Antidepressant- and anxiolytic effects of the novel melatonin agonist Neu-P11 in rodent models.
OBJECTIVE
To investigate the potential antidepressant and anxiolytic effects of Neu-P11, a novel melatonin agonist, in two models of depression in rats and a model of anxiety in mice.


METHODS
In the learned helplessness test (LH), Neu-P11 or melatonin (25-100 mg/kg, ip) was administered to rats 2 h before the beginning of the dark phase once a day for 5 days and the number of escape failures and intertrial crossings during the test phase were recorded. In the forced swimming test (FST), rats received a single or repeated administration of Neu-P11 (25-100 mg/kg, ip). The total period of immobility during the test phase was assessed. In the elevated plus-maze test (EPM), mice were treated with Neu-P11 (25-100 mg/kg, ip) or melatonin in the morning or in the evening and tested 2 h later. The percentage of time spent in the open arms and the open arms entries were assessed.


RESULTS
In the LH test, Neu-P11 but not melatonin significantly decreased the escape deficit and had no effect on the intertrial crossings. In the FST, a single or repeated administration of Neu-P11, either in the morning or in the evening, significantly decreased the duration of immobility. In the EPM test, Neu-P11 significantly increased the percentage of time spent in the open arms and the open arms entries irrespective to the time of administration. Melatonin was effective only when administered in the afternoon.


CONCLUSIONS
The results demonstrate that Neu-P11 exerts antidepressant and anxiolytic activities in rodent models.
Tian
Shao-wen
SW
Department of Physiology, University of South China, Hengyang, China. tsw.neuro@126.com <tsw.neuro@126.com>
Laudon
Moshe
M
Han
Li
L
Gao
Jun
J
Huang
Fu-lian
FL
Yang
Yu-feng
YF
Deng
Hai-feng
HF
D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage / Q000494:pharmacology; D000928:Antidepressive Agents / Q000008:administration & dosage / Q000494:pharmacology; D001007:Anxiety / Q000188:drug therapy*; D002940:Circadian Rhythm; D003863:Depression / Q000188:drug therapy*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D008297:Male; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D044094:Receptors, Melatonin / Q000819:agonists*; D013550:Swimming; D013997:Time Factors
D014151:Anti-Anxiety Agents; D000928:Antidepressive Agents; D044094:Receptors, Melatonin