ABSTRACT
Objective To explore the expression of acid-sensing ion channel 1a ( ASIC1a) in cen-tral nervous system of mice with panic like behavior. Methods 20 male C57BL/6 mice were randomly di-vided into two groups according to their weight( 10 mice in each group):the group experienced rat exposure test of panic-like behavior model ( RET group ) and the control group ( Ctr group ) . A panic-like behavior model was established by rat exposure stimuli. Ten minutes defensive and avoidance behaviors of mice were recorded with a horizontal video camera. The anxiety level of mice was evaluated by elevated plus maze ( EPM) test.Western blot was used to detect the ASIC 1a expression in different brain areas of prefrontal cor-tex,hippocampus and periaqueductal gray (PAG). Results Compared with Ctr group,mice in RET group spent significantly more time in freezing ((5.83±1.92)s) than that of Ctr group ((1.00±0.45)s) (P<0.01),had significantly higher frequency of risk assessment behavior (5.33±0.49) than that of Ctr group (0.60±0.40) (P<0.01),spent significantly less time to contact the wire mesh ((17.83±4.38)s) than that of Ctr group((50.00±6.90)s) (P<0.01),and significantly more time of staying in the protected area((431.00±33.13)s) than that of Ctr group((264.40±40.43)s) (P<0.01).At the same time,RET group showed sig-nificantly lower time percent ((8.28±1.12)％) than Ctr group ((16.81±2.13)％) in opened arm (P<0.05) and significantly higher time percent ((80.08±4.26)％) than Ctr group ((60.91±5.27)％) in the closed arm (P<0.05).Western blot suggested that the expression level of ASIC 1a in the prefrontal cortex (1.32± 0.05) and hippocampus (2.56±0.30) significantly increased than that of Ctr group((0.98±0.07),(1.56± 0.16)( P<0.05),while significantly decreased in the PAG (0.83± 0.02) than that of Ctr group(1.26±0.05) ( P<0.05) . Conclusion Rat exposure stimuli can induce panic-like behavior among mice,which increases the expression of ASIC 1a in the prefrontal cortex and hippocampus,but decreases the level of ASIC 1a in the PAG.
ABSTRACT
The hypothalamus is a forebrain structure critically involved in the organization of defensive responses to aversive stimuli. Gamma-aminobutyric acid (GABA)ergic dysfunction in dorsomedial and posterior hypothalamic nuclei is implicated in the origin of panic-like defensive behavior, as well as in pain modulation. The present study was conducted to test the difference between these two hypothalamic nuclei regarding defensive and antinociceptive mechanisms. Thus, the GABA A antagonist bicuculline (40 ng/0.2 µL) or saline (0.9% NaCl) was microinjected into the dorsomedial or posterior hypothalamus in independent groups. Innate fear-induced responses characterized by defensive attention, defensive immobility and elaborate escape behavior were evoked by hypothalamic blockade of GABA A receptors. Fear-induced defensive behavior organized by the posterior hypothalamus was more intense than that organized by dorsomedial hypothalamic nuclei. Escape behavior elicited by GABA A receptor blockade in both the dorsomedial and posterior hypothalamus was followed by an increase in nociceptive threshold. Interestingly, there was no difference in the intensity or in the duration of fear-induced antinociception shown by each hypothalamic division presently investigated. The present study showed that GABAergic dysfunction in nuclei of both the dorsomedial and posterior hypothalamus elicit panic attack-like defensive responses followed by fear-induced antinociception, although the innate fear-induced behavior originates differently in the posterior hypothalamus in comparison to the activity of medial hypothalamic subdivisions.