Localization of serotonin transporter mRNA in the CNS of Lymnaea stagnalis

The serotonin transporter, SERT, is reported as a key molecule that regulates serotonergic neurotransmission. In the present study, we analyzed the localization of Lymnaea SERT (LymSERT) mRNA-containing neurons by in situ hybridization using frozen sections of the central nervous system (CNS) of Lymnaea . To precisely demonstrate the distribution of LymSERT mRNA-containing neurons, colocalization with serotonin immunoreactivity was also examined. The results showed that LymSERT mRNA was constitutively expressed and localized in the serotonin-containing neurons in the CNS

Potassium channels in the Helix central nervous system: Preliminary immunohistochemical studies

Distribution of the potassium channel of Kv4.3 type was investigated in the central nervous system (CNS) of Helix pomatia by immunohistochemistry. Immunopositive neurons were found widely distributed in the CNS, present mostly in smaller groups in the different central ganglia but not in the visceral ganglion. Labeled fibers were characteristic for not only the neuropils of all ganglia but also the connective tissue sheath around the CNS and the aorta wall were richly innervated. Western blot analysis revealed a clear identity with the mammalian Kv4.3 subunit, suggesting an evolutionary conserved structure of this channel type. Our preliminary results provide a steady basis for further experiments aiming partly at the identification of other potassium channel types and partly the ultrastructural localization of Kv4.3

Immunodetection and localization of nitric oxide synthase in the olfactory center of the terrestrial snail, Helix pomatia

The procerebrum of stylommatophoran snails produces nitric oxide (NO)-modulated oscillatory local field potentials which are considered the basis of olfactory information processing. Although the function of NO is well characterized in the PC, the identification and distribution of NO synthase (NOS) has not known completely. In the present study, applying a mammalian anti-NOS antibody, a 170 kDa molecular weight NOS-like protein was demonstrated in the procerebrum homogenate of Helix pomatia. NOS-like immunolabeling of the globuli cells, the internal and terminal neuropils displayed an identical distribution compared to that of NADPH-diaphorase reactive material, confirming the specificity of immunohistochemistry. The detailed characteristics of the immunostaining (different intensity of the neural perikarya, a gradual appearance in the terminal neuropil and in the axon bundles of the tentacular nerve, as well as an intense, homogeneous distribution of NOS-like immunoreactivity in the internal neuropil) suggest that NOS is expressed constitutively, maintaining a high level of the enzyme in neuropil areas. NOS accumulation in the internal neuropil suggests that NO plays an important role in delivering olfactory signals extrinsic to the procerebrum, and integrating them with other sensory modalities, respectively. Our results are the first, demonstrating unequivocally the presence of NOS and resolving its differential distribution in the Helix procerebrum

Immunological and pharmacological identification of the dopamine D1 receptor in the CNS of the pond snail, Lymnaea stagnalis

We investigated the presence and distribution of the D1 dopamine receptor in the CNS of Lymnaea stagnalis applying immunobloting and immunocytochemistry. We also investigated the effect of dopamine as well as the specific D1 receptor blocker, SCH23390, on the firing activity of the feeding modulator serotonergic neuron, CGC, which displayed D1 immunoreactivity. Immunoblot experiments showed one specifically labeled band with 62 kDa mw which is close to that of the mammalian D1 receptor. Neurons displaying D1-like immunoreactivity can be observed in each ganglion of the CNS but particularly in the pedal ganglia which are the center for locomotion. Dopamine regularly evokes burst activity in the serotonergic CGC at 1 mM and this effect could be antagonized by SCH23390. These observations suggest that a D1-like receptor molecule is present in the CNS of Lymnaea