Fong P P
Biol Bull. 1998 Apr;194(2):143-149. doi: 10.2307/1543044.
Serotonin (5-hydroxytryptamine, 5-HT) and its receptor ligands induce both oocyte maturation and spawning in zebra mussels (Dreissena polymorpha). The selective serotonin reuptake inhibitors (SSRIs) fluvoxamine ("Luvox"), fluoxetine ("Prozac"), and paroxetine ("Paxil") are commonly prescribed drugs for the treatment of depression in humans. They act to increase 5-HT neurotransmission by inhibiting reuptake transport proteins at synapses. I tested the efficacy of these drugs at inducing spawning in zebra mussels. All three compounds induced spawning in both sexes at concentrations lower than that for 5-HT itself. Fluvoxamine was particularly potent, inducing spawning in 100% of both sexes at 10-5 and 10-6 M. The concentration that induced a significant percentage of animals to spawn was as low as 10-9 M for males and and 10-7 M for females. The lowest concentration of fluvoxamine to induce spawning was 10-8 M for females (40%) and 10-10 M for males (20%). Gametes spawned in fluvoxamine (10-5 M and lower) were viable, and swimming trochophores were formed within 20 hours. Fluoxetine was also an effective spawning inducer, causing 100% of males to spawn at 5 x 10-6 M. The concentration of fluoxetine required to induce a significant percentage of spawning was as low as 5 x 10-8 M for males and 5 x 10-6 M for females. In both fluvoxamine and fluoxetine, more than 60% of the males spawned within the first hour of exposure. In contrast, paroxetine was a weak spawning inducer. At concentrations of 10-5 and 10-6 M it induced significant, but low (50% and 40%, respectively) percentages of males to spawn. Paroxetine did not induce significant spawning in females. Thus, fluvoxamine, fluoxetine, and paroxetine can induce spawning at low concentrations, and fluvoxamine is the most powerful spawning inducer in any bivalve. These may be useful agents for stimulating invertebrate serotonergic mechanisms without applying exogenous 5-HT, and they are potentially important in bivalve aquaculture. Moreover, these results suggest, for the first time, the presence of 5-HT reuptake transporters in bivalve molluscs.
血清素（5-羟色胺，5-HT）及其受体配体可诱导斑马贻贝（多形饰贝）的卵母细胞成熟和产卵。选择性血清素再摄取抑制剂（SSRIs）氟伏沙明（“Luvox”）、氟西汀（“Prozac”）和帕罗西汀（“Paxil”）是常用于治疗人类抑郁症的药物。它们通过抑制突触处的再摄取转运蛋白来增加5-HT神经传递。我测试了这些药物诱导斑马贻贝产卵的效果。所有这三种化合物在低于5-HT自身浓度时就能诱导雌雄两性产卵。氟伏沙明尤其有效，在10⁻⁵和10⁻⁶ M浓度下能使100%的雌雄个体产卵。诱导相当比例动物产卵的浓度，对雄性低至10⁻⁹ M，对雌性为10⁻⁷ M。氟伏沙明诱导产卵的最低浓度，对雌性是10⁻⁸ M（40%），对雄性是10⁻¹⁰ M（20%）。在氟伏沙明（10⁻⁵ M及更低浓度）中产出的配子是有活力的，并且在20小时内形成了游动的担轮幼虫。氟西汀也是一种有效的产卵诱导剂，在5×10⁻⁶ M浓度下能使100%的雄性产卵。诱导相当比例产卵所需的氟西汀浓度，对雄性低至5×10⁻⁸ M，对雌性为5×10⁻⁶ M。在氟伏沙明和氟西汀中，超过60%的雄性在暴露的第一小时内就产卵了。相比之下，帕罗西汀是一种较弱的产卵诱导剂。在10⁻⁵和10⁻⁶ M浓度下，它能诱导相当比例（分别为50%和40%）的雄性产卵，但比例较低。帕罗西汀在雌性中未诱导出显著的产卵现象。因此，氟伏沙明、氟西汀和帕罗西汀能以低浓度诱导产卵，且氟伏沙明是所有双壳贝类中最有效的产卵诱导剂。这些可能是在不应用外源性血清素的情况下刺激无脊椎动物血清素能机制的有用试剂，并且它们在双壳贝类水产养殖中可能具有重要意义。此外，这些结果首次表明双壳贝类软体动物中存在血清素再摄取转运体。
