Abstract
Emerging evidence points to an involvement of nicotinic acetylcholine receptors (nAChRs) in major depression. Nicotine improves symptoms of depression in humans and shows antidepressant-like effects in rodents. Monoamine release is facilitated by nAChR stimulation, and nicotine-evoked serotonin (5-HT) release has been shown to depend on α7 nAChR activation. The α7 nAChR agonist PNU-282987 shows no antidepressant-like activity when tested alone in the mouse forced swim (mFST) or tail suspension tests (mTST). However, in combination with a sub-active dose of the selective 5-HT reuptake inhibitor citalopram, inducing ~50% 5-HT reuptake inhibition, PNU-282987 has shown marked antidepressant-like effects in the mFST. SSR180711 is a recently described α7 nAChR agonist that has shown antidepressant-like activity in the rat forced swim test. To address the possibility that 5-HT reuptake inhibition contributes to the antidepressant-like profile of SSR180711, we compared the behavioural and biochemical profiles of PNU-282987 and SSR180711. In the mFST and mTST, SSR180711 (3-30 mg/kg, s.c.) showed dose-dependent antidepressant-like activity, while PNU-282987 (3-30 mg/kg, s.c.) showed no significant effect. The ED(50) to displace [³H]α-bungarotoxin binding was 1.7 and 5.5 mg/kg for SSR180711 and PNU-282987, respectively, suggesting that both compounds produce near-maximal α7 nAChR occupancy at the highest dose. While PNU-282987 did not affect ex vivo [³H]5-HT uptake, SSR180711 inhibited [³H]5-HT uptake with an ED₅₀ of 30 mg/kg. This degree of inhibition is similar to that observed with a citalopram dose of ~2.4 mg/kg, a dose that is normally not active in the mFST or mTST. This suggests that the antidepressant-like activity of SSR180711 may involve partial 5-HT reuptake inhibition. SSR180711 therefore represents a compound displaying the synergistic effect of α7 nAChR agonism combined with partial 5-HT reuptake inhibition previously described. The addition of α7 nAChR agonism to classical monoamine-based mechanisms may represent a novel option for the improved treatment of major depression.
Originalsprog | Engelsk |
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Tidsskrift | Pharmacology, Biochemistry and Behavior |
Vol/bind | 100 |
Udgave nummer | 3 |
Sider (fra-til) | 624-9 |
Antal sider | 6 |
ISSN | 0091-3057 |
DOI | |
Status | Udgivet - jan. 2012 |
Emneord
- Animals
- Antidepressive Agents
- Behavior, Animal
- Benzamides
- Bicyclo Compounds
- Bicyclo Compounds, Heterocyclic
- Cerebral Cortex
- Citalopram
- Depression
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drug Synergism
- Drug Therapy, Combination
- Female
- Mice
- Mice, Inbred Strains
- Molecular Targeted Therapy
- Nicotinic Agonists
- Receptors, Nicotinic
- Serotonin
- Serotonin Plasma Membrane Transport Proteins
- Serotonin Uptake Inhibitors
- Tissue Distribution
- alpha7 Nicotinic Acetylcholine Receptor