Shigeto Kitamura

Actions of adenosine A2A receptor antagonist KW-6002 on drug-induced catalepsy and hypokinesia caused by reserpine or MPTP.

Abstract Rationale: Current treatment of Parkinson’s disease (PD) is based on dopamine replacement therapy, but this leads to long term complications, including dyskinesia. Adenosine A2A receptors are particularly abundant in the striatum and would be a target for an alternative approach to the treatment of PD. Objectives: The purpose of this study is to examine the efficacy and potency of the novel selective adenosine A2A receptor antagonist (E)-1,3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dhydro-1H-purine-2,6-dione (KW-6002) in ameliorating the motor deficits in various mouse models of Parkinson’s disease. Methods: We evaluated the efficacy and potency of KW-6002 and other reference compounds in the selective adenosine A2A receptor agonist 2-[p-(2-carboxyethyl)phenethylamino]-5’-N-ethylcarboxamidoadenosine (CGS 21680)-, haloperidol- or reserpine-induced catalepsy models. The effect of KW-6002 on reserpine or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride(MPTP)-induced hypolocomotion was also examined. Results: The ED50s of KW-6002 in the reversal of CGS21680-induced and reserpine-induced catalepsy were 0.05 mg/kg, PO and 0.26 mg/kg, PO, respectively. Compared to the ED50 of other adenosine antagonists and dopamine agonist drugs, KW-6002 is over 10 times as potent in these models. KW-6002 also ameliorated the hypolocomotion (minimum effective dose; 0.16 mg/kg) induced by nigral dopaminergic dysfunction with MPTP or reserpine treatment. Combined administrations of subthreshold doses of KW-6002 and l-dopa (50 mg/kg, PO) exerted prominent effects on haloperidol-induced and reserpine-induced catalepsy, suggesting that there may be a synergism between the adenosine A2A receptor antagonist KW-6002 and dopaminergic agents. Conclusions: To our knowledge, KW-6002 is the most potent and orally active adenosine A2A receptor antagonist in experimental models of Parkinson’s disease, and may offer a new therapeutic approach to the treatment of Parkinson’s disease.

Effects of KW-4679, a New Orally Active Antiallergic Drug, on Antigen-Induced Bronchial Hyperresponsiveness, Airway Inflammation and Immediate and Late Asthmatic Responses in Guinea Pigs

We investigated the effects of KW-4679, an antiallergic drug, on the development of bronchial hyperresponsiveness, airway inflammation and early and late asthmatic responses following aerosol antigen challenge in guinea pigs actively sensitized by the inhalation of aerosolized ovalbumin. Pretreatment with KW-4679 (10 mg/kg, p.o.) 1 h before antigen challenge prevented the development of bronchial hyperresponsiveness to inhaled methacholine. Examination of the bronchoalveolar lavage fluid 24 h after antigen challenge revealed the inhibitory effect of KW-4679 on the infiltration of eosinophils into the airway. Treatment with KW-4679 significantly inhibited both the immediate and late asthmatic responses. These results indicate that KW-4679 could be useful in the treatment of allergic diseases such as bronchial asthma.