Acute reversible inactivation of the ventral medial prefrontal cortex induces antidepressant-like effects in rats.
The ventral medial prefrontal cortex (vMPFC) has direct connections to subcortical, diencephalic and brainstem structures that have been closely related to depression. However, studies aimed at investigating the role of the vMPFC in the neurobiology of depression have produced contradictory results. Moreover, the precise involvement of vMPFC anatomic subdivisions, the prelimbic (PL) and the infralimbic (IL) cortices, in regulating depressive-like behavior have been poorly investigated. The forced swimming test (FST) is a widely employed animal model aimed at detecting antidepressant-like effects. Therefore, to further investigate a possible involvement of the vMFPC in depressive-like behavior, rats bilaterally implanted with cannulae aimed at the PL or IL prefrontal cortices were submitted to 15 min of forced swimming (pre-test) followed, 24h later, by a 5-min swimming session (test), where immobility time was registered. Synaptic transmission in these regions was temporarily inhibited using local microinjection of cobalt chloride at different periods of the experimental procedure (before or after the pre-test or before the test). PL inactivation decreased immobility time independently of the time of the injection. In the IL, inactivation induced a significant antidepressant-like effect when performed immediately before the pre-test or before the test, but not after the pre-test. These results suggest that activation of the vMPFC is important for the behavioral changes observed in rats submitted to the FST. They further indicate that, although both the PL and IL cortices are involved in these effects, they may play different roles.
Scopinho
America Augusto
AA
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
Scopinho
Michele
M
Lisboa
Sabrina Francesca
SF
Correa
Fernando Morgan de Aguiar
FM
Guimarães
Francisco Silveira
FS
Joca
Sâmia Regiane Lourenço
SR
D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D003035:Cobalt / Q000008:administration & dosage / Q000494:pharmacology; D003863:Depression / Q000503:physiopathology*; D004195:Disease Models, Animal; D008297:Male; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013550:Swimming / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects*
D000928:Antidepressive Agents; D003035:Cobalt; C018021:cobaltous chloride