Effects of clonidine and guanfacine on drinking and ambulation in spontaneously hypertensive rats

Present experiment was undertaken to compare the effects of clonidine and guanfacine on water drinking behavior and ambulatory activity in spontaneously hypertensive rats (SHR). Equipotent hypotensive doses of clonidine and guanfacine, 150 micrograms/kg and 1500 micrograms/kg, respectively, given twice a day at 8:00 and 20:00, produced a triphasic pattern of behavioral changes; initial increase in water drinking and ambulation during the light period, decrease in water intake and ambulation at the beginning of the dark period, and a second increase in water drinking and ambulation at the end of the dark period. Guanfacine treated SHR showed less change in water drinking behavior and ambulation than the clonidine treated SHR.