The effect of GABA A receptor antagonist - bicucullin - administration on the number of multiform neurons in the brain parabrachial nucleus due to pain induction of adult male rats

A lot of biological investigations are aimed to find pain decreasing or relieving substances that appear in various diseases. Parabrachial nucleus plays an important role in cognitive and emotional aspects of pain. The present study was designed to evaluate the inhibitory effect of bicuculine- as a GABA A receptor antagonist- on the number of multiform neurons in Parabrachial region of adult male rats in tonic pain model. This experimental study was carried out on 40 Wistar male rats. Based on the pain induction, the animals were divided into 8 groups (n=5). Bicuculine was administrated in doses of 50, 100, and 200 ng/rat. Using stereotaxic method, Bicuculine was administrated to the rats` brain parabrachial area. The present study utilized Formalin test as a standard method for pain stimulations. Thereafter, Gimsa staining method was applied for histological determination of multiform cells. The obtained data was analyzed using statistical testsincluding Student-t and one-way ANOVA. Our data showed no significant changes in the number of multiform cells in Parabrachial nucleus between the animals administrated by bicuculine at the dose of 50 AWT IMAGE compared with the controls (P>0.05). Nevertheless, the number of these cells was decreased significantly in the animals administrated by bicuculine at the doses of 100 and 200 AWT IMAGE when compared to the controls (p<0.05). It was found that nociceptive stimulations cause changes in the number of multiform neurons in para- brachial nucleus. Nevertheless, higher dose administration of GABA A receptor antagonist has preventive effects on neuronal dysmorphogenesis at this brain area.