Effects of calcium channel antagonists on the corpora allata of adult male loreyi leafworm Mythimna loreyi: Juvenile hormone acids release and intracellular calcium level

Abstract

The effects of voltage-dependent calcium channel (VDCC) antagonists and the non-specific calcium channel antagonists on both juvenile hormone acids (JHA) release and cytosolic free calcium concentration ([Ca2+]i) are investigated in the corpora allata (CA) of the adult males loreyi leafworm Mythimna loreyi. The VDCC antagonists used in this study are: the L-type antagonists diltiazem, nifedipine, and verapamil, the N-type antagonist omega-Conotoxin (CgTx) GVIA, the N- and P/Q-type antagonist omega-CgTx MVIIC, and the T-type antagonist amiloride. The non-specific calcium channel antagonists used in this study were cadmium (Cd2+), cobalt (Co2+), nickle (Ni2+), and lanthanum (La3+). The results show that both the DHPs-sensitive L-type antagonist nifedipine and the N-type antagonist omega-CgTx GVIA were able to inhibit JHA release, but only omega-CgTx GVIA was able to reduce the [Ca2+]i. Among the non-specific calcium channel antagonists, Cd2+ is the most potent in reducing JHA release but without obvious effect on the [Ca2+]i, La3+ significantly increases the [Ca2+]i but without effect on JHA release.

Cadmium and Its Neurotoxic Effects

“…This study addition of inorganic Ca 2+ channel blockers (Cd 2+ or Co 2+ ) was used to demonstrate the Ca 2+ dependence of  Ca 2+ -activated k + currents [94]. Cd 2+ and Co 2+ were the nonspecific calcium channel antagonists in the study [95, 96]. Co 2+ did not modify significantly the ATP-evoked current [97].…”

Pharmacological characterisation of voltage-dependent Ca2+ channels in isolated ganglia from the myenteric plexus

“…The non-specific Ca 2+ channel blockers Ni 2+ and Co 2+ (for reference see Hsieh et al, 2001) induced a significant decrease in the fluorescence ratio, indicating a decline of [Ca 2+ ] i . A first significant inhibition was observed at a concentration of 5 Â 10 À 4 mol l À 1 (Fig.…”

Regulation of Drosophila Long-Term Courtship Memory by Ecdysis Triggering Hormone

“…Since we have demonstrated that the ETH-JH signaling cascade is required for courtship LTM and that augmented Inka cell activity during the training session improves LTM performance (Figure 1), we also asked whether augmented CA activity through expression of dTrpA1 would enhance courtship LTM via increased JH levels. Previous studies showed that Ca 2+ influx induces biosynthesis and release of JH in the CA (Kikukawa et al, 1987;Yamamoto et al, 1988;Allen et al, 1992;Hsieh et al, 2001;Chiang et al, 2002). We expressed dTrpA1 in the CA using the JHAMT-GAL4 driver, since this would be expected to depolarize CA cells.…”