Jorge Miño

Memory facilitation with posttrial injection of oxotremorine and physostigmine in mice.

The immediate posttrial injection of oxotremorine (0.125, 0.250 and 0.500 μMol/kg i.p.) and equimolecular doses of physostigmine can facilitate the retention of a passive avoidance response in mice. Injections given 10 min after training also significantly facilitate retention, but injections given 30 or 120 min after training do not affect retention. These findings suggest an action of oxotremorine and physostigmine on mechanisms involved in memory storage. The enhanced retention produced by oxotremorine and physostigmine was blocked by pretreatment with atropine (2 μMol/kg, 20 min, i.p.) but was not affected by methylatropine (2 μMol/kg, 20min, i.p.). The retention was not modified by posttrial injection of metoxotremorine (0.250 μMol/kg i.p.) or neostigmine (0.250 μMol/kg i.p., quaternary analogs of oxotremorine and physostigmine, respectively. The results suggest a central action of both cholinergic agents attributable to an activation of muscarinic brain receptors.

Pulsed Electromagnetic Fields in Experimental Cutaneous Wound Healing in Rats

Electromagnetic fields are now being used in many diseases such as osseous, ligamental, cartilaginous, or nervous reparation, diabetes, and myocardial or cerebral ischemia. Although many publications show the usefulness of magneto-therapy, discrepancies exist about the utility of electromagnetic fields in skin wound healing. The objective of this work was to study the effect of pulsed electromagnetic fields on wound healing in rats. Twenty-two male Wistar rats were used; a circular lesion was made in the back of each animal. They were divided into three groups: group C (control) with sham treatment (n = 8), group NF, treated with topical nitrofurazone solution (n = 7), and group PEMF, treated with pulsed electromagnetic fields of 20 mT (n = 7). The treatments were 35 minutes twice a day. The absolute and relative values of the area and perimeter of the wounds showed significantly lower values in the PEMF group at days 7, 14, and 21 compared with those in group C (p < 0.01, analysis of variance), whereas the PEMF group showed significantly lower values at day 21 only compared with the NF group (p < 0.01, analysis of variance). The results suggest a significant beneficial stimulation in the wound healing process in rats treated with PEMF, which could lead to the development of a practical tool for research and clinical use.

Evaluation of antinociceptive, antinflammatory activities and phytochemical analysis of aerial parts of Urtica urens L.

The antinociceptive and antiinflammatory activities of the ethanol extract of the aerial part of Urtica urens were determined by experimental animal models. U. urens extract was found to possess significant antinociceptive activity in chemically induced mouse pain models (ED50 39.3 mg/kg: 17.2–74.5 mg/kg) in the writhing test and 62.8% inhibition of the licking time in the late phase of the formalin test at a dose of 500 mg/kg p.o. and antiinflammatory activity on carrageenan‐induced rat hind paw edema (41.5% inhibition at a dose of 300 mg/kg i.p.). The extract displayed activity neither in the thermal model of pain nor in the topical inflammation model. The major component of the extract was determined as chlorogenic acid (670 mg/1000 g dry weight) and could be partly responsible for this activity. Copyright

The hypoglycemic effect of Phyllanthus sellowianus fractions in streptozotocin-induced diabetic mice

Phyllanthus sellowianus Müller Arg. (Euphorbiaceae) is a plant used in folk medicine as a hypoglycemic and diuretic agent. The present study describes the hypoglycemic effect of fractions obtained from the stem barks of P. sellowianus using a bioassay-guided fractionation protocol and streptozotocin-induced hyperglycemic mice. The aqueous extract was partitioned between dichloromethane and butanol to yield the dichloromethane (D), butanol (B) and the remaining aqueous (A) fractions. Fractions B and A, administered at the dose of 200 mg/kg p.o., caused a significant reduction in blood glucose concentration at 6 and 9 h, while the same dose of fraction D was ineffective. The reduction in blood glucose levels obtained with the B and A fractions was similar to that observed with glibenclamide (10 mg/kg) which was used as a reference for the hypoglycemic activity. Phytochemical analysis of fractions B and A revealed the presence of flavonoid compounds, of which rutin and isoquercitrin were the major constituents, respectively. The possible involvement of these flavonoids in the hypoglycemic effect of the active fractions is discussed.

Antinociceptive effect of some Argentine medicinal species of Eupatorium.

Eupatorium laevigatum, E. arnottianum and E. subhastatum, plants used in Argentine folk medicine for the treatment of inflammation and pain related problems, were evaluated for analgesic activity. The infusions of these species (500 mg/kg, p.o.) produced a reduction in the number of stretches of 46.6%, 41.5% and 35.6% respectively, in the acetic acid induced writhing test. This antinociceptive effect of the infusions was not reversed by pretreatment with naloxone. The infusions studied did not produce antinociceptive effects when assayed in the hot plate test. These results suggest that the analgesic activity is exerted by a mechanism unrelated to interaction with opioid systems.

Antinociceptive effect of the aqueous extract of Balbisia calycina

The aqueous extract from the aerial parts of Balbisia calycina (Gris.) A.T. Hunziker et Ariza (Ledocarpaceae), was evaluated for antinociceptive activity using the abdominal constriction, hot plate and formalin tests. The extract was administered orally to male mice at doses of 200, 400 and 800 mg/kg. A dose-dependent antinociceptive effect of the extract was obtained with the abdominal constriction test at doses of 400 and 800 mg/kg. This antinociceptive effect was not reversed by pretreatment with naloxone. No significant response was obtained with the hot plate test. With the formalin test doses of 400 and 800 mg/kg had no significant effect during the first phase of the test (0-5 min), while with the dose of 800 mg/kg, a significant inhibition during the second phase (15-30 min) was observed. The phytochemical investigation of the aqueous extract of B. calycina revealed the presence of the flavonoids luteolin, avicularin and hyperoside. The possible involvement of these flavonoids (specially luteolin) in the antinociceptive action is discussed.

Diuretic activity of an aqueous extract of Phyllanthus sellowianus.

Phyllanthus sellowianus Muell. Arg. (Euphorbiaceae) is used widely as a hypoglycemic and diuretic agent in South American folk medicine. In order to assess the diuretic activity of this plant, test animals were treated with a single oral administration of an aqueous extract (5% w/v) of the stem bark of P. sellowianus (400 mg/kg body weight), which produced after 8 h a significant increase in the urinary excretion. In the studies on acute toxicity in mice neither mortality nor neurobehavioral or autonomic profile changes could be observed.

Antidiabetic activity of Phyllanthus sellowianus in streptozotocin-induced diabetic rats.

The aqueous extract (5% w/v) of the stem barks of Phyllanthus sellowianus Müller Arg. (Euphorbiaceae) was administered orally at the dose of 4 ml/100 g body weight (corresponding to 2 g of dry plant material/kg body weight) to normal and streptozotocin-induced diabetic rats. Blood glucose was estimated 3 weeks after daily administration of the extract and was compared to the pre-treatment level. The results show that the administration of the extract significantly lowered the blood glucose in the diabetic rats.

Psychopharmacological effects of Artemisia copa aqueous extract in mice

Objective: To evaluate the aqueous extract from aerial parts of Artemisia copa Phil. (Asteraceae) administered orallyfor its psychopharmacological activities in several experimental models Methods: The extract was administered p.o. in Swiss albino mice and tested on pentobarbital-induced hypnosis, locomotor activity, exploration in the hole-board, anxiolytic like profile evaluated in the marble-burying test and anticonvulsant activity on convulsions induced by pentylenetetrazol. Results: Artemisia copa at doses up to 1.5 g/kg produced a dose-dependent sleep induction and potentiation of sub-hypnotic and hypnotic doses of pentobarbital. The extract also produced a dose-dependent increase and decrease in the spontaneous motor activity (0.5–1.5 g/kg, respectively), no disruption or a decrease on exploratory (hole-board) behavioral profiles (0.5–1.5 g/kg respectively) and a dose-related anxiolytic-like activity as indicated by increases in the percentage of marbles they left uncovered in the marble-burying test at doses (0.5 g/kg) that do not disrupt the motor activity. In addition, the extract (1.5 g/kg) produced a significant increase in the latency time and a decrease in the duration of seizures and mortality induced by PTZ 75 mg/kg in mice. Conclusion: These results suggest that the aqueous extract of Artemisia copa may contain sedative principles with potential anxiolytic and anticonvulsant activities.

COMPENSACIÓN: UN NUEVO CONCEPTO RELACIONADO CON LA LATERALIDAD CEREBRAL. SU APLICACIÓN A REGIONES DEL LÓBULO FRONTAL, INCLUIDA EL ÁREA MOTORA DEL LENGUAJE (DE BROCA)

: Cuando se determina la asimetria de una estructura bilateral formada por subregiones asimetricas con lateralidades opuestas, queda enmascarada (compensada), total o parcialmente, la existencia de las diferencias interhemisfericas de tales subregiones. Para cuantificar esta realidad, hemos establecido un nuevo parametro: la compensacion. El objetivo del presente trabajo, realizado en cerebros humanos postmortem, esta dirigido a determinar los porcentajes de compensacion, de asimetria de peso y de superficie cortical, de tres regiones cerebrales pertenecientes al lobulo frontal: 1. El area de motora del lenguaje (de Broca). 2. La porcion anterior del giro frontal inferior. 3. El giro frontal inferior en su totalidad. Para valores de peso y de superficie cortical para el area motora del lenguaje los porcentajes de casos con compensacion parcial o total son, respectivamente, 50 y 42%; para la porcion anterior del giro frontal inferior 70 y 67%; y para el giro frontal inferior en su totalidad 96 y 96%. En este ultimo el porcentaje de casos con compensacion es significativamente mayor que en las otras dos regiones (Chi2). Similares valores porcentuales de asimetria pueden darse en casos con muy diferentes valores porcentuales de compensacion. Esto demuestra que con el solo calculo de la asimetria se enmascaran aspectos de las diferencias interhemisfericas. De ahi que ambos valores son complementarios