Antinociceptive Effects of Botulinum Toxin Type A on Trigeminal Neuropathic Pain.

Previous studies have demonstrated that botulinum toxin type A (BoNT-A) attenuates orofacial nociception. However, there has been no evidence of the participation of the voltage-gated sodium channels (Navs) in the antinociceptive mechanisms of BoNT-A. This study investigated the cellular mechanisms underlying the antinociceptive effects of BoNT-A in a male Sprague-Dawley rat model of trigeminal neuropathic pain produced by malpositioned dental implants. The left mandibular second molar was extracted under anesthesia, followed by a miniature dental implant placement to induce injury to the inferior alveolar nerve. Mechanical allodynia was monitored after subcutaneous injection of BoNT-A at 3, 7, or 12 d after malpositioned dental implant surgery. Subcutaneous injections of 1 or 3 U/kg of BoNT-A on postoperative day 3 significantly attenuated mechanical allodynia, although 0.3 U/kg of BoNT-A did not affect the air-puff threshold. A single injection of 3 U/kg of BoNT-A produced prolonged antiallodynic effects over the entire experimental period. Treatment with BoNT-A on postoperative days 7 and 12, when pain had already been established, also produced prolonged antiallodynic effects. Double treatments with 1 U/kg of BoNT-A produced prolonged, more antiallodynic effects as compared with single treatments. Subcutaneous administration of 3 U/kg of BoNT-A significantly inhibited the upregulation of Nav isoform 1.7 (Nav1.7) expression in the trigeminal ganglion in the nerve-injured animals. These results suggest that antinociceptive effects of BoNT-A are mediated by an inhibition of upregulated Nav1.7 expression in the trigeminal ganglion. BoNT-A is therefore a potential new therapeutic agent for chronic pain control, including neuropathic pain.

Functional properties of tooth pulp neurons responding to thermal stimulation.

The response properties of tooth pulp neurons that respond to noxious thermal stimulation of the dental pulp have been not well-studied. The present study was designed to characterize the response properties of tooth pulp neurons to noxious thermal stimulation of the dental pulp. Experiments were conducted on 25 male ferrets, and heat stimulation was applied by a computer-controlled thermode. Only 15% of tooth pulp neurons (n = 39) responded to noxious thermal stimulation of the teeth. Tooth pulp neurons were found in both the superficial and deep nuclear regions of the subnucleus caudalis (Vc) and in the interface between the nucleus caudalis and interpolaris (Vc/Vi). Thirty-seven neurons had cutaneous receptive fields and were classified as either NS (16) or WDR (21) neurons. Repeated heat stimulation of the dental pulp sensitized and increased the number of electrically evoked potentials of tooth pulp neurons. These results provide evidence that both the Vc and Vc/Vi regions contain neurons that respond to noxious thermal stimulation of the dental pulp, and that these cells may contribute to the sensitization process associated with symptomatic pulpitis.

Early dexamethasone relieves trigeminal neuropathic pain.

The analgesic effects of dexamethasone on neuropathic pain have been controversial. The present study investigated the effects of dexamethasone on mechanical allodynia in rats with mal-positioned dental implants. Under anesthesia, the left mandibular second molar was extracted and replaced by a miniature dental implant to injure the inferior alveolar nerve. Nociceptive behavior was examined on each designated day after surgery. Mal-positioned dental implants significantly decreased air-puff thresholds both ipsilateral and contralateral to the injury site. Distinct mechanical hyperalgesia and cold and thermal hypersensitivity were also observed bilaterally. Daily administration of dexamethasone produced prolonged anti-allodynic effects (25 or 50 mg/kg, i.p.), but failed to reduce mechanical allodynia when it had already been established. Therefore, our findings provide that early treatment with dexamethasone is important in the treatment of nociceptive behavior suggestive of trigeminal neuropathic pain.

Curcumin produces an antihyperalgesic effect via antagonism of TRPV1.

Curcumin has diverse therapeutic effects, such as anti-inflammatory, anti-oxidant, anti-cancer, and antimicrobial activities. The vanilloid moiety of curcumin is considered important for activation of the transient receptor potential vanilloid 1 (TRPV1), which plays an important role in nociception. However, very little is known about the effects of curcumin on nociception. In the present study, we investigated whether the anti-nociceptive effects of curcumin are mediated via TRPV1 by using nociceptive behavioral studies and in vitro whole-cell patch-clamp recordings in the trigeminal system. Subcutaneous injection of capsaicin in the vibrissa pad area of rats induced thermal hyperalgesia. Intraperitoneally administered curcumin blocked capsaicin-induced thermal hyperalgesia in a dose-dependent manner. Whereas curcumin reduced capsaicin-induced currents in a dose-dependent manner in both trigeminal ganglion neurons and TRPV1-expressing HEK 293 cells, curcumin did not affect heat-induced TRPV1 currents. Taken together, our results indicate that curcumin blocks capsaicin-induced TRPV1 activation and thereby inhibits TRPV1-mediated pain hypersensitivity.

Light and electron microscopic analysis of the somata and parent axons innervating the rat upper molar and lower incisor pulp.

The morphology of intradental nerve fibers of permanent teeth and of continuously growing rodent incisors has been studied in detail but little information is available on the parent axons that give rise to these fibers. Here we examined the axons and somata of trigeminal neurons that innervate the rat upper molar and lower incisor pulp using tracing with horseradish peroxidase and light and electron microscopic analysis. The majority (approximately 80%) of the parent axons in the proximal root of the trigeminal ganglion that innervated either molar or incisor pulp were small myelinated fibers (<20 microm(2) cross-sectional area). The remaining approximately 20% of the fibers were almost exclusively large myelinated for the molar pulp and unmyelinated for the incisor pulp. The majority of neuronal somata in the trigeminal ganglion that innervated either molar (48%) or incisor pulp (62%) were medium in size (300-600 microm(2) cross-sectional area). Large somata (>600 microm(2)) constituted 34% and 20% of the trigeminal neurons innervating molar and incisor pulp, respectively, while small somata (<300 microm(2)) constituted 17% of the molar and 18% of the incisor neurons. The present study revealed that the morphology of parent axons of dental primary sensory neurons may differ from that of their intradental branches, and also suggests that the nerve fiber function may be carried out differently in the molar and incisor pulp in the rat.

Intracisternal administration of chemokines facilitated formalin-induced behavioral responses in the orofacial area of freely moving rats.

The present study investigated the effects of intracisternal administration of MCP-1, Rantes or IL-8 on pain transmission in the orofacial area. We also investigated mechanisms of hyperalgesic responses produced by intracisternal administration of IL-8. An orofacial formalin test was employed to assess the effects of chemokines on nociceptive processing. For each animal, the number of behavioral responses and the time spent grooming, rubbing and/or scratching the facial region proximal to the formalin injection site was recorded for nine successive 5-min intervals. Intracisternal administration of MCP-1, Rantes or IL-8 significantly increased formalin-induced scratching behavioral responses in the orofacial area. Intracisternal pretreatment with indomethacin, a non-selective cyclooxygenase inhibitor, did not block IL-8-induced hyperalgesia. Pretreatment with 100 microg propranolol, a non-selective beta-adrenergic receptor antagonist and 50 microg atenolol, a selective beta(1)-adrenergic receptor antagonist, inhibited the number of scratches and the duration of scratching produced by 1 ng of IL-8 injected intracisternally. These results indicate that intracisternal administration of chemokines produce a hyperalgesic response with an orofacial inflammatory pain model and that the IL-8-induced hyperalgesia is mediated by central beta(1)-adrenergic receptor.

Peripheral glutamate receptors participate in interleukin-1beta-induced mechanical allodynia in the orofacial area of rats.

The present study was performed to examine peripheral cytokine-induced mechanical allodynia in the orofacial area and to investigate whether peripheral excitatory amino acids participate in the cytokine-induced mechanical allodynia. Experiments were carried out on male Sprague-Dawley rats. After interleukin-1beta (IL-1beta) was applied subcutaneously to the orofacial area, we examined withdrawal responses produced by air puffs applied to the IL-1beta injection site. The threshold of air puffs that produced withdrawal behavioral responses decreased significantly in a dose-dependent manner after injection of IL-1beta. Pretreatment with an IL-1 receptor antagonist abolished the decrease in the threshold of air puffs. Pretreatment with dl-2-amino-5-phosphonvaleric acid, an N-methyl-d-aspartic acid (NMDA) receptor antagonist, did not affect IL-1beta-induced mechanical allodynia. However, pretreatment with 6,7-dinitroquinoxaline-2,3-dione, a non-NMDA receptor antagonist, abolished the decrease in the threshold of air puffs. These results suggest that peripheral cytokine can produce mechanical allodynia in the orofacial area and that excitatory amino acids can modulate IL-1beta-induced mechanical allodynia via non-NMDA receptors.

Central cyclooxygenase-2 participates in interleukin-1 beta-induced hyperalgesia in the orofacial formalin test of freely moving rats.

The present study was performed to investigate effects of central cyclooxygenase (COX) on interleukin (IL)-1beta-induced hyperalgesia in the orofacial area. Experiments were carried out on 72 male Sprague-Dawley rats weighing 220-280 g. Surgical procedures were performed under pentobarbital sodium. We examined noxious behavioral scratching responses induced by 50 microl of 5% formalin injected subcutaneously into the vibrissa pad without any restraints. The orofacial formalin responses exhibited two distinct phases with early responses (0-10 min) and continuous prolonged responses (11-45 min). Intracisternal injection of 100 pg IL-1beta significantly increased noxious behavioral responses. Pretreatment with indomethacin, a non-selective COX inhibitor, or NS-398, a selective COX-2 inhibitor, blocked IL-1beta-induced hyperalgesic responses. However, pretreatment with SC-560, a selective COX-1 inhibitor, did not change hyperalgesic response to IL-1beta. These data suggest that central IL-1beta modulates the transmission of nociceptive information in the orofacial area and that central COX-2 plays an important role in IL-1beta-induced hyperalgesia.

A case of cutaneous bronchogenic cyst over the left scapula.

Bronchogenic cyst is noted shortly after birth or in early childhood and usually presents as a swelling or draining sinus in the presternal area. Its origin and pathogenesis can be explained as a developmental anomaly of the tracheobronchial buds from the primitive foregut. The patient was a 4-year-old boy with a child-fist-sized soft mass over his left scapula, which had been detected at birth and had been gradually growing. Grossly, it appeared to be a simple cyst with clear mucoid fluid. Histopathological study demonstrated a unilocular cyst composed of ciliated pseudostratified columnar epithelia, interspersed goblet cells, smooth muscles, and mucous glands on the cyst wall, which are features compatible with cutaneous bronchogenic cyst.

Cytoprotective effect of Scutellaria baicalensis in CA1 hippocampal neurons of rats after global cerebral ischemia.

Based on the use of Scutellaria baicalensis for the treatment of stroke in traditional Oriental medicine, the current study was carried out to evaluate neuroprotective effects of S. baicalensis after transient global ischemia using rat 4-vessel occlusion model. Methanol extracts from the dried roots of S. baicalensis (0.1-10 mg/kg) administered intra-peritoneally significantly protected CA1 neurons against 10 min transient forebrain ischemia as demonstrated by measuring the density of neuronal cells stained with Cresyl violet. Methanol extract of S. baicalensis inhibited microglial tumor necrosis factor-alpha (TNF-alpha) and nitric oxide production, and protected PC12 cells from hydrogen peroxide-induced toxicity in vitro.

Microinjection of arginine vasopressin into the central nucleus of amygdala suppressed nociceptive jaw opening reflex in freely moving rats.

This study was performed to examine the antinociceptive effect after microinjection of arginine vasopressin (AVP) into the central nucleus of amygdala. We recorded the jaw opening reflex in freely moving rats. After injection of 0.2 or 0.4 nM AVP into the central nucleus of amygdala, digastric electromyogram (dEMG) was suppressed to 55 +/- 5% or 88 +/- 3 of the control. Artificial cerebrospinal fluid had no effects on the basal dEMG activity. V(1) vasopressin receptor antagonist blocked the suppressive effect produced by microinjection of 0.4 nM AVP from 53 +/- 3 to 81 +/- 3% of the control. However, V(2) vasopressin receptor antagonist did not affect changes in dEMG. We observed dEMG activity after intracerebroventricular injection of naloxone, methysergide, or phentolamine. All drugs did not affect the basal dEMG activity at our dose. Naloxone blocked the suppressive effect of 0.4 nM AVP from 42 +/- 4 to 79 +/- 5% of the control. Methysergide also inhibited the suppression of dEMG from 44 +/- 3 to 83 +/- 6% of the control. However, phentolamine, an alpha-adrenergic receptor antagonist, did not affect the suppression of dEMG. These results indicate AVP in the central nucleus of amygdala has potent analgesic effects in the orofacial area. The antinociception of central AVP seems to be mediated by opioid and serotonergic pathways.

Immortalization of human embryonic fibroblasts by overexpression of c-myc and simian virus 40 large T antigen.

SV40 large T antigen, a viral oncoprotein, is known to immortalize human diploid fibroblast by soaking up cellular RB and p53, but its frequency is extremely low. Additional genetic alteration is necessary for single-step immortalization. We attempted to find out what this alteration is by overexpressing cellular signal mediator genes; c-myc and cyclin D frequently amplified in many cancer cells. Overexpression of cyclin D did not affect the immortalization, but, overexpression of c-myc along with T antigen could immortalize normal human diploid fibroblast. Several cellular markers tested during immortalization process showed that p21, a cyclin-dependent kinase inhibitor and a marker of cellular senescence, disappeared in the life span-extended cells by T antigen and in the immortalized cells by c-myc. p21 was, however, elevated in the senescent cells and in the cells of crisis. Interestingly, p16 was upregulated whenever T antigen is overexpressed. Telomerase activity was also activated only in the immortalized cells. These results suggest that overexpression of c-myc contributes to immortalization of human diploid fibroblast by activating telomerase activity and suppressing p21 activity.

Central-amygdaloid carbachol suppressed nociceptive jaw opening reflex in freely moving rats.

1. Experiments were carried out in rats with stimulating electrodes implanted in the dental pulp, recording electrodes inserted into the anterior digastric muscle, and indwelling cannula implanted in the central amygdaloid nucleus and the cisterna magna area. 2. Injection of 4.4 nM and 8.8 nM carbachol into the central amygdaloid nucleus suppressed digastric electromyogram (dEMG) to 81 +/- 8% and 47 +/- 9% of the control, respectively. 3. Atropine, a muscarinic receptor antagonist, blocked the suppression of dEMG in response to the administration of 8.8 nM carbachol into the amygdala. However, a mecamylamine, a nicotinic receptor antagonist, did not affect changes in dEMG. 4. Intracisternal naloxone, an opioid receptor antagonist, reduced the suppression of dEMG from 47 +/- 10 to 72 +/- 12% of the control. 5. Intracisternal methysergide, a serotonin receptor antagonist, also reduced the suppression of dEMG from 50 +/- 9 to 78 +/- 9% of the control. 6. The carbachol-induced antinociception from the central amygdaloid nucleus was attributed to opioid and serotonergic descending inhibitory influences on nociceptive pathways.

Pathways by which SES and ethnicity influence cardiovascular disease risk factors.

Little is known about pathways by which socioeconomic status (SES) translates into individual differences in cardiovascular disease (CVD) risk factors. Because the socioeconomic structure is not the same for all ethnic subgroups, the pathways that lead to the development of CVD risk factors may vary by both SES and ethnicity. We used data from a large national survey to examine the independent associations of two indicators of SES (education and income) and ethnicity with six primary CVD risk factors. We then used data on smoking that reflected a temporal sequence to examine the extent to which SES and ethnicity influenced smoking at three different time points, from smoking onset, to a serious quit attempt, to successful quitting. These analyses provide an understanding of the relationships between SES, ethnicity, and CVD risk factors and suggest that if the timing, focus, and content of intervention programs take pathways into account they will result in more successful outcomes.

Determinants of cholesterol screening and treatment patterns. Insights for decision-makers.

BACKGROUND: Adult cholesterol screening and treatment policies by the National Cholesterol Education Program recommend that physicians screen all adults aged > 20 [corrected]. On the other hand, the American College of Physicians recommends that healthy young adult men aged > 35 and premenopausal women aged > 45 not be screened due to concerns about the cost of and health risks associated with overuse of pharmacologic therapy in lieu of lifestyle modification. OBJECTIVES: The objectives of this study were to determine the type of treatment (lifestyle vs. pharmacologic) that physicians actually prescribe for individuals screened for elevated cholesterol. METHODS: Self-report data were derived from the 1989-1990 cross-sectional survey of the Stanford Five-City Project on 1,883 Latino and Anglo men and women aged 20 to 74 years of age. A four-stage sequential design was conducted using multiple stepwise regression analyses with a significance cutpoint of P < .01. RESULTS: Young adult men and women were significantly less likely to report ever having been screened (OR 1.02; 95% CI 1.07-1.09). Individuals of low socioeconomic status (SES) were also significantly less likely to report ever being screened (OR, 1.12; CI, 1.08-1.16), as were Latino men and women, regardless of age (OR 1.57; CI, 1.14-2.18). There were no significant differences in the pattern of physician care utilization among low SES or Latino individuals during the previous 12-month period. Among those under physician care to lower cholesterol, young adults were more likely to be prescribed lifestyle modification (OR, 0.95; CI, 0.92-0.98). CONCLUSIONS: Our results suggest that although young adults are less likely to be screened, if screened they are more likely to be prescribed lifestyle modification than pharmacologic treatment for elevated cholesterol. The lower prevalence of screening among low SES and Latino individuals suggests the need for policy discussions to reduce these disparities.

Ethnic and socioeconomic differences in cardiovascular disease risk factors: findings for women from the Third National Health and Nutrition Examination Survey, 1988-1994.

CONTEXT: Cardiovascular disease (CVD) risk factors are higher among ethnic minority women than among white women in the United States. However, because ethnic minority women are disproportionately poor, socioeconomic status (SES) may substantially explain these risk factor differences. OBJECTIVE: To determine whether differences in CVD risk factors by ethnicity could be attributed to differences in SES. DESIGN: Third National Health and Nutrition Examination Survey conducted between 1988 and 1994. SETTING: Eighty-nine mobile examination centers. PARTICIPANTS: A total of 1762 black, 1481 Mexican American, and 2023 white women, aged 25 to 64 years, who completed both the home questionnaire and medical examination. MAIN OUTCOME MEASURES: Ethnicity and years of education (SES) in relation to systolic blood pressure, cigarette smoking, body mass index (BMI, a measure of weight in kilograms divided by the square of height in meters), physical inactivity, non-high-density lipoprotein cholesterol (non-HDL-C [the difference between total cholesterol and HDL-C]), and non-insulin-dependent diabetes mellitus. RESULTS: As expected, most CVD risk factors were higher among ethnic minority women than among white women. After adjusting for years of education, highly significant differences in blood pressure, BMI, physical inactivity, and diabetes remained for both black and Mexican American women compared with white women (P<.001). In addition, women of lower SES from each of the 3 ethnic groups had significantly higher prevalences of smoking and physical inactivity and higher levels of BMI and non-HDL-C than women of higher SES (P<.001). CONCLUSIONS: These findings provide the greatest evidence to date of higher CVD risk factors among black and Mexican American women than among white women of comparable SES. The striking differences by both ethnicity and SES underscore the critical need to improve screening, early detection, and treatment of CVD-related conditions for black and Mexican American women, as well as for women of lower SES in all ethnic groups.

Central NO is involved in the antinociceptive action of intracisternal antidepressants in freely moving rats.

The present study was performed to examine the central effects of antidepressants on nociceptive jaw opening reflex after intracisternal injection. we also investigated the mechanisms of central antinociceptive action of intracisternal antidepressants. We recorded the jaw opening reflex in freely moving rats and chose to administer antidepressants intracisternally in order to eliminate the effects of anesthetic agents on the pain assessment and evaluate the importance of the spinal site of action of antidepressants. After intracisternal injection of 15 microg imipramine, digastric electromyogram (dEMG) was decreased to 76+/-6% of the control. Intracisternal administration of 30 microg desipramine, nortriptyline or imipramine suppressed dEMG remarkably to 48+/-2, 27+/-8, or 25+/-5% of the control, respectively. The suppression of dEMG was maintained for 50 min. L-NG-Nitroarginine methyl ester (NAME) blocked the suppression of dEMG from 32+/-2 to 81+/-5% of the control. These results indicate that antidepressants produce antinociception through central mechanisms in the orofacial area. The central NO pathway seems to be involved in the antinociception of intracisternal antidepressants at supraspinal sites.

The effects of marital transitions on changes in physical activity: results from a 10-year community study.

The potential effects of making a marital transition on subsequent physical activity were evaluated across a ten-year period in a population-based sample of 302 women and 256 men ages 25 to 75 years. Subjects completed a structured interview at five timepoints throughout the ten-year period during which they reported on their physical activity level as well as marital status. The transition from a married to a single state did not affect physical activity relative to remaining married when analyses of either slopes or mean values were used. In contrast, the transition from a single to a married state resulted in significant positive changes in physical activity relative to remaining single throughout the study period when physical activity slopes, though not means, were compared. The results suggest that marriage may potentially set the stage for natural changes in physical activity that could be capitalized on through appropriate intervention, but additional research is needed to verify this in light of the inconsistent pattern of findings.

Smoking initiation and cessation in Norway and the United States: a comparison of two cross-sectional surveys.

PURPOSE: Smoking prevalence in a population is affected by the proportion of adolescents who start to smoke, and the proportion of smokers who quit. Smoking prevalence has declined linearly in the US and in the state of California during the last 2 decades. Due to an increase in female smoking, the Norwegian smoking prevalence has been stable at around 35% since 1980, while other European countries have seen reductions of at least 10 percentage points. METHODS: We compared data from two cross-sectional studies; one from Western and Central Norway (n = 5014), and one from Northern California (Stanford Five-City Project) (n = 2189). RESULTS: Norwegian smoking prevalence figures were significantly higher in all age-sex groups younger than 60 years. The proportion of former smokers was not different, suggesting that the differences between the samples are due to higher smoking initiation in Norway. University education was the most potent covariate of both ever-smoking and current smoking across samples and gender. Amount of physical exercise was associated with never-smoking in Norway, but not in the US. Having smoking parents was related to ever-smoking in women but not in men in both samples. Smoking parents also was related to current smoking in Norway but not in the US. IMPLICATIONS: Norway should increase efforts to prevent smoking initiation among adolescents, and especially among girls.

Craniofacial skeletal fixation using biodegradable plates and cyanoacrylate glue.

This study examined the feasibility of fixation of craniofacial bone using Lactosorb biodegradable plates adhered to bone with butyl-2-cyanoacrylate adhesive (Histoacryl) in a pig. The stability and bone-healing characteristics of this rigid fixation method were studied and compared with standard rigid fixation using metal plates and screws on osteotomy sites in the frontal bones and infraorbital rims. Rectangular osteotomies (2.0 x 3.0 cm) were performed on the right and left sides of the frontal bone and wedge-shaped osteotomies (1.5 x 1.7 cm) were made on the left and right infraorbital rims in seven Yorkshire pigs. Metal plates were applied with screws to the osteotomies on one side, and the other side was fixed with a biodegradable plate and butyl-2-cyanoacrylate. The animals were sacrificed at 8 weeks, and both sides were compared biomechanically and histologically. Radiographic, biomechanical, and histologic analyses were performed to evaluate skeletal stability, contour, accurate positioning of bony fragments, bone healing, and maximum torque to failure of the repair sites. Clinical and radiographic observations demonstrated stability of the bone fragments without any evidence of displacement. According to Student's t test for paired data, no statistical difference was found in the maximum torque to failure of fragments fixed with biodegradable plates and glue compared with those fixed with metal plates and screws (p > 0.05), whether or not a gap existed at the osteosynthesis site. Although the sample size was small, no differences were noted between the two types of treatment groups. This study demonstrates that rigid internal fixation of osteotomized cranial bone fragments using biodegradable plates and butyl-2-cyanoacrylate is as effective as metal plate and screw fixation in this animal model.