Role of aminergic (serotonin and dopamine) systems in the embryogenesis and different embryonic behaviors of the pond snail, Lymnaea stagnalis.

A detailed biochemical and pharmacological analysis of the dopaminergic (DAergic) and serotonergic (5-HTergic) systems was performed during the embryogenesis of Lymnaea stagnalis, to monitor their role in development and different behaviors. The dopamine (DA) level and the synthesizing decarboxylase enzyme activity showed a continuous increase, whereas the serotonin (5-HT) concentration remained low until late postmetamorphic development, when they all showed a rapid and significant increase. Application of monoamine precursors increased, whereas enzyme inhibitors and neurotoxins reduced monoamine levels; all treatments resulting in a prolongation of embryogenesis. Following, p-chlorphenylalanine (pCPA) and 3-hydroxybenzylhydrazine (Nsd-1015) treatments, no 5-HT immunoreactivity could be detected in the embryonic nervous system. These findings suggest that changes of monoamine levels in either (negative or positive) direction cause slowing of embryogenesis. Embryonic rotation and radula protrusion rate was enhanced following both serotonin and dopamine application, whereas frequency of gliding was increased by serotonin treatment. These results clearly indicate the involvement of 5-HT and DA in the regulation of a broad range of embryonic behaviors. Pharmacological characterization of a 5-HT receptor associated with the L. stagnalis embryonic behaviors studied revealed that a mammalian 5-HT(1)-like receptor type is involved in the 5-HTergic regulation of locomotion activity.

Effects of Cu(2+) and Pb(2+) on different fish species: liver cytochrome P450-dependent monooxygenase activities and FTIR spectra.

The effects of Cu(2+)-sulfate and Pb(2+)-acetate on carp (Cyprinus carpio L.), silver carp (Hypopthalmichtys molitrix V.) and wels (Silurus glanis L.) were studied. The liver microsomal Cyt P450 content, the EROD, ECOD and APND monooxygenase activities were measured. In vivo treatment with 1 mg L(-1) Cu(2+) significantly elevated the activities of these enzymes and Cyt P450 content in silver carp livers. The high-dose Cu(2+) treatment (10 mg L(-1)) on silver carp caused two-fold higher induction in the P450 dependent monooxygenase isoensymes than in wels. Although the 2 mg kg(-1) treatment with Pb(2+) in carp elevated significantly the P450 content, the EROD isoenzyme activities were significantly decreased after 1 day, showing the destructive effect of metal ion on the enzyme system. In vitro, Cu(2+) and Pb(2+) decreased the Cyt P450 content in the carp liver microsomes and the absorption peak shifted to higher wavelength. Fourier Transform Infrared (FTIR) spectroscopy was used to detect the damaging effects of the heavy metals. According to the inhibitory potency to Cu(2+), the most sensitive isoenzyme was the EROD in wels, the least was the silver carp's isoenzyme. The investigated fish P450 isoenzymes showed, that the Cu(2+) was a stronger inhibitor than Pb(2+).

Serotonergic and dopaminergic influence of the duration of embryogenesis and intracapsular locomotion of Lymnaea stagnalis L.

The role of the dopaminergic and serotonergic system was studied during the embryonic development of the pond snail Lymnaea stagnalis, with special attention to the effect of dopamine and serotonin as well as their agonists and antagonists on the rotation of the veliger larvae, and to the effect of precursors and inhibitors of the synthetizing enzymes on the duration of the embryonic life. Serotonin, D-lysergic acid diethylamide and N,N-dimethyltryptamine increased at a concentration of 1 microM the rotation by 50%, 90% and 87% respectively, and among them D-Lysergic acid diethylamide was found to be the most potent agonist. Other serotonergic agonists and antagonists enhanced the frequency of the rotation (from 165% to 355%) at higher threshold concentrations in the following rank order: methysergid > tryptamine > 2,5-dimethoxy-4-iodoamphetamine > 5-carboxyamidotryptamine > bromo-lysergic acid diethylamide > 7-methyltryptamine. Application of 1-(2-methoxyphenyl) piperazine decreased the rotation by 76%. The reuptake inhibitor desipramine completely blocked the rotation and killed the embryos. Dopaminergic agonists accelerated the rotation by 62% to 233%, and their effect was ranged as follows: dopamine > apomorphine > m-tyramine approximately equal to p-tyramine. Chlorpromazine at 100 microM concentration killed the embryos. At a concentration of 100 microg/ml, tyrosine, the precursor of DA, slowed down the embryonic development by increasing the duration of the embryonic life from 8 to 10 days. Decarboxylase inhibitors, alpha-methyl-3,4-dihydroxyphenyl-alanine (25 microg/ml) and m-hydroxybenzylhydrazin (5 microg/ml), killed 50% of the embryos, meanwhile the rest hatched ten days later, compared to the control animals. The development was partially blocked by the serotonin precusor L-tryptophane (50 microg/ml). Trytophan hydroxylase blocker, p-chlorphenylalanine (50 microg/ml) resulted in a distortion of the body pattern of the embryos, and prevented the hatching of most (95%) of the animals.