Effects of adrenergic agents on locomotor behavior and reproductive development in Drosophila

Inhibition of tyrosine hydroxylase, the rate-limiting enzyme in catecholami ne biosynthesis, by alpha-methyl-p-tyrosine (alpha MT) at media concentrati ons of 0.3-3.0 mM, markedly inhibited (>90%) fly reproduction and developme nt as evidenced by progeny count. Under these conditions adult spontaneous locomotor activity (SMA) was also dose-dependently reduced. However, no sig nificant effects on behavior were observed at 0.3 mM. The behavioral effect s of alpha MT were prevented by coadministration of L-DOPA. Similar effects on behavior and development were produced by reserpine at doses of 0.1-1.0 mM. The higher doses affected behavior, but no behavioral effects occurred at 0.1 mM. Rescue from the effects of reserpine was also achieved with L-D OPA. Treatment at 1 mM with the mammalian catecholamine receptor blockers p ropranolol (beta(1)beta(2)), raclopride (D-2), SK&F 83566 (D-1), prazosin ( alpha(1)), and rauwolscine (alpha(2)) did not affect behavior. The two alph a adrenoceptor inhibitors, however, markedly decreased fly development. The se results suggest that the receptor mechanisms mediating the effects of ca techolamines on behavior and development are different. The locomotor behav ior of adult progeny of parents treated with the lowest doses of alpha MT a nd reserpine described above was markedly suppressed by these drug treatmen ts. This result indicates an increased sensitivity of the progeny to compou nds which share the ability to deplete tissue catecholamines. Thus, alterat ions in catecholamine function during development may have behavioral conse quences in surviving organisms. (C) 2000 Wiley-Liss, Inc.