Pain threshold variations in female rats as a function of the estrus Cycle

In this study, the response of female rats in different phases of the estrus cycle to nociceptive stimulation was evaluated using thermal (hot plate and tail immersion) and chemical (formalin) tests. In the hot plate test, the paw licking latency fell significantly (p < 0.05) in the metestrus and diestrus phases compared with the proestrus and estrus phases. The observations in the tail immersion test also followed the same pattern. The significant reductions in the paw licking and tail withdrawal latencies due to a lowered threshold denote an increase in pain sensitivity in the metestrus and diestrus phases. In the formalin test, the licking time fell significantly from the metestrus to the diestrus phase compared with the proestrus and estrus phases, the reduction in this test which was due to an increased threshold connotes a decrease in pain sensitivity. The results therefore seem test dependent. In conclusion, pain threshold in female rats depends on the estrus state. Keywords:Pain threshold, Variation, Estrus cycle Nig. J. Physiol. Sci. 26 (June 2011) 067 – 07

Chronic vitamin C administration induces thermal hyperalgesia in male rats

Against a backdrop of neurological effects, the effects of acute and chronic administration of vitamin C (600mg/kg) on pain processing were investigated in male rats. Chronic administration of vitamin C induced significant thermal hyperalgesia while acute administration had no effect. In addition, the intraperitoneal administration of vitamin C produced observable abdominal writtings similar to what has been observed with acetic acid. We conclude that chronic vitamin C exerts facilitatory central nervous system effects and a possibility of using intraperitoneal injection of vitamin C as an animal model of pain is suggested. Keywords: vitamin C, pain, hyperalgesia, nociception, ascorbic acidNigerian Journal of Health and Biomedical Sciences Vol. 4(2) 2005: 153-15

Dysphania ambrosioides (L.) Mosyakin & Clemants

Dysphania ambrosioides (L.) Mosyakin & Clemants (= Chenopodium ambrosioides L.) is an American aromatic species used as medicinal and culinary purposes since pre-Columbian times by Aztecs and Mayans in Mesoamerica (where is called epazote) and Andean communities and many others in South America (where is better known as paico). Currently, it is globally known by a wide diversity of cultures around the world, due to its cultivation and naturalization. Its uses are currently widespread in pluricultural contexts, by means the commercial circuits and mass media, especially the Internet. The main active constituents are essential oils, to which owes its aroma and flavor. It is toxic in high doses, but safe if is consumed in appropriated concentrations. The most widespread folk therapeutic use is as antiparasitic (anthelmintic, antimicrobial), and it is also employed against gastrointestinal disorders, as hypotensive, antipyretic, vulnerary, analgesic, anti-inflammatory, antitumor, sedative and anxiolytic, among others, many of which have been evaluated scientifically. The researches on its anticancer activity are very promising.Fil: Hurrell, Julio Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Etnobotánica y Botánica Aplicada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin