[Abstract Title]. - Society for Neuroscience

has determined the neuroanatomical site mediating the antidepressant effect of CB1 receptor
antagonism. Given the importance of corticolimbic structures, such as the prefrontal cortex and
amygdala, in the regulation of coping response to stress, the current study sought to determine if
CB1 receptor signaling in subregions of the frontal cortex and the amygdala differentially
regulate stress-coping behavior. To this extent we assessed the effects of discrete infusions of a
CB1 receptor agonist (HU-210) or antagonist (AM251) directly into the vmPFC or the anterior
cingulate cortex (ACC) within the frontal cortex, as well as within the basolateral, central and
medial nuclei of the amygdala, on behavioral responses in the Porsolt forced swim test.
Administration of the CB1 receptor agonist HU210 into the vmPFC decreased immobility and
increased swimming in the forced swim test, indicating that this treatment evoked an
antidepressant response, while the CB1 receptor antagonist AM251 had no effect. Alternately,
infusions of AM251 into the ACC resulted in a dose-dependent antidepressant response as
revealed by a reduction in immobility, while infusion of HU-210 had no significant effects on
behavioral responses in the forced swim test. Within the amygdala, we have determined that
administration of AM251 into the basolateral amygdala has no effect on stress coping behavior
in the forced swim test. Ongoing studies are examining the effects of AM251 and HU-210 into
the medial and central nuclei of the amygdala in the forced swim test. Collectively, these data
argue that CB1 receptor signaling in distinct fronotocortical subregions has differential effects on
emotional behavior, and that the ACC may be an integral neuroanatomical site mediating the
reported antidepressant effects seen following systemic administration of a CB1 receptor
antagonist.
Disclosures: R.J. McLaughlin , None; M.N. Hill, None; A.C. Morrish, None; B.B. Gorzalka,
None.
Poster
255. Mood Disorders: Animal Models and Treatment Effects II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 255.2/Y17
Topic: C.15.h. Affective disorders: Animal models
Support: FAPESP
CNPQ
FAEPA
Title: Activation of CB1 cannabinoid receptors in Medial Prefrontal Cortex modulate the
expression of contextual fear conditioning in rats