An orchestrated gene expression component of neuronal programmed cell death revealed by cDNA array analysis.

Programmed cell death (PCD) during neuronal development and disease has been shown to require de novo RNA synthesis. However, the time course and regulation of target genes is poorly understood. By using a brain-biased array of over 7,500 cDNAs, we profiled this gene expression component of PCD in cerebellar granule neurons challenged separately by potassium withdrawal, combined potassium and serum withdrawal, and kainic acid administration. We found that hundreds of genes were significantly regulated in discreet waves including known genes whose protein products are involved in PCD. A restricted set of genes was regulated by all models, providing evidence that signals inducing PCD can regulate large assemblages of genes (of which a restricted subset may be shared in multiple pathways).

Inhibition of lipopolysaccharide-induced pulmonary edema by isozyme-selective phosphodiesterase inhibitors in guinea pigs.

There is a need for pharmacological agents for the treatment of pulmonary edema associated with the adult respiratory distress syndrome. Therefore, we examined the effects of isozyme-selective cyclic AMP phosphodiesterase (cAMP PDE) inhibitors, as well as aminophylline and dexamethasone, on the pulmonary edema, protein leakage into the airways and airway neutrophilia induced by aerosolized lipopolysaccharide (LPS) in intact guinea pigs. Twenty-four hours after LPS exposure lung wet/dry weight ratios increased from 4.9 +/- 0.004 to 5.8 +/- 0.02. Rolipram (PDE4 selective), CI-930 (PDE3 selective), aminophylline and dexamethasone (given p.o. 1 hr before and 4 hr after LPS exposure) inhibited pulmonary edema formation with ED50 values of 1.7, 0.5, 31 and 2.8 mg/kg, respectively. Maximum inhibition occurred with rolipram at 10 mg/kg (70 +/- 17%), CI-930 at 10 mg/kg (101 +/- 4%), aminophylline at 50 mg/kg (88 +/- 14%) and dexamethasone at 3 mg/kg (64 +/- 6%). Denbufylline and milrinone also inhibited pulmonary edema formation at 10 mg/kg i.p., supporting the inhibition of PDE4 and PDE3 as the mechanisms of action of rolipram and CI-930, respectively. Rolipram, CI-930, aminophylline and dexamethasone (at maximum doses for inhibiting pulmonary edema) inhibited the 3-fold increase in bronchoalveolar lavage albumin concentration 24 hr after LPS exposure (42 +/- 14%, 98 +/- 2%, 70 +/- 9% and 53 +/- 13%, respectively). However, none of these compounds (at maximum doses for inhibiting pulmonary edema) inhibited the corresponding 400-fold increase in lavage neutrophil counts.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of antigen-induced pulmonary eosinophilia and neutrophilia by selective inhibitors of phosphodiesterase types 3 or 4 in Brown Norway rats.

Rolipram, a phosphodiesterase type 4 (PDE4)-selective inhibitor, has been demonstrated to inhibit antigen-induced pulmonary eosinophilia in guinea pigs and monkeys, suggesting that PDE4-selective inhibitors could be useful for treating asthma. Although the rat is used extensively in preclinical drug development, a pulmonary antiinflammatory effect of PDE4 inhibition has not been demonstrated in this species. Therefore, we examined the effects of rolipram, CI-930 (PDE3-selective inhibitor), zaprinast (PDE5-selective inhibitor) and aminophylline on antigen-induced pulmonary inflammatory cell influx in Brown Norway rats. Two weeks after sensitization rats were exposed to aerosolized ovalbumin and 24 h later bronchoalveolar lavage (BAL) was performed for determinations of total cell counts and cell type differentials. The resulting 10-fold increase in total cell counts was due primarily to an increase in eosinophils (from 0.06 to 11.0 x 10(6)) and neutrophils (from 0.02 to 12 x 10(6)). Rolipram, CI-930 and aminophylline, given p.o. before and after antigen challenge, each completely inhibited eosinophil influx, with B.I.D. ED50 values of 0.5, 0.4 and 39 mg/kg, respectively. Rolipram, CI-930 and aminophylline each completely inhibited neutrophil influx as well, with B.I.D. ED50 values of 0.1, 0.5 and 20 mg/kg, respectively. Denbufylline and milrinone (10 mg/kg p.o.) also inhibited eosinophil and neutrophil influx, consistent with PDE4 and PDE3 inhibition as the mechanisms of action of rolipram and CI-930, respectively. In contrast, zaprinast was inactive at 0.3-30 mg/kg. However, the beta2 agonist salbutamol greatly inhibited antigen-induced pulmonary eosinophilia and neutrophilia, with p.o. B.I.D. ED50 values of 2.1 and 2.3 mg/kg, respectively, indicating that drugs which increase intracellular cAMP levels by one of several mechanisms can inhibit antigen-induced pulmonary inflammation in rats. In conclusion, these results demonstrate that PDE4 inhibitors produce pulmonary antiinflammatory effects in rats. Furthermore, these results suggest that PDE3 inhibitors also can produce pulmonary antiinflammatory effects in vivo.

Leukotrienes mediate antigen-induced airway hyper-reactivity in guinea pigs.

The involvement of leukotrienes (LTs) in antigen-induced airway hyper-reactivity (AHR) was characterized pharmacologically by using several 5-lipoxygenase (5-LO) inhibitors and LTD4 antagonists in guinea pigs. AHR was evidenced by consistent and significant increases in sensitivity to bronchoconstriction induced by i.v. methacholine in anesthetized and ventilated animals 24 hr after a single ovalbumin aerosol challenge, but maximum methacholine-induced bronchoconstriction did not increase. Animals were pretreated with maximum doses of WY-50,295 tromethamine (WY-50,295), LY-171,883, MK-886 or zileuton, based upon inhibition of antigen-induced LT-dependent bronchoconstriction. WY-50,295, having a long duration of action, was the only compound that prevented AHR when given once before antigen challenge. However, LY-171,883 and MK-886 prevented AHR when a second dose was given 4 hr after challenge. Zileuton, having a short duration of action, failed to prevent AHR when given before and after challenge. The prevention of AHR did not result from functional antagonism (bronchodilation) by any compound. In bronchoalveolar lavage studies, neither WY-50,295 nor MK-886 inhibited the influx of eosinophils into the airways 24 hr after antigen challenge. The results provide pharmacological evidence that LTs play an important role in the pathogenesis of antigen-induced AHR in guinea pigs. Furthermore, the effectiveness of 5-LO inhibitors and LTD4 antagonists in this model depends upon a long duration of drug action and appears to result from inhibition of a direct airway effect of LTs rather than inhibition of eosinophil influx into the airways.(ABSTRACT TRUNCATED AT 250 WORDS)