Table 1.
A Comparison Between the Psychological and Neurobiological Symptoms of Melancholic Depression and the Phenotype of MT1 Receptors Knockout Mice.
| Symptoms of melancholic depression (Parker et al., 2010) | MT1 receptors knockout mice |
|---|---|
| Anhedonia | Anhedonia (↓ sucrose preference) |
| Depression | Depression-like behavior (↑ immobility in FST and TST; ↑ latency to eat in NSFT) |
| Weight loss | ↓ Weight |
| Psychomotor disturbances (agitation or retardation) | Hyperlocomotion (↑ locomotion in OFT), disinhibition (↑ open arm time and entries in EPMT, ↑ head dips in EPMT) |
| Circadian variation of mood | behavioral light/dark differences |
| Hypercortisolemia | ↑ corticosterone serum levels during the dark phase, no light/dark differences in corticosterone levels |
| Disturbance in sleep architecture especially at the level of REMS | ↓ REMS duration, ↓ NREMS EEG delta power and REMS EEG theta power (36) |
| Monoamine activity alterations | ↓ DRN 5-HT and LC NE neuronal bursts activity; altered light/dark firing pattern of DRN 5-HT and LC NE neurons |
| Genetic causes | Genetic inactivation of MT1 receptors |
↑ = increase; ↓ = decrease. DRN, dorsal raphe nucleus; EEG, electroencephalographic; EPMT, elevated plus maze test; FST, forced swim test; LC, locus coeruleus; NE, norepinephrine; NREMS, non-REMS; NSFT, novelty-suppressed feeding test; OFT, open field test; REMS, rapid eye movement sleep; TST, tail suspension test.