Age related changes in the inhibitory effect of clonidine on high K+-evoked noradrenaline release from brain slices of rats.
The effects of clonidine on a high K+-induced release of noradrenaline (NA) were studied in 70-d- and 2-year-old rats. Treatment with 0.1 and 1.0 microM clonidine significantly (p less than 0.01) inhibited 20 mM KCl-evoked L-[3H]NA release from cerebral cortical slices in 70-d-old rats. The amounts of high K+-evoked L-[3H]NA release were markedly decreased at 2 years, compared to that at 70 d. In addition, the inhibitory effects of clonidine on high K+-evoked L-[3H]NA release were no longer observed in 2-year-old animals. These results suggested that presynaptic functions, including the modulation of NA release by alpha 2-adrenoceptors, could become low in the brains of the 2-year-old rats.
Qi
S B
SB
Department of Pharmacology, Toyama Medical and Pharmaceutical University, Japan.
Nomura
Y
Y
D000375:Aging / Q000378:metabolism*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism; D003000:Clonidine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects
D011942:Receptors, Adrenergic, alpha; D003000:Clonidine; D011188:Potassium; D009638:Norepinephrine