Evidence indicates that repeated exposure to stressful events sensitizes the motor and addictive effects of drugs of abuse in rats. Regarding a single exposure to one restraint stress, previous findings have shown that it is sufficient to induce behavioral sensitization to stimulating and reinforcing properties of abuse drugs (e.g., amphetamine and morphine), as measured by locomotor activity and conditioned place preference, respectively. It is well known that enhanced dopaminergic neurotransmission in the nucleus accumbens and striatum plays a critical role in the development and/or expression of repeated stress‐induced or drug‐induced sensitization. In addition, involvement of NMDA receptors has been implicated in its development. However, whether sensitization induced by a single restraint stress exposure represents the same neurobiologic phenomenon is unknown. We studied the following issues: (a) influence of a single restraint exposure on the stimulating effects of amphetamine on dopamine release by microdialysis from striatum and (b) involvement of glutamatergic pathways, specifically those innervating striatum, on stress‐induced sensitization to amphetamine, by administering MK‐801 ip (0.1 mg/kg) or intrastriatally (1 μg/0.5 μL) previous to an acute restraint stress. For microdialysis studies (a) or intrastriatal administration of MK‐801 (b), Wistar rats (250‐330 g) were implanted stereotactically under anesthesia with a guide cannula in the striatum. After 2 days, animals were immobilized for 2 hours in a Plexiglas device. Control animals remained in their home cages. The following day we evaluated the stimulating effect of amphetamine on (a) dopamine release from striatum or (b) locomotor activity. In studies (a), dialysis probes were inserted into the guide cannula, and baseline dopamine levels were collected for 2 hours before a challenge of amphetamine (1.5 mg/kg ip). Dialysates were then collected by 3 hours. Amphetamine challenge induced a significantly higher increase in dopamine release and locomotor activity in animals previously subjected to one restraint stress exposure, relative to that observed in the no‐restraint stress group. MK‐801 administered ip or intrastriatally blocked the restraint stress‐induced sensitization to amphetamine. First, our results point out that a single restraint stress exposure is a pertinent stimulus to induce sensitization of amphetamine's stimulating effects on dopaminergic neurotransmission in the striatum. Secondly, NMDA‐glutamatergic receptors, specifically those placed in the striatum, are implicated in the development of stress restraint‐induced sensitization.
Two hundred fifty samples of patients admitted to the Emergency Department at the Hospital Municipal de Urgencias, Córdoba, Argentina for a drug screening by HPTLC, FPIA, spectrophotometric methods, and HPLC/DAD were randomly selected. The rate of positive screens was 34.0% with the following rate distribution: 12.0% alcohol, 13.6% nonsteroid antiinflammatory drugs (NSAIDs), 2.0% anticonvulsants, 0.8% barbiturates, 0.4% narcotics, 0.4% antidepressants, 2.8% cocaine, and 2.0% cannabinoids. Psychoactive drugs (alcohol, cocaine, and cannabinoids) were detected in 43.9% of the patients admitted for traffic accidents, namely 35.71% alcohol, 2.38% alcohol-cocaine, 2.38% alcohol-cannabinoids, 2.38% cocaine-cannabinoids, and 2.38% alcohol-cocaine-cannabinoids. These results help identify the trend of use and/or abuse of drugs and its relationship with different causes of admission (accidents, overdose, and other pathologies), age, and gender.
Aim: To determine the magnitude of forces exerted by the different instruments on the dentine surface as well as the effect of the anatomical features of the canal and the experience of the operator. Method: A specific sensors mechanism connecting the removed tooth to a computerized system was used, which received the forces produced by the instrument when it was activated. Vestibular roots from maxillary first molars and mesial roots from mandibular first molars were used in the experiment. The roots were distributed in groups according to the age of the tooth as follows: group I 20/30 years; group II 40/50 years and group III > 60 years. The instruments used were conventional stainless steel files, flexible files, and a mechanized system. Filing and rotary movements were applied (positive and negative compression and rotation). The intervening operators were professionals with and without clinical experience. The analysis of the recorded graphs showed that the pressure exerted by hand instruments increased with age, both in the positive and in the negative pressures while those generated by the mechanized system were constant and very similar in the three age groups. However, there was a significant increase in pressure with rotary motion. Conclusion: The forces generated by manual instrumentation are very irregular and increase with age, not only due to dentin hardness but also as a result of anatomical factors. The forces of mechanized origin, on the contrary, are more regular and superior to those produced manually, especially the positive pressures caused by rotary motion. Lack of confidence and of experience observed in some dental practitioners highlights the need for preclinical training.KEY WORDS: dentin hardness, instrumentation, generation of forces, age. ResumenEl objetivo del presente trabajo fue determinar la magnitud de las fuerzas producidas por distintos instrumentos de uso endodóntico sobre la superficie dentinaria, como así también, la influencia que en ello tienen la anatomía del conducto y la experiencia del operador. Se empleó un mecanismo de sensores específicos que conectaba la pieza dentaria extraída a un sistema computarizado que receptaba las fuerzas que el instrumento producía cuando era accionado. En la experiencia se utilizaron raíces vestibulares de primeros molares superiores y mesiales de primeros molares inferiores, distribuidos en los siguientes tres grupos según la edad de las piezas: Grupo I de 20/30 años, Grupo II de 40/50 años y Grupo III mayores de 60 años. Los instrumentos utilizados fueron limas convencionales de acero inoxidable, limas flexibles y un sistema mecanizado (fuerzas continuas). Se aplicaron movimientos de limado y rotación (compresión y rotación positiva y negativa). Los operadores actuantes fueron profesionales con y sin experiencia clínica. El análisis de los gráficos registrados, permitió comprobar que la presión producida por los instrumentos manuales mostraba un evidente incremento con la edad, tanto en las positivas como negativas, mientras que las gen...
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