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Abstract

The aminergic innervation of the foot of Lymnaea stagnalis was investigated using electron microscopy, immunocytochemistry, and HPLC. The foot was found to contain large amounts of serotonin and dopamine, though at lower concentrations than are found in nervous tissue. Serotonin containing tissue was concentrated in the ventral surface of the foot, under ciliated areas of the epidermis where it occurred in varicosities, with fine tracts joining these varicosities. Varicosities also occurred in deeper tissues, probably adjacent to mucus cells. Positive fluorescence for serotonin in axons was found in nerves innervating the foot, but few neuronal cell bodies containing serotonin were detected, indicating that most of the innervation was coming from the central ganglia. Axon varicosities were found using TEM on ciliated cells, mucus cells, and muscle cells as well as interaxonal junctions (possibly non-synaptic) within nerves. The neuronal varicosities contacting the ciliated cells and mucus cells contained mostly dense-cored vesicles of between 60 and 100 nm in diameter. Smaller, lucent vesicles also occurred in these terminals. The origin and significance of this innervation is discussed. It is suggested that both serotonin and dopamine may play a large role in controlling ciliary gliding by the foot.

Transcription factors lhx1/5-1 and pitx are required for the maintenance and regeneration of serotonergic neurons in planarians

“…Similar to planarian locomotion, the pond snail Lymnea stagnalis uses a ciliated epidermis to glide across surfaces, and it has been shown that the multiciliated epidermal cells of the snail foot organ are directly innervated with serotonin-containing axon tracts (McKenzie et al, 1998). Direct serotonergic innervation of ciliated epithelial tissues is also observed in the embryo of another pond snail, Helisoma trivolvis, in which serotonin release acts to increase the beat frequency of the associated motile cilia (Koss et al, 2003;Kuang et al, 2002).…”

Determination of cilium power on the foot sole of the freshwater snail Lymnaea stagnalis

“…When counting the cilia, we based on the assump tion that densely located cilia [12] uniformly covered the foot sole [14]. Since the foot sole also houses out lets of the goblet cell, as well as villus and intercalary cells [7,14], we assumed that sole area covered with cilia would amount to 90% of S s .…”

“…Since the foot sole also houses out lets of the goblet cell, as well as villus and intercalary cells [7,14], we assumed that sole area covered with cilia would amount to 90% of S s . S s ' S c was found with the help of electron microscopy.…”

Sense and Insensibility – An Appraisal of the Effects of Clinical Anesthetics on Gastropod and Cephalopod Molluscs as a Step to Improved Welfare of Cephalopods

“…At a behavioral level the terrestrial pulmonate Cepaea nemoralis has been shown to develop tolerance to morphine induced analgesia (Kavaliers and Hirst, 1986), but required specific environmental cues for the tolerance to be expressed, consistent with a classical conditioning of habituation model. The activity of the serotonergic ciliomotor neurons (PeA clusters) of Lymnaea stagnalis (Syed and Winlow, 1989; McKenzie et al, 1998) is suppressed in the presence of the opiate antagonist naloxone resulting in a decrease in the rate of ciliary locomotion, whereas opiate agonists such as morphine accelerated the synaptically driven firing of the PeA neurons in vivo (D’iakonova, 1998). Voltage clamp studies by Vislobokov and Savos’kin (2000) on the opioid analgesics morphine, promedol, tramadol, and butorphanol indicate that sodium and potassium currents in Lymnaea neurons in vivo are reversibly inhibited and non-specific leak currents are reduced, thus stabilizing the cell membrane.…”