For our studies we use the pond snail, Lymnaea stagnalis, which has a simple nervous system containing large, reproducibly identifiable neurones. These neurones form simple circuits that control readily quantifiable behaviours allowing us to relate age-dependent changes in behaviour to changes in the properties of individual neurones. We find that there isn't a general deterioration of snail neurones with age, but identifiable defects develop in specific neurones. We are one of the first groups to study ageing using the snail in this way. The work described below was carried out in collaboration with Imperial College.
We are the first group to examine how age affects the properties of central pattern generating circuits (see two publications below). This worked showed that, with increasing age, the basic rhythm generating circuit was still intact but changes were observed in a pair of serotonergic modulatory neurones whose role is to control the ability of food to gate a feeding rhythm and also to regulate the frequency of the rhythm. Both functions were impaired with increasing age causing fewer animals to respond to a feeding stimulus and those which did respond had feeding rhythms that were much slower than their young counterparts.
1. B.A. Patel, M. Arundell, M.C. Allen, P. Gard, D. O’Hare, K. Parker and M.S. Yeoman, Changes in the properties of the modulatory cerebral giant cells contribute to aging in the feeding system of Lymnaea. Neurobiol Aging. 2006 Dec;27(12):1892-901. 2. M. Arundell, B.A. Patel, V. Straub, M.C. Allen, C. Janse, D. O’Hare, K. Parker, P.R.Gard and M.S. Yeoman, Effects of age on feeding behavior and chemosensory processing in the pond snail, Lymnaea stagnalis. Neurobiol Aging. 2006 Dec;27(12):1880-91.
Nitric oxide is a key neuronal signalling molecule in snails and humans
We are the first group to detect the release of nitric oxide (NO) from single neurones; this work was done in collaboration with Imperial College.
This work is important as it now provides us with the tools to examine the effects of age on the release of nitric oxide from key neurones in the feeding circuit.
Bhavik Anil Patel, Martin Arundell, Kim H. Parker, Mark S. Yeoman and Danny O’Hare. Detection of nitric oxide relezzase from single neurons in the pond snail, Lymnaea stagnalis. Anal Chem. 2006, 78(22):7643-8).
A neuron may generate several different neurotransmitter signals simultaneously
We have developed a new method, based on the Hilbert transform, which greatly improves our ability to measure the effects of more than one transmitter simultaneously. (Costas A. Anastassiou, Bhavik A. Patel, Martin Arundell, Mark S. Yeoman§ Kim H. Parker and Danny O’Hare. Novel subsecond voltametric separation between dopamine and serotonin in the presence of ascorbate. Anal. Chem. 2006, 78(19)6990-8.
Our group is the first to quantify dopamine and serotonin concentrations simultaneously using electrochemistry and the Hilbert transform. Dopamine (DA) and serotonin (5-HT) are key neurotransmitters in the CNS that regulate feeding in the pond snail Lymnaea and are important in regulating feeding in higher organisms. The development of this algorithm to allow the simultaneous quantification of 5-HT and DA will provide a significant step forward in understanding how these two important neurotransmitters interact to control motor behaviours and how their function changes with age.
