Brain research bulletin
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Brain research bulletin · Dec 2009
The effects of acute stress and acute corticosterone administration on the immobility response in rats.
The immobility response is an innate antipredatory behavior in a broad variety of species. The immobility response varies in its postural components but in general is characterized by an absence of movement and a relative unresponsiveness to stimuli. Experimentally in rats, clamping the neck followed by body inversion and manual restrain elicits a response called "immobility by clamping the neck". ⋯ We observed that either previous acute stress caused by forced exposure to elevated open platform or application of a heat-pain stimulus to the rat's tail during the immobility increased the duration of the immobility response caused by clamping the neck. Also, the corticosterone produced a rapid increase (15 min after injection) in the duration of this immobility response. Our results show that the acute stress, in rats, is a facilitator of the immobility response and suggest a possible nongenomic rapid action of corticosterone over brain structures that control this behavior.
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Brain research bulletin · Dec 2009
Effect of puerarin on P2X3 receptor involved in hyperalgesia after burn injury in the rat.
The study investigated the effects of puerarin on P2X(3) receptor involved in hyperalgesia after burn injury in the rat. Superficial second degree burn injury models were adopted. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured and the P2X(3) receptor expressions in dorsal root ganglion (DRG) from burn injury models rats were detected by immunohistochemistry, in situ hybridization, RT-PCR and western blot. ⋯ At day 3 post-burn, the expressions of P2X(3) protein and mRNA in DRG neurons in untreated superficial second degree back burn group were increased significantly compared with sham back burn group, puerarin-treated back unburned control group, blank back control group, while in puerarin-treated superficial second degree back burn group, the P2X(3) protein and mRNA expressions were decreased markedly. There is no significant difference in sham back burn group, puerarin-treated back unburned control group, blank back control group. Therefore, puerarin may reduce the nociceptive transmission of burn injury pain mediated by P2X(3) receptor and alleviate P2X(3) receptor involved in hyperalgesia after burn injury in the rats.