Distinct Responses of Osphradial Neurons to Chemical Stimuli and Neurotransmitters in Lymnaea stagnalis L

• Published in: Cellular and molecular neurobiology 1999-04, Vol.19 (2), p.235-247
• Main Authors: Kamardin, N, Szucs, A, S.-Rozsa, K
• Format: Article
• Language: English
• Subjects: Lymnaea stagnalis
• ISSN: 0272-4340
• DOI: 10.1023/A:1006910211299

In Lymnaea stagnalis L. (Pulmonata, Basommatophora) the neurons in the osphradium were visualized by staining through the inner right parietal nerve by 5,6-carboxyfluorescein (5,6-CF). Three types of neurons were identified: three large ganglionic cells (GC1-3; 80-100 mu m), the small putative sensory neurons (SC; 20 mu m) and very small sensory cells (3-5 mu m). The ganglionic and putative sensory neurons were investigated by whole cell patch-clamp method in current-clamp condition. The three giant ganglionic neurons (GC1-3) located closely to the root of osphradial nerve, had a membrane potential (MP) between -30 and -70 mV and showed tonic or bursting activities. The small putative sensory cells (SCs) scattered throughout the osphradial ganglion, possessed a MP between -25 and -55 mV and showed an irregular firing pattern with membrane oscillations. At resting MP the GC1-3 cells were depolarized and increased the frequency of their firing, while the SCs were hyperpolarized and inhibited by NaCl (10 super(-2) M) and L-aspartate (10 super(-5) M) applied to the osphradium. 5-Hydroxytryptamine (5HT, 10 super(-6) M), gamma -aminobutyric acid (GABA; 10 super(-6) M) and the GABA sub(B) agonist baclofen (10 super(-6) M) depolarized the neurons GC1-3 and increased their firing frequency. In contrast, on the GC1-3 neurons, acetylcholine (Ach; 10 super(-6) M) and FMRFamide (10 super(-6) M) caused hyperpolarization and cessation of the firing activity.