RESUMO
The structural and functional changes of the three identified neurons of the small parietal ganglion were investigated during experiments on the mollusc Lymnaea stagnalis, in two age groups: adult (10-12 months) and old (22-24 months). Old molluscan neurons showed, along with the destructive changes (destruction of mitochondrial cristae, formation of autophagosomes, residual bodies, etc.), the appearance of important adaptive mechanisms (hypertrophy of the mitochondria, hyperplasia of the Golgi apparatus, increased area of nuclear membranes). With aging no changes have been observed in the values of membrane potential, resistance of the neuronal membrane, amplitude and duration of action potential. Considerable changes have been noticed in the values of excitability, frequency of the impulse activity, rate of decrease of the posterior action potential front, and its trace hyperpolarization in the neurons from 22-24-month-old molluscs. The sensitivity of the molluscan neuronal membrane to acetylcholine, norepinephrine and serotonin increased with age.
