the inhibitory effect of bicuculline on the fusiform neurons in the parabrachial nucleus on tonic pain model in rats: role of gabaergic

abstract gaba is a neurotransmitter that is an essential role in the inhibition of pain and gaba signals responsible for chronic pain. parabrachial nucleus is involved in cognitive and emotional aspects of pain. the purpose of this study is to evaluate the inhibitory effect of bicuculline on the fusiform neurons of the parabrachial nucleus on tonic pain model in rats. in this study, 35 male wistar rats weighting approximately 250-300g were divided into four groups: control, 50, 100 and 200 ng/rat. bicycling was injected through the cannula in parabrachial area using a hamilton syringe and polyethylene tubing. formalin tests were used in this study and then fusiform cells were counted using hematoxylin and eosin staining. the fusiform cells in control and the doses of 50 and 100 ng/rat groups did not change significantly, but in the dose of 200ng group, the cells in parabrachial nucleus were significantly reduced (p<0.05). the results of our study indicated that nociceptive stimulation causes changes in the number of fusiform neurons in parabrachial nucleus and it expresses the relationship between function and the number of cells at the highest dose of the antagonist of gaba cells in chronic pain.