundle, not in the raphe, 5,7-dihydroxytryptamine prevents amphetamine-induced hyperlocomotion.
The locomotor effects of acute amphetamine treatment (1 mg/kg, i.p.) were assessed in Long-Evans rats after 5,7-dihydroxytryptamine (5, 7-DHT) injections into the fimbria-fornix/cingular bundle (FiFx/CB; 4 microg/side), or the dorsal and median raphe (Raphe; 10 microg). In control rats, amphetamine induced a significant increase of home-cage activity for about 2 h. This effect was similar in Raphe rats, but was absent in FiFx/CB rats. The raphe lesions reduced serotonin concentrations by 50% in the dorsal hippocampus, 75% in the ventral hippocampus and 58% in the fronto-parietal cortex. After FiFx/CB lesions, the reduction amounted 50, 61 and only 25%, in each of these regions, respectively. In the fronto-partietal cortex, dopamine concentration was significantly decreased in Raphe (-27%) and FiFx/CB rats (-65%). The results suggest that a serotonergic denervation of the hippocampus by injections of 5,7-DHT into the FiFx/CB pathways hampers the stimulating effects of amphetamine on locomotor activity. This effect might be related to the reduced dopaminergic tone in the fronto-parietal cortex.
Lehmann
O
O
Laboratoire de Neurosciences Comportementales et Cognitives, UMR 7521 Université Louis Pasteur/CNRS 12, rue Goethe, 67000, Strasbourg, France.
Jeltsch
H
H
Bertrand
F
F
Lazarus
C
C
Will
B
B
Cassel
J
J
D015116:5,7-Dihydroxytryptamine / Q000008:administration & dosage / Q000494:pharmacology*; D000661:Amphetamine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D000697:Central Nervous System Stimulants / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology; D020712:Fornix, Brain / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D011903:Raphe Nuclei / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D018490:Serotonin Agents / Q000008:administration & dosage / Q000494:pharmacology*
D000697:Central Nervous System Stimulants; D018490:Serotonin Agents; D015116:5,7-Dihydroxytryptamine; D000661:Amphetamine; D004298:Dopamine