Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA.
Learn Mem. 2011 Dec 21;19(1):26-34. doi: 10.1101/lm.024802.111. Print 2012 Jan.
Heterotrimeric G(o) is an abundant brain protein required for negatively reinforced short-term associative olfactory memory in Drosophila. G(o) is the only known substrate of the S1 subunit of pertussis toxin (PTX) in fly, and acute expression of PTX within the mushroom body neurons (MB) induces a reversible deficit in associative olfactory memory. We demonstrate here that the induction of PTX within the α/β and γ lobe MB neurons leads to impaired memory acquisition without affecting memory stability. The induction of PTX within these MB neurons also leads to a significant defect in an optimized positively reinforced short-term memory paradigm; however, this PTX-induced learning deficit is noticeably less severe than found with the negatively reinforced paradigm. Both negatively and positively reinforced memory phenotypes are rescued by the constitutive expression of G(o)α transgenes bearing the Cys(351)Ile mutation. Since this mutation renders the G(o) molecule insensitive to PTX, the results isolate the effect of PTX on both forms of olfactory associative learning to the inhibition of the G(o) activation.
三聚体 G(o) 是一种丰富的脑蛋白，对于果蝇的负强化短期联想嗅觉记忆是必需的。G(o) 是在果蝇中百日咳毒素（PTX）S1 亚单位的唯一已知底物，并且在蘑菇体神经元（MB）中急性表达 PTX 会导致联想嗅觉记忆的可逆缺陷。我们在这里证明，在 α/β 和 γ 叶 MB 神经元中诱导 PTX 会导致记忆获取受损，而不会影响记忆稳定性。在这些 MB 神经元中诱导 PTX 也会导致优化的正强化短期记忆范式中的显著缺陷；然而，与负强化范式相比，这种 PTX 诱导的学习缺陷明显较轻。通过表达携带 Cys(351)Ile 突变的 G(o)α 转基因的组成型表达，可挽救负强化和正强化记忆表型。由于这种突变使 G(o) 分子对 PTX 不敏感，因此这些结果将 PTX 对两种形式的嗅觉联想学习的影响隔离到 G(o) 激活的抑制。
