Nos últimos 50 anos, a hipotermia tem demonstrado ser um excelente agente neuroprotetor nas lesões isquêmicas encefálicas. A hipotermia moderada (31(0) C - 33(0) C) provou também apresentar as mesmas propriedades protetoras, sem os efeitos deletérios da hipotermia profunda. Dentre alguns mecanismos de lesão que são melhorados pela hipotermia e piorados pela hipertermia moderada, podemos citar a diminuição da demanda de oxigênio pelo encéfalo e a redução da glicina e aminoácidos excitatórios, evitando a produção de radicais de oxigênio, com aumento da peroxidase e conseqüente lesão aos lípides, proteínas e DNA, assim como pela ativação microglial e despolarização isquêmica. Alguns estudos demonstraram que a inflamação potencializa a lesão isquêmica e que a hipotermia pode reduzir a infiltração leucocitária nas áreas isquêmicas. Para melhor elucidar os mecanismos pelos quais a hipotermia apresenta efeito neuroprotetor através da redução da inflamação, no processo isquêmico, escolhemos o método utilizando a indução de uma reação inflamatória com a utilização de uma substância com capacidade promover intensa reação inflamatória em encéfalos de ratos. Dois grupos de dez animais foram submetidos a um mesmo procedimento cirúrgico: a calota craniana foi parcialmente removida, a duramáter aberta e uma substância com potente efeito inflamatório (carragenina a 5%) foi gotejada. A pele foi suturada e, para o grupo com neuroproteção, uma bolsa de gelo foi colocada, cobrindo toda a superfície craniana, de modo a manter a temperatura encefálica entre 29,5(0) C e 31(0) C durante 120 minutos. Três dias após, os animais foram sacrificados e os encéfalos examinados. O grupo protegido pela hipotermia apresentou considerável redução na infiltração leucocitária, demonstrando que a hipotermia pode apresentar função neuroprotetora por meio de uma redução no processo inflamatório.

Over the last 50 years deep hypothermia (23(0) C) has demonstrated to be an excellent neuroprotective agent in cerebral ischemic injury. Mild hypothermia (31-33(0) C) has proven to have the same neuroprotective properties without the detrimental effects of deep hypothermia. Mechanisms of injury that are exaggerated by moderate hyperthermia and ameliorated by hypothermia include, reduction of oxygen radical production, with peroxidase damage to lipids, proteins and DNA, microglial activation and ischemic depolarization, decrease in cerebral metabolic demand for oxygen and reduction of glycerin and excitatory amino acid (EAA) release. Studies have demonstrated that inflammation potentiates cerebral ischemic injury and that hypothermia can reduce neutrophil infiltration in ischemic regions. To further elucidate the mechanisms by which mild hypothermia produces neuroprotection in ischemia by attenuating the inflammatory response, we provoked inflammatory reaction, in brains of rats, dropping a substance that provokes a heavy inflammatory reaction. Two groups of ten animals underwent the same surgical procedure: the skull bone was partially removed, the duramater was opened and an inflammatory substance (5% carrageenin) was topically dropped. The scalp was sutured and, for the group that underwent neuroprotection, an ice bag was placed covering the entire skull surface, in order to maintain the brain temperature between 29,5-31(0) C during 120 minutes. After three days the animals were sacrificed and their brains were examined. The group protected by hypothermia demonstrated a remarkable reduction of polymorphonuclear leukocytes (PMNL) infiltration, indicating that mild hypothermia can have neuroprotective effects by reducing the inflammatory reaction.

The ethanolic extract (EE) of Acosmium subelegans (Mohlenbr) Yakovl (perobinha-do-campo) was tested to behavioral paradigms in mice to investigate its putative central depressant effect. Oral pretreatment with the EE significantly reduced in a dose-dependent way the locomotor activity and increased by 30-55% the barbiturate sleep duration relatively to control values. At the highest dose (1,0 g.kg-1) it decreased the extension time/flexion time ratio of the maximal electroshockinduced convulsions, enhanced the latency to the pentylenetetrazol-induced convulsions and diminished by 26% the number of seizures, indicating an anticonvulsant action. No changes were observed in the motor coordination, the core temperature, climbing behavior, catalepsy and the plus-maze performance. The preliminary results indicate that the EE of A. subelegans induce a CNS depressant effect, more specifically an anticonvulsant effect that deserve a thorough investigation.

The pharmacological activities of a water extract (WE) of Ageratum conyzoides L, a plant populary known for its analgesic and anti-inflamatory properties, were studied in vivo and in vitro preparations. Oral administration (p.o.) of the water extract (WE, 0.1 to 5 g/Kg) to rats and mice induced quietness and reduced the spontaneous motility. the sleeping time induced by sodium pentobarbital (50 mg/Kg, i.p.) in mice was not altered by previous treatment with We (2 g/Kg, p.o.). The same treatment did not influence the paw edema induced by carrageenan or dextran, nor did it reduce the chronic paw edema induced by complete Freund's adjuvant or formaldehyde in rats. The tail flick response in immersion test and writhings induced by 0.8%acetic acid in mice were not altered by WE either. In isolated guinea-pig ilea WE (0.4 to 4 mg/ml) did not alter the EC50 values of histamine or acetylcholine, but reduced the maximal response to the agonists by 20 to 50%. We (0.01 to 10 mg/ml) produced tonic contractions of the ileal smooth muscle proportional to the doses, reaching a maximum of 75% relatively to the maximum obtained with histamine. Those contractions were blocked by diphenhydramine (10 nM) and reduced by 32% in presence of atropine (10 nM). The results indicated that oral treatment of rodents with A. conyzoides L neither reduced the inflammatory edema nor did it decrease the reaction to pain stimuli. In vitro the extract presented an unexpected histamine-like activity characteristic of a partial agonist. The results did not confirm the popular medicinal indications of the plant.

Baccharus triptera Mart, is a widespread Compositae used in Brazilian folk medicine to treat gastrointestinal disturbances, rheumatic disease, mild fever, diabetes and as an anti-helminthic. Water extract of small branches of the plant (WE) administered to mice and rats (0.1 to 2 g/Kg, p.o) did not alter spontaneous motor activity, sleeping time induced by barbiturates or the tailflick response in mice. The extract decreased by 40 por cento the number of writhings induced by 0.8 por cento scetic acid, i.p., but did not influence paw edema induced by carrageenan or dextran in rats WE (2g/Kg, p.o.) decreased the intestinal transit of charcoal in mice by 20//. Gastric secretion in pylorus ligated rats was reduced after treatment with WE (1 and 2 g/Kg. i.p. or intraduodenal and the gastric pH was raised. The extract (1 g/Kg, p.o.) prevented gastric ulcers induced in rats by immobilization at 4ºC, but not those induced by indomethacin (10 mg/Kg, s.c.). The results indicate that WE may relieve gastrointestinal disorders by reducing acid secretion and gastrointestinal hiperactivity. Neither analgesic nor anti-inflammatory activities were detectable.

Analgesic and anti-inflammatory activities of water (WE) and ethanolic (EE) extracts of Scoparia dulcis L. were investigated in rats and mice, and compared to the effects induced by Glutinol, a triterpene isolated by purification of EE. Oral adminsitration (p.o.) of either WE or EE (up to 2 g/Kg) did not alter the normal spontaneous activity of mice and rats. The sleeping time induced by sodium pentobarbital (50 mg/Kg, i.p.) was prolonged by 2 fold in mice pretreated with 0.5 g/Kg EE, p.o. Neither extract altered the tail flick response of mice in immersion test, but previous administration of EE (0.5 g/Kg, p.o.) reduced writhings induced by 0.8% acetic acid (0.1 ml/10 g, i.p.) in mice by 47% EE (0.5 and 1 g/Kg, p.o.) inhibited the paw edema induced by carrageenan in rats by respectively 46% and 58% after 2 h, being ineffective on the paw edema induced by dextran. No significant analgesic or anti-edema effects were detected in animals pretreated with WE (1 g/Kg, p.o.). Administration of Glutinol (30 mg/Kg, p.o.) reduced writhing induced by acetic acid in mice by 40% and the carrageenan induced paw edema in rats by 73%. The results indicate that the analgesic activity of S dulcis L. may be explained by explained by an anti-inflammatory activity probably related to the triterpene Glutinol.

O Cannarus fulvus Planch é utilizado em Goiás por ser "bom para o coração". Este trabalho estudou, a atividade farmacológica do extrato bruto etanólico (EE) do pó da casca do caule e da fração hidrossolúvel (FH) obtida após partição benzina/água. O EE e a FH produziram em ratos e camundongos diminuição da motilidade, sonolência sem hipnose, dificuldade respiratória, analgésia e arrastamento do trem posterior; estes proporcionais às doses. As DL50 em camundongos foram 210+/-22 e 310+/-52mg/kg, i.p. para o EE e FH respectivamente. A FH prolongou o sono barbitúrico, o tempo de reação ao calor na placa, quente e antagonizou (80%) as ações convulsivantes do pentilenotetrazol, mas não as da estricnina. Protegeu (100%) camundongos contra a ação letal do pancurônio e potencializou a ação da succinilcolina. Em preparações isolada, a FH potencializou (20%) a contração do diafragma em resposta ao estímulo elétrico do nervo frênico de ratos e reverteu o bloqueio neuromuscular produzido pela d-tubocurarina, em átrios de ratos e cobaias a freqüência e a força de contração não foram alteradas. As injeções do EE e FH em ratos anestesiados produziram hipotensão (5 a 100mg/kg); doses maiores foram letais. Os dados obtidos não confirmaram ação cardiativa direta. A planta apresentou ações depressões do S.N.C., analgésica, anticonvulsivante e descurarizante.

Connarus fulvus Planch is populary utilized in the State of Goiás because it is said to be "good for the heart". This paper studied the pharmacological activities of the crude ethanolic extract (EE) of the powdered bark and of the hirosoluble fraction (HF) of the benzine/water partition. The EE and HF produced in rats andmices a decrease in locomotion, certain drowsiness, respiratory problems, insensitivity to pain and weakness of the posterior limbs. These effects were proportional to the administered doses. The DL50 in mice were 210+/-22 and 310+/-52mg/kg, i.p. for the EE and HF, respectively. The HF potenciated barbiturate - induced sleeping-time, reaction time to heat in the hot-plate and, in 80% of the cases, it antagonized the convulsive actions of PENTYLENETETRAZOL but not of STRYCHNINE. It protected the mice, in all of the cases, against the lethal action of PANCURONIUM and potenciated the action of SUCCINYLCHOLINE. in isolated tissues the HF potenciated, in 20% of the cases, contrations of the diaphragm in response to electrical stimulus of the phrenic nerve of the rats and reversed the neuromuscular blonde produced by d-TUBOCURARINE. In rat and guinea pig atriums electrically stimulated neither the chronotropism nor inotropism were altered. The injection of EE nor HF in rats under anesthetics produced hypotension (5 to mg/kg) while higher doses were lethal. The data obtained from studies didn't confirm direct action on the heart. The plant thus presented depressive action in the CNS, analgesic and anticonvulsive action while, it also annuled the effect of CURARE.