Influence of HgCl2 on the osphradial multisensory system of Lymnaea stagnalis L.

The osphradial multisensory system of Lymnaea stagnalis L. (Pulmonata, Baso mmatophora) was used to demonstrate the modulation of chemosensory informat ion both at periphery and central nervous system (CNS) following heavy meta l treatments. A semi-intact preparation including osphradium, CNS and the right inner par ietal nerve (r.i.p.n.) connecting them was used to record both extracellula r activity of nerve and intracellular activity of central neurons receiving information from osphradium. The ion currents of osphradium were recorded using patch-clamp method. The changes in nerve and neuronal activity were e xpressed by averaging of firing frequency and interspike intervals. The che mosensory function of osphradium was shown by application of L-aspartate, u rea, saccharose and stagnant water to its surface. The central neurons reac ting to the stimulation of osphradium were located to visceral, right parie tal, pedal and cerebral ganglia of Lymnaea. Both the acute and chronic treatments with HgCl2 damaged the sensory functi on of osphradium traced on the flow of information from periphery to centra l neurons. At the same time, mercury chloride modified the synaptic connect ions of respiratory pattern generators as well as the Ca- and K-dependent i on currents of osphradial neurons. The results proved the multisensory role of osphradium sensing the alterati ons in the environment and its usefulness in monitoring the effects of poll utants at various level of regulation from chemosensory epithelium to CNS.