RT Journal Article
SR Electronic
T1 α<sub>1</sub> and β<sub>2</sub> Adrenoreceptor Agonists Inhibit Pentylenetetrazole-Induced Seizures in Mice Lacking Norepinephrine
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 1042
OP 1048
VO 298
IS 3
A1 David Weinshenker
A1 Patricia Szot
A1 Nicole S. Miller
A1 Richard D. Palmiter
YR 2001
UL http://jpet.aspetjournals.org/content/298/3/1042.abstract
AB It has been known for many years that norepinephrine (NE) is a potent endogenous anticonvulsant, yet there is confusion as to which receptor(s) mediate this effect. This is probably due to multiple factors, including the importance of distinct signaling pathways for different seizure paradigms, a lack of comprehensive pharmacological studies, and difficulty in interpreting existing pharmacological results due to the presence of endogenous NE. We sought to circumvent these problems by testing the anticonvulsant activity of selective agonists for most known adrenoreceptors (ARs) in dopamine β-hydroxylase knockout (Dbh −/−) mice that lack endogenous NE. Dbh −/− mice are hypersensitive to pentylenetetrazole (PTZ)-induced seizures, demonstrating that endogenous NE inhibits PTZ-induced seizures in the wild type. Pretreatment of Dbh −/− mice with an α1AR or β2AR, but not an α2AR or β1AR agonist significantly protected against PTZ-induced seizures. In contrast, only the β2AR agonist showed anticonvulsant activity in heterozygous controls. Furthermore, an α1AR antagonist exacerbated PTZ-induced seizures in control mice, whereas a β2AR antagonist had no effect. We conclude that activation of the α1AR is primarily responsible for the anticonvulsant activity of endogenous NE in the murine PTZ model of epilepsy. Endogenous NE probably does not activate the β2AR under these conditions, but exogenous activation of the β2AR produces an anticonvulsant effect. The American Society for Pharmacology and Experimental Therapeutics