The effects of acute restraint stress on nociceptive responses evoked by the injection of formalin into the temporomandibular joint of female rats.

The temporomandibular joint (TMJ) formalin test was used to evaluate the effects of acute restraint stress on the nociceptive behavioral responses of female rats during proestrus and estrus phases of the estrous cycle. Rats were subjected to one session of restraint stress (15, 30 min or 1 h). They were then either immediately killed to allow the collection of blood for hormonal radioimmunoassay determinations or subjected to TMJ formalin test to evaluate nociception. All stress protocols significantly raised the plasma concentrations of corticosterone. The performance of rats subjected to 15 and 30 min of restraint stress was similar to that of control rats, whereas rats that were stressed for 1 h showed a decrease in nociceptive responses, during both proestrus and estrus phases. The stress-induced analgesia (SIA) was greater in the proestrus phase. To evaluate the role of kappa-opioid receptors, the selective receptor kappa-opioid antagonist nor-binaltorphimine (nor-BNI; 200 microg or saline) was injected into the TMJ 24 h prior to the 1 h stress period and the TMJ formalin test. The local administration of nor-BNI partially reversed the SIA during the proestrus phase. These findings suggest that (1) acute stress for 1 h can produce analgesia both during proestrus and estrus phases; this effect is greater during the proestrus phase and (2) kappa-opioid receptor activation is involved in the SIA observed in the proestrus phase.

Effects of short- and long-term celecoxib on orthodontic tooth movement.

OBJECTIVE: To test the hypothesis that short- and long-term celecoxib administration has no effect on orthodontic tooth movement. MATERIALS AND METHODS: Male Wistar rats were submitted to short- (3 days) and long-term (14 days) celecoxib administration, while the respective control groups received equivolumetric saline intraperitoneal injections. The upper left first molars of all rats were moved mesially for 14 days by a fixed orthodontic appliance exerting 50 g force upon insertion. After the experimental period, tooth movement was quantified and tissues around the first molar were processed for tartrate-resistant acid phosphatase (TRAP) histochemistry. The amount of tooth movement and the number of TRAP-positive cells on the alveolar bone surface were evaluated. RESULTS: The amount of tooth movement was significantly reduced in rats submitted to short- and long-term celecoxib administration, while the number of osteoclasts on the alveolar bone did not differ between the four groups studied. CONCLUSIONS: The hypothesis is rejected. Although celecoxib administration did not affect the number of osteoclasts, the osteoclast activity might be reduced, which could explain the inhibition of tooth movement observed in the celecoxib-treated animals. These results indicate that orthodontists should be aware of patients under short- and long-term therapy with celecoxib.

The effects of systemic stress on orthodontic tooth movement.

OBJECTIVES: To determine if systemic stress affects the biological reactions occurring during orthodontic tooth movement. METHODS: Four groups of male 10 week-old Wistar rats were used. Group A animals (N=10) were restrained for one hour per day for 40 days; Group B animals (N=10) were restrained for one hour per day for three days; Group C (N=10) and Group D (N=8) animals were unrestrained. The upper left first molars in the rats in Groups A (long-term stress), B (short-term stress) and C (control) were moved mesially during the last 14 days of the experiment. The animals in Group D (N=8) were used for body weight and hormonal dosage comparisons only. They were not subjected to any stress and did not have appliances fitted. All animals were killed at 18 weeks of age and blood collected for measurement of plasma corticosterone. Tooth movement was measured with an electronic caliper. The right and left hemi-maxillae of five rats from each group were removed and the number of tartrate-resistant acid phosphatase (TRAP) positive cells, defined as osteoclasts, adjacent to the mesial roots of the upper first molars counted. The contralateral side in each animal served as the control (split-mouth design). RESULTS: Corticosterone levels were significantly higher in the stressed groups (Groups A and B) than in the control group (Group C). Tooth movement was significantly greater in Group A (long-term stress) compared with Group B (short-term stress) and Group C (control), which did not differ from each other. There were significantly more osteoclasts in the long-term stress group than in the short-term stress and control groups. CONCLUSION: Persistent systemic stress increases bone resorption during orthodontic tooth movement. Systemic stress may affect the rate of tooth movement during orthodontic treatment.

Involvement of peripheral TRPV1 in TMJ hyperalgesia induced by ethanol withdrawal.

Ethanol withdrawal increases nociception after the injection of formalin into the rat's temporomandibular joint (TMJ). Little is known about the neurological basis for hyperalgesia induced by ethanol withdrawal, but it has been reported that ethanol can potentiate the response of transient receptor potential vanilloid receptor-1 (TRPV1) in superficial tissues. The present study was designed to test the hypothesis that peripheral TRPV1 could be involved on nociceptive behavioral responses induced by the injection of formalin into the TMJ region of rats exposed to chronic ethanol administration and ethanol withdrawal. Behavioral hyperalgesia was verified 12 h after ethanol withdrawal in rats that drank an ethanol solution (6.5%) for 10 days. In another group submitted to the same ethanol regimen, the selective vanilloid receptor antagonist capsazepine (300, 600 or 1200 microg/25 microl) or an equal volume of vehicle were injected into the TMJ regions 30 min before the TMJ formalin test. The local injections of capsazepine reduced the increased nociceptive responses induced by ethanol withdrawal. The effect of capsazepine on rats that did not drink ethanol was not significant. These results indicate that the peripheral TRPV1 can contribute to the hyperalgesia induced by ethanol withdrawal on deep pain conditions.

Peripheral sympathetic component of the temporomandibular joint inflammatory pain in rats.

UNLABELLED: The aim of this study was to further validate our carrageenan-induced temporomandibular joint (TMJ) inflammatory hyperalgesia model in rats by showing that administration of indomethacin before the initiation of inflammation would diminish the TMJ hyperalgesia. Using this model, we investigated whether norepinephrine and local beta-adrenoceptors contribute to the development of inflammatory TMJ hyperalgesia. Carrageenan-induced TMJ hyperalgesia was assessed by measuring the behavioral nociceptive responses, such as rubbing the orofacial region and flinching the head, induced by the injection of a low dose of 5-hydroxytryptamine into the TMJ sensitized 1 h before by a TMJ injection of carrageenan. Blockade of prostaglandin synthesis by indomethacin prior to initiation of inflammation by carrageenan significantly attenuated the TMJ hyperalgesia. The guanethidine depletion of norepinephrine or the blockade of beta(2)but not the blockade of the beta(1)-adrenoceptor by the selective adrenoceptor antagonists ICI 118.55 and atenolol, respectively, significantly reduced carrageenan-induced TMJ hyperalgesia. In the present study, we further validated our carrageenan-induced TMJ hyperalgesia model to study the mechanisms involved in inflammatory TMJ hyperalgesia and to test the analgesic effect of different types of peripheral analgesics. We also demonstrated that norepinephrine released at the site of injury contributes to the development of the inflammatory TMJ hyperalgesia by the activation of beta(2)-adrenoceptors. PERSPECTIVE: The findings that local sympathomimetic amines contribute to the inflammatory TMJ hyperalgesia by activating beta(2)-adrenoceptors may be relevant to clinical TMJ inflammatory pain states less sensitive to nonsteroidal anti-inflammatory drugs.

Nociception- and anxiety-like behavior in rats submitted to different periods of restraint stress.

The aim of this study was to evaluate the effect of acute, sub-chronic and chronic stress on nociception induced by formalin injection in rats' temporomandibular joint (TMJ). It was evaluated the relation between blood levels of adrenocorticotropin, corticosterone, the levels of anxiety and nociceptive responses recorded after different stress protocols. Animals were initially submitted to acute restraint stress (15; 30 min and 1 h), or exposed to sub-chronic (3 days-1 h/day) or chronic stress (40 days-1 h/day). Then, animals were (1) killed immediately to collect blood for hormonal determinations; or (2) submitted to the elevated plus-maze to evaluate anxiety; or (3) submitted to the TMJ formalin test to evaluate nociception. It was also evaluated the role of serotoninergic and opioid systems in nociceptive changes induced by stress. For this, the serotonin-selective reuptake inhibitor (fluoxetine 10 mg/kg) and the opioid agonist (morphine 1-5 mg/kg) were administered before the nociception test. All stress protocols significantly raised the levels of ACTH or corticosterone, as well as the anxiety behavior. In relation to nociception, the chronic stressed animals showed an increase in nociceptive responses (hyperalgesia). In this group, there was a reduction in the morphine analgesic effects, suggesting dysfunction in the endogenous opioid system. Fluoxetine had an analgesic effect in both stressed and control groups, although this effect was more evident in the stressed group. It was concluded that stress-induced hyperalgesia may result from changes in the serotoninergic and opioid systems, which can explain, at least in part, the important link between stress and orofacial pain.

Evidence for the involvement of endogenous ATP and P2X receptors in TMJ pain.

Evidence is accumulating which supports a role for ATP in the initiation of pain by acting on P2X receptors expressed on nociceptive afferent nerve terminals. To investigate whether these receptors play a role in temporomandibular (TMJ) pain, we studied the presence of functional P2X receptors in rat TMJ by examining the nociceptive behavioral response to the application of the selective P2X receptor agonist alpha,beta-methylene ATP (alpha,beta-meATP) into the TMJ region of rat. The involvement of endogenous ATP in the development of TMJ inflammatory hyperalgesia was also determined by evaluating the effect of the general P2 receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) on carrageenan-induced TMJ inflammatory hyperalgesia. Application of alpha,beta-meATP into the TMJ region of rats produced significant nociceptive responses that were significantly reduced by the co-application of lidocaine N-ethyl bromide quaternary salt, QX-314, (2%) or of the P2 receptor antagonist PPADS. Co-application of PPADS with carrageenan into the TMJ significantly reduced inflammatory hyperalgesia. The results indicate that functional P2X receptors are present in the TMJ and suggest that endogenous ATP may play a role in TMJ inflammatory pain mechanisms possibly by acting primarily in these receptors.

Peripheral effect of a kappa opioid receptor antagonist on nociception evoked by formalin injected in TMJ of pregnant rats.

The effect of sex hormones on orofacial pain modulation is poorly understood. Therefore, this study aimed to investigate the effect of hormonal changes as a result of pregnancy, as well as that of the kappa (kappa) opioid receptor antagonist on female rats' sensitivity to the temporomandibular joint (TMJ) formalin test. Initially, female rats at estrus and pregnant females on day 19 of pregnancy received a 50 microl formalin (1.5%) injection in the right TMJ. The pregnant females showed a reduction in nociceptive responses to the TMJ formalin test when compared with those at estrus. Then, the selective kappa-opioid receptor antagonist nor-Binaltorphimine (nor-BNI), was co-administered with the formalin. Next, additional groups received the kappa (200 microg) receptor antagonist or 0.9% NaCl 24 hours prior to the periarticular injection of formalin. Co-administration of nor-BNI with formalin into the TMJ region had no significant effect. The pre-injection of selective kappa-opioid receptor antagonist, nor-BNI, significantly enhanced the nociceptive behavioral responses in pregnant females. When applied in the contralateral TMJ, nor-BNI did not affect the magnitude of the nociceptive response induced by formalin. It can be concluded that: 1) The increase of the sex hormone levels, as result of pregnancy, induces a reduction of nociceptive behavioral responses to the TMJ formalin test; 2) the peripheral kappa opioid receptor activation, by endogenous opioid agonists release, is involved in the antinociception to TMJ formalin test, induced by pregnancy.

The effects of restraint stress on nociceptive responses induced by formalin injected in rat's TMJ.

It has been reported that stress can alter nociception from superficial tissues, such as skin and subcutaneous region. However, the influence of stress on an experimental deep nociception model is not understood. In this study, the temporomandibular joint (TMJ) formalin test was used to evaluate the effects of acute and chronic restraint stress on nociceptive responses in rats. Animals were initially submitted to one session of acute restraint stress (1 h) or exposed to chronic stress (40 days-1 h/day). Then, animals were killed immediately to collect blood for hormonal determinations by radioimmunoassay, or submitted to the TMJ formalin test to evaluate nociception. Rats submitted to acute restraint presented a performance similar to unstressed controls in the TMJ formalin test, whereas chronically stressed rats showed an increase in nociceptive responses. After 40 days of restraint, morphine was injected i.p. (1, 5 mg/kg or saline). The stressed rats displayed decreased morphine effects on nociception compared to unstressed controls. These findings suggest that repeated stress can produce hyperalgesia, which is, at least in part, due to alterations in the activity of opioid systems. This model may help elucidate the underlying neural mechanisms that mediate the effects of repeated stress on orofacial pain.

Effects of ethanol on deep pain evoked by formalin injected in TMJ of rat.

It has been reported that ethanol can alter nociceptive sensitivity from superficial tissues, such as skin and subcutaneous region. However, the influence of ethanol on deep pain conditions is not understood. The aim of this study was to demonstrate the acute, chronic and ethanol withdrawal effects on nociceptive behavioral responses induced by the injection of formalin into the temporomandibular joint (TMJ) region of rats. In experiment 1, rats were injected with ethanol (2,5 g/Kg, i.p.) or an equal volume of saline 15 min before the administration of formalin (1.5%) into the TMJ. Rats pretreated with ethanol showed a decrease in nociceptive behavioral responses. In experiment 2, rats were given an ethanol solution (6.5%) or tap water to drink for 4 and 10 days. On day 4, the animals (ethanol group) showed amounts of analgesia when submitted to the TMJ formalin test. Tolerance to the antinociceptive effects was observed on day 10. Behavioral hyperalgesia was verified 12 hr after withdrawal in another group that drank ethanol for 10 days. These results show that ethanol can affect the nociceptive responses related to deep pain evoked by the TMJ formalin test.

Influence of sex on temporomandibular disorder pain: a review of occurrence and development

Aim: The aim of this study was to develop a narrative literature review using international research to present the influence of sex on occurrence and development of temporomandibular disorder (TMD) pain. Methods: The data sources were computer-based searches in PubMed between 1987 and Feb 2008 using appropriate keywords. For inclusion in this review, articles had to meet the following criteria: be written in English; include human and nonhuman subjects; be published a full-text paper in a peer-reviewed medical journal. Results: The studies considered eligible for this narrative review presented results in agreement with the difference in sex and orofacial pain. Patients were almost always adults, with particular focus on patients’ sex. Clinical conditions were predominantly TDM pain. Since sexual dimorphism was detected in TMD pain, the results are focused on women. Conclusion: The findings of this review suggest that there is difference in the occurrence and development of pain according to the individual’s sex, women being more susceptible to TMD pain.

Influence of ethanol and morphine on pain perception evoked by deep tissue injury

The aim of this study was to evaluate the effect of ethanol and morphine on nociceptive behavioral responses evoked by the injection of formalin into the temporomandibular joint region of rats (the TMJ formalin test). In experiment 1, animals were given an ethanol solution (6.5 por cento) or tap water to drink for 4 and 10 days, before the procedure for TMJ pain. In the group treated for 4 days, significant analgesia was observed in the TMJ formalin test, whereas the group treated for 10 days did not show this effect, revealing the development of tolerance to ethanol antinociceptive effects. In experiment 2, animals were submitted to chronic regimen of ethanol (6.5 por cento for 10 days did not show this effect, revealing the development of tolerance to ethanol antinociceptive effects...

Efeito da dexametasona e do meloxicam sobre o extravasamento plasmático induzido por carragenina na ATM de ratos / Effect of dexamethasone and meloxicam on plasma extravasation induced by carrageenan into rat temporomandibular joint

A dor orofacial comumente ocorre devido à inflamação aguda ou crônica. Porém, pouco se sabe sobre os mecanismos fisiopatológicos envolvidos na inflamação e na dor inflamatória presentes nas disfunções temporomandibulares. Nosso objetivo foi desenvolver um modelo para o estudo da inflamação aguda na região da articulação temporomandibular (ATM) de ratos utilizando carragenina (CA) e verificar os possíveis efeitos de drogas antiinflamatórias nesse modelo. A inflamação foi avaliada através do extravasamento plasmático (EP) do corante azul de Evans, por espectrofotometria comparada à ATM contralateral que serviu como controle e recebeu injeção de salina. Um experimento com relação ao tempo do efeito da CA sobre o EP do corante Azul de Evans revelou um efeito máximo no tempo de 60 min após a administração. O experimento dose resposta demonstrou que a administração de CA a partir da dose de 300 µ/50 µL, causava um EP estatisticamente significante em relação ao controle. A administração de drogas antiinflamatórias (dexametasona e meloxicam) somente foram capazes de reduzir a inflamação em altas doses. Concluímos que pico de EP induzido pela administração periarticular de CA ocorre em 60 minutos e que o EP induzido pela CA pode ser inibido pelos antiinflamatórios dexametasona e meloxicam

Os antiinflamatórios dexametasona, meloxicam e indometacina não inibem a inflamação nerogênica induzida pelo óleo de mostarda na atm dos ratos / Daxamethason, meloxicam and indomethacin do not inhibit the neurogenic inflammation imduced by the mustard oil in the tmj of rats

A inflamação neurogênica pode estar envolvida no desenvolvimento das desordens da articulaçao têmporo-mandibular (ATM). O óleo de mostarda (OM) tem sido muito utilizado para o estudo da inflamação neurogênica. Entretanto, na região da ATM, ainda não é totalmente conhecido o mecanismo inflamatório do OM. Investigar se, na ATM, o OM induz um processo inflamatório de caráter neurogênico e se as prostaglandinas participam dessa inflamação. Ratos machos (Wistar), anestesiados, receberam OM (0,25 por cento - grupo I; 0,5 por cento - grupo II e 2,5 por cento - grupo III) ou óleo mineral (grupo IV - controle) na ATM direta. Ratos adicionais foram tratados com win 51,708 (grupos V, VI e VII), meloxicam (grupo VIII), dexametasona(grupo IX), indometacina (grupo X), solução salina (grupos XI, XII, XIII e XIV - controles) e, na sequência, o OM (0,25 por cento) foi aplicado na ATM direita. A inflamaçaõ da ATM foi averiguada pelo extravasamento plasmático de proteínas (EP) ligadas ao corante azul de Evans. A aplicação do OM (0,25 por cento, 0,5 por cento e 2,5 por cento) na ATM induziu EP significativamente maior (p < 0,05 por cento) que o grupo controle. O win 51,708 reduziu significativamente (p < 0,05 por cento) EP induzido pelo OM a 0,25 por cento em relação ao grupo controle. Entretanto, os antiinflamatórios dexametasona, meloxican e indometacina foram ineficazes em inibir esse EP. A inflamação induzida pelo OM na ATM é decorrente de um mecanismo neurogênico e as prostaglandinas não são essenciais para o desenvolvimento do EP associado com esse modelo de inflamação

Atividade microbiana das plantas arnica, bardana e tanchagem / Antimicrobian activity plants Porophyllum ruderale, Arctium lappa and Plantago

Utilizando-se extratos hidroalcoólicos, obtidos por maceraçäo a frio a partir das folhas frescas das plantas medicinais Porophyllum ruderale, arnica; Artium lappa minor, bardana e Plantago mayor, tanchagem, foram realizados testes da atividade antimicrobiana destas em relaçäo a Staphylococcus aureus, Streptococcus pyogenes tipo A e Streptococcus pyogenes tipo B. Tais testes foram efetuados de acordo com o método de Kyrby-Bauer ou de difusäo em disco e pela técnica de diluiçäo em tubos. Os extratos das plantas em estudo, adicionados ao meio de cultura contaminado com os respectivos microorganismos, provocaram inibiçäo destes, demonstrando o efeito antimicrobiano das referidas plantas

Estudo da resistência de amostras de Staphylococcus aureus a diferentes antibióticos / A study of multiple antibiotic resistance in samples of Staphylococcus aureus

Um total de 88 amostras de Staphylococcus aureus, das quais 44 isoladas da narina e pele de estudantes e outras 44 isoladas do ambiente hospitalar, foi testado frente a 11 antibióticos. Os resultados obtidos mostraram níveis de resistência relativamente altos, principalmente com relaçäo à penicilina, nas amostras de estudantes