The effect of capsaicin on expression patterns of CGRP in trigeminal ganglion and trigeminal nucleus caudalis following experimental tooth movement in rats

ABSTRACT Objectives The aim of this study was to explore the effect of capsaicin on expression patterns of calcitonin gene-related peptide (CGRP) in the trigeminal ganglion (TG) and trigeminal subnucleus caudalis (Vc) following experimental tooth movement. Material and Methods Male Sprague-Dawley rats were used in this study and divided into small-dose capsaicin+force group, large-dose capsaicin+force group, saline+force group, and no force group. Closed coil springs were used to mimic orthodontic forces in all groups except for the no force group, in which springs were inactivated. Capsaicin and saline were injected into periodontal tissues. Rats were euthanized at 0 h, 12 h, 1 d, 3 d, 5 d, and 7 d following experimental tooth movement. Then, TG and Vc were obtained for immunohistochemical staining and western blotting against CGRP. Results Immunohistochemical results indicated that CGRP positive neurons were located in the TG, and CGRP immunoreactive fibers were distributed in the Vc. Immunohistochemical semiquantitative analysis and western blotting analysis demonstrated that CGRP expression levels both in TG and Vc were elevated at 12 h, 1 d, 3 d, 5 d, and 7 d in the saline + force group. However, both small-dose and large-dose capsaicin could decrease CGRP expression in TG and Vc at 1 d and 3 d following experimental tooth movement, as compared with the saline + force group. Conclusions These results suggest that capsaicin could regulate CGRP expression in TG and Vc following experimental tooth movement in rats.

Difference of the Naltrexone's Effects in Social Drinkers by Spicy Food Preference

The purpose of this study was to investigate the differences in subjective acute effects of alcohol and naltrexone among those who prefer spicy food to varying degrees. Acute biphasic alcohol effects scale (BAES), visual analogue scale for craving (VAS-C), blood alcohol concentration (BAC) and food preference scale were measured in 26 men. Repeated measures ANOVA (2 preference groupsx4 time blocks) on the stimulative subscale of BAES revealed a significant group by block interaction in naltrexone condition (N+) (P<0.001), but not in non-naltrexone condition (N-). Furthermore, repeated measures ANOVA (2 drug groupsx4 time blocks) on the stimulative subscale of BAES revealed a significant group by block interaction in strong preference for spicy food (SP) (P<0.001), but not in lesser preference for spicy food (LP). The paired t-test revealed that significant suppression of the stimulative subscale of BAES was observed at 15 min (P<0.001) and 30 min (P<0.001) after drinking when N+ compared with N- in SP. For those who prefer spicy food, the stimulative effect of acute alcohol administration was suppressed by naltrexone. This result suggests that the effect of naltrexone may vary according to spicy food preference.

Vasosensory responses elicited by Indian red scorpion venom last longer than capsaicin-induced responses.

The present study was conducted to compare the time-related cardiorespiratory changes occurring after the injection of Mesobuthus tamulus (BT; 1 mg/kg) venom and capsaicin (1.2 ng/kg) in the peripheral end of femoral artery in urethane anaesthetised rats. Blood pressure (BP), electrocardiogram (for heart rate; HR) and respiratory movements were recorded for 60 min after venom/capsaicin intra-arterially. Minute ventilation (MV) was computed by using appropriate calibrations. After intraarterial injection of BT venom, there was immediate (within 2 sec) increase in respiratory rate (RR) and MV which reached to 40% within 30 sec, followed by a 40% decrease in RR without any change in MV. Further, there was sustained increase in RR (50%) and MV (65%) up to 60 min. The BP began to increase at 40 sec, peaking at 5 min (50%) and remained above the initial level up to 60 min. The bradycardiac response began after 5 min which peaked (50% of the initial) at 25 min and remained at that level up to 60 min. In capsaicin treated group, there was immediate hyperventilatory (increase in RR and MV) changes within 2 sec which returned to the initial level within 2 min and remained at that level up to 60 min. The capsaicin-induced hypotensive response began within 5 sec which returned to the initial level by 5 min and remained at that level throughout. Capsaicin did not produce any change in HR. These observations suggest that intraarterial injection of BT venom produces prolonged cardiorespiratory alterations as compared to the capsaicin-induced responses.