Hormonal and neural responses to restraint stress in an animal model of perimenopause in female rats.

The present study investigated the hormonal and neural responses to stress in a perimenopause animal model induced by 4-vinylcyclohexene diepoxide (VCD), which induces progressive follicular depletion in rodents, allowing studies on the transition to ovarian failure. Female rats, aged 28 days old, were s.c. injected for 15 consecutive days with corn oil or VCD. At 85 ± 5 days after the onset of treatment, the jugular vein was cannulated in the afternoon of metoestrus and in next morning (dioestrus) at 10.00 am, rats were subjected to 30 minutes of restraint stress. Blood samples were withdrawn before (-5 minutes), during (2, 5, 15 and 30 minutes) and after (45, 60 and 90 minutes) stress and plasma prolactin, progesterone and corticosterone levels were measured. Animals were perfused, brains processed for c-Fos/tyrosine hydroxylase (TH) in the locus coeruleus (LC) and c-Fos/corticotrophin-releasing factor (CRF) in the paraventricular nucleus (PVN). In unstressed rats the density of ß-endorphin fibres was assessed in LC and PVN. In VCD-treated rats, stress-induced prolactin peak was higher, basal and peak progesterone levels were lower, and both levels of corticosterone were similar to controls. However, the recovery period was longer for both adrenal hormones. In VCD-treated rats the number of c-Fos/TH and c-Fos/CRF-immunoreactive neurones was higher whereas the density of ß-endorphin fibres was lower in LC and PVN. We surmise that the hyperactivity of the LC and PVN neurones in VCD-treated rats may be a result of the lower progesterone levels that resulted in the decrease of ß-endorphin content in both nuclei, thus impairing the negative-feedback mechanism in the recovery period.

Non-pharmacological interventions during childbirth for pain relief, anxiety, and neuroendocrine stress parameters: A randomized controlled trial.

AIM: This study aimed to investigate the effect of warm shower hydrotherapy and perineal exercises with a ball on pain, anxiety, and neuroendocrine stress parameters during childbirth. METHODS: This randomized controlled trial was conducted with 128 women during childbirth, admitted for hospital birth in São Paulo, Brazil, from June 2013 to February 2014. The participants were randomly assigned into one of the following intervention groups: received warm shower hydrotherapy (GA); performed perineal exercises with a ball (GB); and combined intervention group, which received warm shower hydrotherapy and perineal exercises with a ball (GC) (n = 39). Pre-and post-intervention parameters were evaluated using visual analogue scales for pain and anxiety, and salivary samples were collected for the stress hormones analysis. RESULTS: Pain, anxiety, and epinephrine release decreased in the group performing perineal exercises with a ball (GB). ß-endorphin levels increased in this group (GB) after the intervention and showed significant difference in capacity to cause this effect (P = .007). However, no significant differences were observed in cortisol, epinephrine, and norepinephrine levels. CONCLUSIONS: Warm showers and perineal exercises could be considered as adjunct therapy for women suffering from pain, anxiety, and stress during childbirth. Clinical Trial Registry RBR-84xprt.

Uso do exercício resistido antagonizado por naloxone como fator de analgesia em sinovite aguda de joelho de ratos Wistar / Use of resistance exercise as a factor antagonized by naloxone of analgesia in acute knee synovitis in Wistar rats

A analgesia advinda do exercício físico pode ocorrer via liberação de opioides endógenos, no sistema nervoso central e na periferia. Contudo, a literatura ainda é controversa sobre vias e ações do exercício na dor. Assim, o objetivo da pesquisa foi avaliar se o exercício resistido produz alterações sobre o quadro nociceptivo e se sofre interferências pela aplicação de um inibidor de opioides. Foram utilizados 18 ratos, divididos em três grupos: G1 - hiperalgesia no joelho direito e não tratados; G2 - hiperalgesia e tratados com saltos em meio aquático; G3 - hiperalgesia, com prévia injeção de naloxone e posterior saltos. Para produzir a hiperalgesia, foi injetado no espaço articular tibiofemoral 100µl de formalina 5%. Para avaliação da dor foi utilizado o filamento de Von Frey digital na face medial da articulação tibiofemoral direita. Os momentos de avaliação foram: pré-lesão (AV1), após 15 (AV2) e 30 (AV3) minutos e uma hora (AV4). O exercício foi saltos em meio aquático e ocorreu após AV2. Com sobrecarga de 50% do peso, o animal realizou quatro séries de cinco saltos, com intervalo de três minutos. Para G1, houve aumento nociceptivo, com redução significativa e volta dos valores iniciais em AV4; G2 mostrou, após o exercício físico, restauração do limiar, com retorno aos valores basais; para G3, houve diminuição do limiar, sem restauração ou aumento significativo do mesmo. Conclui-se que houve analgesia com uso do exercício físico e que a mesma foi alterada por bloqueador de betaendorfina.

Analgesia arising from exercising can occur via release of endogenous opioids in the central nervous system and periphery. However, the literature remains controversial about exercise ways and actions in pain. Thus, the aim of this study was to evaluate whether resistance exercise produces changes on the nociception and suffers interference by applying an opioid inhibitor. 18 rats divided into three groups were used: G1 - hyperalgesia on right knee and untreated; G2 - hyperalgesia and treated with jumps in water; G3 - hyperalgesia with previous injection of naloxone and subsequent jumps. To produce hyperalgesia,100 ul of 5% formalin was injected in the tibiofemoral joint space. Pain was assessed using a digital von Frey filament on the right medial tibiofemoral joint. The evaluation periods were: pre-injury (EV1) after 15 minutes (EV2) and 30 minutes (EV3) and one hour (EV4). The applied exercise was jumping in water and it occurred after EV2. The animal performed 4 sets of 5 jumps, with an interval of 3 minutes and overload of 50% of body weight. In G1, nociceptive increase was observed, with significant decrease and return to initial baseline values in AV4; G2 showed threshold restoration after exercise and return to baseline; G3 reduced thresholds, without restoration or significant increase in them. We concluded that there was analgesia with use of exercise and that it was altered by blocking beta-endorphin.