en Nervous system (others) Others Experimental research article Experimental research article Traditionally, Peganum harmala seeds (P.h) have been extensively used in the Asia region. We have previously reported the increase of fear behavior by systemic administration of P.h extract. Here, we evaluated the effect of central administration of the extract on the fear behavior. Method: Methanolic extract of the plant's seeds (37% humidity) was prepared for the investigation. Elevated plusmaze apparatus was used for evaluating the fear behavior. Adult male rats were categorized in 7 main groups (n=6). 1) Sham control (saline 1 ul/rat, i.c.v) 2) Harmaline treated group (50 ug/rat, i.c.v). 3) Extract treated groups (10, 20, 25, 50, 100 ug/rat i.c.v respectively). Results: All the doses of the P.h Methanolic extract as like as harmaline caused fear behavior (p<0.05). There was no significant difference between the effects of harmaline and the doses of the plant extract. Discusion: Overall, it is possible that the main alkaloid of the P.h (harmaline) is responsible for the increasing of fear behavior. The effect seems to be done trough the central nervous system neurochemical mechanisms. Peganum harmala , i.c.v, plus-maze, ethanolic extract, rat. 300 305 http://ppj.phypha.ir/browse.php?a_code=A-10-97-1&slc_lang=en&sid=1 Vaezi Gholamhassan 320031947532846003352 320031947532846003352 No Masoud Fereidoni 320031947532846003353 320031947532846003353 No Leila Etemadi ll_etemadi@yahoo.com 320031947532846003354 320031947532846003354 Yes Maryam Sabzali 320031947532846003355 320031947532846003355 No