Repeated lysergic acid diethylamide in an animal model of depression: Normalisation of learning behaviour and hippocampal serotonin 5-HT2 signalling.
A re-balance of postsynaptic serotonin (5-HT) receptor signalling, with an increase in 5-HT1A and a decrease in 5-HT2A signalling, is a final common pathway multiple antidepressants share. Given that the 5-HT1A/2A agonist lysergic acid diethylamide (LSD), when repeatedly applied, selectively downregulates 5-HT2A, but not 5-HT1A receptors, one might expect LSD to similarly re-balance the postsynaptic 5-HT signalling. Challenging this idea, we use an animal model of depression specifically responding to repeated antidepressant treatment (olfactory bulbectomy), and test the antidepressant-like properties of repeated LSD treatment (0.13 mg/kg/d, 11 d). In line with former findings, we observe that bulbectomised rats show marked deficits in active avoidance learning. These deficits, similarly as we earlier noted with imipramine, are largely reversed by repeated LSD administration. Additionally, bulbectomised rats exhibit distinct anomalies of monoamine receptor signalling in hippocampus and/or frontal cortex; from these, only the hippocampal decrease in 5-HT2 related [(35)S]-GTP-gamma-S binding is normalised by LSD. Importantly, the sham-operated rats do not profit from LSD, and exhibit reduced hippocampal 5-HT2 signalling. As behavioural deficits after bulbectomy respond to agents classified as antidepressants only, we conclude that the effect of LSD in this model can be considered antidepressant-like, and discuss it in terms of a re-balance of hippocampal 5-HT2/5-HT1A signalling.
Institute of Pharmacology and Toxicology, Otto-von-Guericke University, Magdeburg, Germany tobias.buchborn@med.ovgu.de.
Tobias
T
Buchborn
Institute of Pharmacology and Toxicology, Otto-von-Guericke University, Magdeburg, Germany.
Helmut
H
Schröder
Institute of Pharmacology and Toxicology, Otto-von-Guericke University, Magdeburg, Germany.
Volker
V
Höllt
Institute of Pharmacology and Toxicology, Otto-von-Guericke University, Magdeburg, Germany.
Gisela
G
Grecksch
D000818:Animals; D000928:Antidepressive Agents / Q000008:administration & dosage*; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects*; D003863:Depression / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology / Q000523:psychology; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008238:Lysergic Acid Diethylamide / Q000008:administration & dosage*; D008297:Male; D009830:Olfactory Bulb / Q000601:surgery; D017208:Rats, Wistar; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects*; D013997:Time Factors
D000928:Antidepressive Agents; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D008238:Lysergic Acid Diethylamide
Serotonergic hallucinogen; animal model; antidepressant; avoidance learning; hippocampus; lysergic acid diethylamide; olfactory bulbectomy; serotonin 5-HT2A receptor