Effect of chronic intracerebroventricular morphine to feeding responses in male rats.

Stainless steel cannulae were implanted stereotaxically in the third ventricle of male albino rats. The rats were fed with natural food pellets and water ad lib. After seven days of cannulation, daily body weight, food intake and water intake were recorded for the first five days, which was considered the preinjection control. Then increased and repetitive injections of morphine sulphate were administered intracerebroventricularly (ICV) in dosage of 30 micrograms/2 microliter, 45 micrograms/3 microliter, 60 micrograms/4 microliter, 75 micrograms/5 microliter, 90 micrograms/6 microliter and 105 micrograms/7 microliter on each following day respectively. In a separate set of experiments, the blood glucose levels were measured in animals injected with morphine to a dose corresponding to 15 micrograms/1 microliter, 30 micrograms/2 microliter, 45 micrograms/3 microliter, 60 micrograms/4 microliter and 75 micrograms/5 microliter on days 1, 2, 3, 4 and 5 respectively. Statistically significant (p less than 0.001) decreases in the body weight, food intake, water intake and increase in blood glucose were observed. The inferences derived from the above observations for the possible involvement and interaction of opioids in the regulation of feeding mechanisms have been discussed.