Effect of Allopregnanolone injected into the Medial Pre-Frontal Cortex in the Plus-Maze Test in rats.

CASTELLER, G.; LACONI, M.; FRAILE, M.; MELONARI, P.; OLGUIN, M.; LLANO, L.; TALEY, S.; TARRAZÓ, M.F.; LANDA, A.; CABRERA, R.J.; GARGIULO, P.A.

Gottingen. Alemania.

Congreso; 30th Gottingen Neurobiology Conference and the 6th Meeting of the German Neuroscience Society. Communication 226B.; 2005

Sociedd Alemana de Neurociencias.-

The medial Pre-Frontal Cortex (mPFC) projects to the Nucleus Accumbens Septi (Acc), and these projections has been implicated in emotional driving. In previous reports, we have communicated that glutamatergic transmission within Acc modulates anxiety. Additionally, we have previously reported the action of intracerebroventricular administration of Allopregnanolone (ALL) induces an anxiolytic like effect in rats in the plus maze test. The aim of the present work is to study the behavioral action of ALL in male rats  bilaterally cannulated into the mPFC in the plus maze test. Rats were divided in three groups (n=8-13). They received either 1 ìl injections of Krebs solution or ALL (0.06 or 0.06 mM). Time spent into the open arm and the time spent in the distal extreme of the open arm were significantly increased by both doses (p<0.001) when compared with controls. Open arm entries were increased by the lower (p<0.001) and the higher (p<0.05) doses. Closed arm entries were increased only by the lower dose (p<0.05). No differences were seen in the quotient time spent in the open arm / number of entries to the open arm. All these results show that ALL has an anxiolytic-like effect, and a disinhibitory action when injected into the mPFC. We conclude that present results show a new modulatory action of ALL in mPFC mediating anxiety levels in male rats, and also an important evidence about the role of forebrain structures in the mediation of anxiety.