Effect of Administration of Lidocaine at Body Temperature on Anesthesia Success in Rodent Model: A Behavioral and Electrophysiology Study.

Introduction: Success in anesthesia administration relieves the perception of pain during surgery. Lidocaine is the most commonly used local anesthetic agent in clinical medicine. Moreover, anesthetic agents' temperature changes can influence cell membrane permeability. Here, the effectiveness of different temperatures of Lidocaine (Lid.) on anesthesia success rate has been investigated in rats. Methods: Wistar male rats were pretreated by fast injection of lidocaine or saline into the hind paw or intradermal cheek at Room Temperature (RT) and Body Temperature (BT) (22°C and 37°C, respectively). Then, rat behaviors were evaluated by formalin-induced hind paw pain and orofacial pain tests, respectively. Moreover, using a single-unit recording technique, the spontaneous activity of the marginal nerve was recorded at room temperature in the RT-Lid. and BT-Lid. groups. Results: Data analysis revealed that lidocaine had significant antinociceptive effects in both the BT-Lid. and RT-Lid. groups compared to the control groups (P<0.05). Also, the number of spikes in the BT-Lid. and RT-Lid. groups were significantly lower than their baselines (P<0.05). However, lidocaine at body temperature decreased the total time spent licking the hind paw, the number of lip rubbings, and the number of spikes firing by about 10%-15% compared to room temperature. Conclusion: In both behavioral and neural levels of the study, our results showed that an increase in the temperature of lidocaine toward body temperature could increase anesthesia success rate compared to administration of lidocaine at room temperature. These findings can be considered in the treatment of patients. Highlights: Lidocaine at body temperature acted better than room temperature on pain control in the formalin-induced hind paw test.Lidocaine at body temperature acted better than room temperature on pain control in the orofacial formalin test.Lidocaine with different temperatures decreased the firing rate of the marginal nerve. Plain Language Summary: Pain is defined as an unpleasant experience caused by tissue damage or fear of injury. During anesthetic injection in dentistry, pain has long been one of the problems of dentists. Studies have shown that one out of every three people is worried about going to dentistry, and one of four dental patients is afraid of injections. The fear of a patient in one of twenty patients is so much that interferes with dental treatment which consequently leads to stress when you visit the dentist, results in less oral hygiene and reduces the number of referrals. Lidocaine is the most commonly used local anesthetic agent in clinical medicine. Here, the effectiveness of different temperatures of lidocaine on anesthesia success rate in rats has been investigated in rats. The present study showed that warming the lidocaine cartridges to 37°C increased anesthesia success compared to anesthesia-induced at room temperature in both behavioral and neural levels of the study. Accordingly, a warmed anesthetic cartridge could be used to control pain by increasing the success rate during dental injection and designed a new animal model study for further investigation in comparing other anesthesia drugs.

Serum biochemical parameters following heroin withdrawal: an exploratory study.

BACKGROUND: Long-term consumption of opioid compounds, even after withdrawal, affects serum biochemical parameters. Investigating these alterations is a new approach in substance abuse studies. METHOD: This study investigated clinical laboratory results in men who are currently active, recently abstinent and non-heroin users. Participants (N = 240) of this matched cohort study included heroin dependent men referred for abstinence treatment, volunteer men who did not abuse opioids matched for age, sex, body mass index, and educational level (control group). The groups were further sub-divided for analysis into (a) continuous heroin users for more than 2 years (N = 70), the dependent group; (b) heroin abusers with 1 month abstinence period (N = 70), identified as ex-heroin dependents; and (c) a matched, non-dependent control group (N = 100). All participants were tested for fasting blood sugar (FBS), sodium, potassium, calcium, uric acid (UA), blood urea nitrogen (BUN), creatinine, total cholesterol, triglycerides (TGs), total protein, fibrinogen, and prothrombin. RESULTS: Compared to the control group, ex-heroin dependents showed decreased FBS and significantly higher sodium, creatinine, and cholesterol levels. Compared to the heroin dependent group, the ex-heroin dependents showed significant differences in FBS, sodium, calcium, creatinine, UA, and thrombin time. No significant differences were noted between ex-heroin dependents and controls in potassium, calcium, UA, BUN, TGs, total protein, and thrombin time. CONCLUSION: These results demonstrate altered laboratory markers in long-term heroin dependents as well as ex-heroin dependents and suggest the need for further identification, population distribution, and etiological understanding of these biomarkers in individuals who have abused heroin.

Effects of electrical stimulation of dorsal raphe nucleus on neuronal response properties of barrel cortex layer IV neurons following long-term sensory deprivation.

OBJECTIVE: To evaluate the effect of electrical stimulation of dorsal raphe nucleus (DRN) on response properties of layer IV barrel cortex neurons following long-term sensory deprivation. METHODS: Male Wistar rats were divided into sensory-deprived (SD) and control (unplucked) groups. In SD group, all vibrissae except the D2 vibrissa were plucked on postnatal day one, and kept plucked for a period of 60 d. After that, whisker regrowth was allowed for 8-10 d. The D2 principal whisker (PW) and the D1 adjacent whisker (AW) were either deflected singly or both deflected in a serial order that the AW was deflected 20 ms before PW deflection for assessing lateral inhibition, and neuronal responses were recorded from layer IV of the D2 barrel cortex. DRN was electrically stimulated at inter-stimulus intervals (ISIs) ranging from 0 to 800 ms before whisker deflection. RESULTS: PW-evoked responses increased in the SD group with DRN electrical stimulation at ISIs of 50 ms and 100 ms, whereas AW-evoked responses increased at ISI of 800 ms in both groups. Whisker plucking before DRN stimulation could enhance the responsiveness of barrel cortex neurons to PW deflection and decrease the responsiveness to AW deflection. DRN electrical stimulation significantly reduced this difference only in PW-evoked responses between groups. Besides, no DRN stimulation-related changes in response latency were observed following PW or AW deflection in either group. Moreover, condition test (CT) ratio increased in SD rats, while DRN stimulation did not affect the CT ratio in either group. There was no obvious change in 5-HT(2A) receptor protein density in barrel cortex between SD and control groups. CONCLUSION: These results suggest that DRN electrical stimulation can modulate information processing in the SD barrel cortex.

A review on hematological factors in opioid-dependent people (opium and heroin) after the withdrawal period.

BACKGROUND: Long-term use of opioids has acute effects on homeostasis of the body. Discovering the impacts of opioids on hematological parameters of narcotics withdrawal and dependents blood may be helpful in recognizing the homeostasis condition of their body for the useful treatment. METHODS: In this study a cross-sectional method was applied. The abusers of opium and heroin for more than two consecutive years were considered as opium and heroin dependent groups, respectively. The dependent people, who passed the 1-month withdrawal period, entered the study as opium and heroin withdrawal groups. In this study, hematological factors of heroin and opium dependent and withdrawal groups were investigated. FINDINGS: The RBC count remained unchanged in all groups. The WBC count had a significant increase in opium dependent group but in heroin dependent group and withdrawal group there was no significant difference. HGB level had a significant increase only in opium and heroin withdrawal groups. The percentage of HCT had a significant increase in all groups. The MCV increased in heroin and opium dependent groups. MCH level increased significantly in heroin and opium withdrawal groups. MCHC level had a significant increase in all groups. Neutrophil and lymphocyte counts in heroin and opium addicted groups significantly decreased. Platelet, neutrophil and monocyte counts significantly increased in opium dependent group. Monocyte countshowed a significant reduction in heroin withdrawal group. Eosinophil count showed no difference in any of the groups. CONCLUSION: The current study indicated that not only the chronic and long-term use of opium and heroin, also withdrawal of addicted people could change hematological parameters related to human serum.