RESUMEN
The brain of 17 asymptomatic normal adult beagles was evaluated with magnetic resonance imaging. Lateral ventricular size was quantified using computer algorithms. In beagles with large ventricles, contrast medium was introduced into the cerebellomedullary cistern to determine whether obstructive hydrocephalus was present. Total lateral ventricular volume ranged from 77 mm3 to 11,726 mm3. Based on Gd-DTPA diffusion, the CSF flow pattern was considered normal and normal neural morphology was seen using electron microscopy. Results suggest a high incidence of clinically asymptomatic ventriculomegaly in normal adult beagles.
Asunto(s)
Ventrículos Cerebrales/patología , Enfermedades de los Perros/diagnóstico , Hidrocefalia/veterinaria , Imagen por Resonancia Magnética/veterinaria , Animales , Ventrículos Cerebrales/ultraestructura , Medios de Contraste , Enfermedades de los Perros/patología , Perros , Gadolinio , Gadolinio DTPA , Hidrocefalia/diagnóstico , Compuestos Organometálicos , Ácido Pentético/análogos & derivadosRESUMEN
A method for measuring activity of hamsters using a stabilimeter at a 1 second sampling rate with data computer recorded as 5 minutes integrated values was developed. In a single cage without a running wheel a consistent pattern for activity was observed, consisting of (a) low levels of daytime activity until one or two hours before lights off when activity increased significantly; and (b) a peak of nocturnal activity in the first hour of the dark cycle. The inclusion of a running wheel increased and altered significantly the pattern of nocturnal activity. In further experiments animals were housed in two linked cages, one acting as light-proof burrow and the other exposed to light. Measurements were recorded from each cage independently and from two position detectors in the interconnecting tunnel. The results showed: (a) total activity, i.e., the summation of activity in both cages, was not different from activity in a single cage system; (b) low daytime activity was composed of prolonged periods of rest in the burrow plus short periods of activity in the exposed cage; the increased activity one hour before lights off was localised to the light-proof burrow; and (c) after lights off, the animals began to spend increasing periods of time in the exposed cage reaching a maximum after one hour. Replacing artificial with natural light did not change the principal features of behaviour.
Asunto(s)
Ritmo Circadiano , Vivienda para Animales , Actividad Motora , Medio Social , Animales , Cricetinae , Luz , Masculino , MesocricetusRESUMEN
To investigate the motor rhythm of the Syrian hamster under natural photoperiod and to relate these findings to pineal rhythm, animals were left undisturbed in metabolic cages in which stabilimeter systems registered motor activity, photovoltaic cells registered light intensity, and in which urinary output was used for the assay of the major melatonin metabolite 6-sulphatoxymelatonin. The motor activity of two animals was monitored during 1 month and showed a striking similarity. Melatonin secretion was measured during 3 consecutive days and showed a night/day ratio in both animals that was relatively constant and that was coupled to the diurnal rhythm of the animals' activity.