Effect of age, sex and gender on pain sensitivity: A narrative review

© 2017 Eltumi And Tashani. Introduction: An increasing body of literature on sex and gender differences in pain sensitivity has been accumulated in recent years. There is also evidence from epidemiological research that painful conditions are more prevalent in older people. The aim of this narrative review is to critically appraise the relevant literature investigating the presence of age and sex differences in clinical and experimental pain conditions. Methods: A scoping search of the literature identifying relevant peer reviewed articles was conducted on May 2016. Information and evidence from the key articles were narratively described and data was quantitatively synthesised to identify gaps of knowledge in the research literature concerning age and sex differences in pain responses. Results: This critical appraisal of the literature suggests that the results of the experimental and clinical studies regarding age and sex differences in pain contain some contradictions as far as age differences in pain are concerned. While data from the clinical studies are more consistent and seem to point towards the fact that chronic pain prevalence increases in the elderly findings from the experimental studies on the other hand were inconsistent, with pain threshold increasing with age in some studies and decreasing with age in others. Conclusion: There is a need for further research using the latest advanced quantitative sensory testing protocols to measure the function of small nerve fibres that are involved in nociception and pain sensitivity across the human life span. Implications: Findings from these studies should feed into and inform evidence emerging from other types of studies (e.g. brain imaging technique and psychometrics) suggesting that pain in the older humans may have unique characteristics that affect how old patients respond to intervention

Toxicological evaluation of long-term intravenous administration of amitraz in horses

With the aim of determining the possible toxicity of amitraz after its prolonged use in horses, six English Thoroughbred horses received intravenous injections of amitraz (0.05, 0.10 or 0.15 mg/kg) weekly for four months, constituting the experimental group. Eight other animals (control group), via the same route following the same drug administration schedule and period of time, received the vehicle, dimethylformamide. At the end of this period, blood was collected from all the animals, and a comparison was made of the means of the values obtained for the various blood analyses: complete hemogram, alkaline phosphatase, gamma-glutamyltransferase, blood urea nitrogen, lactate dehydrogenase, aspartate aminotransferase, creatine phosphokinase, glucose, albumin, total protein, creatinine, Na+ , K+, Cl- and CO2. The results for the biochemical characteristics showed that only the mean value for urea of the animals submitted to treatment with amitraz was significantly different than the mean value obtained for the control group. The analyses of the hematological characteristics showed that no significant differences between groups were observed. Similarly, the measurement of blood electrolyte levels demonstrated that long-term treatment with amitraz did not cause significant changes in the variables analyzed. The results indicate that amitraz, given in the doses employed in this study, did not show signs of inducing toxic effects in vital organs, even after prolonged administration

Toxicological evaluation of long-term intravenous administration of amitraz in horses

Estudou-se a possível toxicidade do uso prolongado do amitraz em eqüinos utilizando-se seis éguas Puro Sangue Inglês, as quais receberam injeções intravenosas de amitraz (0,05, 0,10 ou 0,15 mg/kg) semanalmente, durante quatro meses (grupo experimental). Outros oito animais (grupo-controle), seguindo o mesmo esquema de administração e período, receberam o veículo dimetilformamida. Ao final desse período colheram-se amostras de sangue dos animais e compararam-se as médias dos valores obtidos para as seguintes variáveis do sangue: hemograma completo, fosfatase alcalina, gama-glutamiltransferase, nitrogênio uréico, desidrogenase láctica, aspartato aminotransferase, creatina fosfoquinase, glucose, albumina, proteína total, creatinina, Na+ , K+, Cl- e CO2. Apenas as médias dos valores de nitrogênio uréico dos animais submetidos ao tratamento com amitraz foram diferentes das médias dos valores obtidos para o grupo-controle. As análises das características hematimétricas mostraram que não houve diferenças significativas quando se compararam os dois grupos. As dosagens de eletrólitos no sangue também demonstraram que o tratamento prolongado com amitraz não causou alterações significativas nas características analisadas. O amitraz na dosagem empregada não induziu efeitos tóxicos sobre órgãos vitais, mesmo após administração prolongada.With the aim of determining the possible toxicity of amitraz after its prolonged use in horses, six English Thoroughbred horses received intravenous injections of amitraz (0.05, 0.10 or 0.15 mg/kg) weekly for four months, constituting the experimental group. Eight other animals (control group), via the same route following the same drug administration schedule and period of time, received the vehicle, dimethylformamide. At the end of this period, blood was collected from all the animals, and a comparison was made of the means of the values obtained for the various blood analyses: complete hemogram, alkaline phosphatase, gamma-glutamyltransferase, blood urea nitrogen, lactate dehydrogenase, aspartate aminotransferase, creatine phosphokinase, glucose, albumin, total protein, creatinine, Na+ , K+, Cl- and CO2. The results for the biochemical characteristics showed that only the mean value for urea of the animals submitted to treatment with amitraz was significantly different than the mean value obtained for the control group. The analyses of the hematological characteristics showed that no significant differences between groups were observed. Similarly, the measurement of blood electrolyte levels demonstrated that long-term treatment with amitraz did not cause significant changes in the variables analyzed. The results indicate that amitraz, given in the doses employed in this study, did not show signs of inducing toxic effects in vital organs, even after prolonged administration.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Effect of amitraz and xylazine on some physiological variables of horses

Avaliaram-semos os efeitos das injeções intravenosas (iv) de amitraz (0,1mg/kg) e xilazina (1mg/kg), em cavalos, sobre a atividade cardíaca, freqüência respiratória, atividade motora intestinal, temperatura retal, sudorese e freqüência de apreensão de alimentos. O amitraz causouuma diminuição significativa da atividade cardíaca, da freqüência respiratória e da movimentação intestinal, mas esses efeitos não foram tão pronunciados quanto os causados pela xilazina. O amitraz causou, também, um relaxamento significativo da musculatura lisa retal, e um aparente aumento da sudorese e da freqüência de cavalos flagrados mastigando feno. A temperatura retal não foi influenciada pelo amitraz. Os resultados indicam que o amitraz, na dose utilizada, não causou efeitos colaterais severos em cavalos.The effect of the intravenous injection of amitraz (0.1mg/kg) to horses on cardiac activity, respiratory rate, intestinal motor activity, rectal temperature, sweating and masticating was evaluated and compared to the effect of intravenous administration of xylazine (1mg/kg, iv) on heart rate, respiratory rate and intestinal activity. Amitraz caused a significant decrease in heart activity, respiratory rate and intestinal movements, but these effects were not as pronounced as those caused by xylazine. Amitraz also caused a significant relaxation of the rectal smooth muscle, and an apparent increase in sweating and in the frequency of horses found masticating hay. Rectal temperature was not influenced by amitraz. The results indicated that amitraz, at the dose used, did not cause severe side effects in horses.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq