First evidence of melatonin receptors distribution in the suprachiasmatic nucleus of tree shrew brain.
OBJECTIVE
In this study we investigated the distribution of melatonergic receptors in the tree shrew brain. The psychosocial stress in the tree shrew is a validated model of depression with disturbance of circadian rhythms.


METHODS
Given the role of melatonin in the modulation of circadian rhythms, we determined by autoradiography the distribution of binding sites of 2-[125I]-MLT, a ligand for the two melatonergic receptors MT1 and MT2, in the tree shrew brain focusing mostly on the suprachiasmatic nucleus (SCN), the biological clock involved in resynchronization of circadian rhythms. We also analyzed the distribution of 2-[125I]-MLT in other brain areas involved in regulation of mood.


RESULTS
Specific binding of 2-[125I]-MLT was found in the SCN. In addition, several structures in the tree shrew brain were labeled, among them the pars tuberalis, the cerebellum, structures of the hippocampal formation and dopaminergic areas such as the caudate putamen and nucleus accumbens, providing other potential targets of psychosocial stress in the tree shrew, in addition to the SCN.


CONCLUSIONS
The demonstration of melatonergic receptors in these brain areas supports their probable involvement in the behavioural, neuroendocrine and circadian rhythms disturbances observed in the psychosocial stress model of depression in the tree shrew.
Legros
Céline
C
INRA, UMR85 Physiologie de Reproduction et des Comportements, F-37380 Nouzilly, France.
Chalivoix
Stéphanie
S
Gabriel
Cecilia
C
Mocaer
Elisabeth
E
Delagrange
Philippe
P
Fuchs
Eberhard
E
Malpaux
Benoît
B
D000081:Acetamides / Q000494:pharmacology; D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002940:Circadian Rhythm; D005260:Female; D008550:Melatonin / Q000378:metabolism; D008568:Memory; D044094:Receptors, Melatonin / Q000032:analysis* / Q000502:physiology; D013315:Stress, Psychological / Q000503:physiopathology / Q000523:psychology; D013493:Suprachiasmatic Nucleus / Q000737:chemistry*; D014418:Tupaiidae; D009281:Naphthalenes
D000081:Acetamides; D008550:Melatonin; D044094:Receptors, Melatonin; C084711:agomelatine; D009281:Naphthalenes