Handling of adolescent rats improves learning and memory and decreases anxiety.

Some environmental interventions can result in physiologic and behavioral changes in laboratory animals. In this context, the handling of adolescent or adult rodents has been reported to influence exploratory behavior and emotionality. Here we examined the effects of handling on memory and anxiety levels of adolescent rats. Male Sprague-Dawley rats (age, 60 d) were divided into a control group and a handled group, which were handled for 5 min daily, 5 d per week, for 6 wk. During handling bouts, the rat was removed from its cage, placed in the experimenter's lap or on the top of a table, and had its neck and back gently stroked by the experimenter's fingers. During week 6, each rat's anxiety level was evaluated in the elevated plus-maze (EPM) test. Learning and memory were evaluated 48 h later, by measuring escape latency in the elevated plus-maze test. Plasma corticosterone and catecholamine levels were measured also. Norepinephrine levels were lower in the handled rats compared with control animals, with no differences in epinephrine and corticosterone. As compared with the control rats, the handled rats showed increases in the percentage of time spent in the open arms of the test apparatus, percentage of entries into open arms, and number of visits to the end of the open arms and decreases in the latency of the first open arm entry. Escape latency was lower in the handled rats compared with control rats in both the first and second trials. The data obtained suggest that handling decreases anxiety levels and improves learning skills and memory in rats.

Activated clotting time and heparin administration in Sprague-Dawley rats and Syrian golden hamsters.

To determine the activated clotting time (ACT) in rats and hamsters from our colony and to evaluate the response of this parameter to different heparin doses in these species, ACTs were measured using a Medtronic HemoTec ACT measurement system in samples obtained by intracardiac puncture from normal, nonanticoagulated, anesthetized rats and hamsters. Another groups of animals received different intravenous boluses of heparin to determine the dose needed to maintain ACT values > 480 sec for at least 30 min. The ACT (mean +/- SEM) was 48.0 +/- 2.17 sec for the 50 rats sampled and 42.5 +/- 2.35 sec for the 48 hamsters. Rats required a bolus of 1200 IU/kg intravenous heparin to maintain an ACT > 480 sec for 30 min; hamsters required 1000 IU/kg heparin for the same effect. We concluded that compared with humans, rats and hamsters from our colony have short ACTs and low sensitivity to heparin, in terms of the dose needed to reach a target ACT as well as the time required to sustain it. Further the ACT values in these animals showed great variability.

Metoclopramida inhibe la agregación plaquetaria inducida por ADP / Metoclopramide inhibit of the platelets aggregation induced by ADP

La metoclopramida reduce la presión arterial en sujetos normotensos e hipertenso durante estímulos presores moderados a severos pretratados con Labetalol, igualmente tiene efecto hipotensor en hipertensos durante urgencia hipertensiva y en anillos de aorta de rata ha mostrado un efecto antidrenérgico alfa 1. En el presente trabajo se reporta la inhibición de la agregación plaquetaria inducida por ADP en presencia de metoclopramida, hallazgo este que puede ser de importancia clínico-terapéutica en pacientes con preeclampsia en donde coexiste hipertensión arterial y actividad proagregante plaquetaria aumentada así como también niveles plasmáticos de serotonina elevados

Valores hematológicos, serológicos y peso de órganos en la rata Sprague-Dawley adulta / Hematological and serological values and organo weight in Sprague-Dawley adult rats

Sprague-Dawley rats are frequently used in experiments and their normal hematological, serological and anatomical parameters are not easily available. The aim of this study was to measure these parameters in adult Sprague-Dawley rats. 24 rats (12 males) whose weight ranged between 200 and 300 g raised at the Instituto de salud Pública in controlled environment conditions and fed with pellets were studied. After a 24 h fast animals were anesthetized with Droperidol and Ketamine and after obtaining a cardiac blood for glucose, calcium, amylase, total proteins, cholesterol, AST, ALT, bilirrubin, alkaline phosphatases, electrolytes and complete blood count were determined. Heart, lung, pancreas, kidney and testicle mean weight was also calculated. Male and female rats had significant differences in packed red cell volume, white blood cell count and hemoglobin

Investigation of the effects of extracts of Manilkara zapota (L.) P. van Royen on blood pressure and heart rate of rats

The objective of the study was to investigate the hypotensive effect produced by leaf extracts of Manilkara zapota. Methanol extracts of Manilkara zapota leaves were prepared using a soxhlet apparatus. The methanol was removed with a rotor evaporator. Sprague-Dawley rats were anaesthetized with urethane (1.2 mg/kb) and doses of 0.63, 1.25, 2.5, 5.0, 10.0 and 20.0 mg/kg body weight of extract were administered intavenously. Saline (0.9 percent) was given as a control. The effects on blood pressure and heart rate were recorded using a Pressure transducer (Spectramed model 23XL) coupled to a Grass polygraph (model 79E). The plant extract showed a dose-related hypotensive activity and no significant change in heart rate (P.0.05). Toxicity was observed with doses greater than 20mg/kg body weight. These results indicate that Manilkara zapota leaf tea used in folklore medicine to treat hypertension does indeed show various degrees of hypotensive activity when tested in lab animals. However, larger doses were toxic. It is therefore necessary to assess the beneficial as well as the adverse effects of this herb before usage by the hypertensive patient (AU)