Simultaneous study of cerebral blood flow, vascular bed and deoxyglucose in aged rats. Effects of two dihydrogenated rye ergot alkaloids.

The influence of aging and the effects of treatment with dihydrogenated rye ergot alkaloid on cerebral hemodynamics and metabolism were studied in Long-Evans rats. Cerebral blood flow (CBF) was not affected by aging whereas the vascular bed and the uptake of deoxyglucose were significantly lower in aged than in young rats. 20 days after ligation of a carotid artery the blood flow on the same side of the brain, the vascular bed and the uptake of deoxyglucose were significantly lowered in aged rats as opposed to young rats. The second carotid artery was ligated 1 h before the animals were sacrificed: in the corresponding cerebral hemisphere the blood flow was found to be significantly lowered in young rats and even more so in aged rats. These results show that young rats are more likely to adapt to an acute or chronic circulatory deficiency than aged rats. Dihydroergocryptine ( DHEC , 0.1 mg/kg/day for 5 days, p.o.) reduces CBF and the vascular bed in aged rats, as opposed to dihydroergotoxine ( DHET , 5 X 0.1 mg/kg/day p.o.). The uptake of deoxyglucose was not influenced by the treatments. After ligation of the carotid arteries, treatment with DHEC and DHET induced an increase in CBF without any change in the vascular bed and, in the case of DHEC only, there was a significant increase in the uptake of deoxyglucose in the cerebral hemisphere submitted to acute circulatory deficiency. DHEC and DHET thus exerted significant effects on cerebral metabolism and hemodynamics in the aged rats after repeated oral treatment.