Centrophenoxine-induced increase of beta-adrenoceptor density in brain cortex of old mice

The influence of centrophenoxine treatment on beta-adrenoceptor density has been studied in the brain cortex of old mice. One group of 21-mth-old mice was injected intraperitoneally with 3.8 mg/day centrophenoxine daily for 5 days. A second group received the same daily treatment for 40 days. Two other groups of untreated mice of the same age served as controls. Receptor affinity showed no statistically significant changes in the four different groups investigated. As regards the receptor density, an increasing trend has been elicited between the 5-day treated mice and their controls; however, the increase was not statistically significant. The second group of old mice treated with centrophenoxine for 40 days exhibited a statistically significant increase in receptor density when compared with untreated animals. The modulation of beta-adrenoceptor density may be explained as the result of either a direct action on synaptic structure or an indirect effect mediated by thyroid hormones.