L D Leake

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A pair of giant Retzius (R) cells in each segmental ganglion of the leech contain 5-hydroxytryptamine (5-HT). They are the only 5-HT-containing neurones in the central nervous system to send branches to the periphery, yet many peripheral tissues (e.g. body wall muscles, heart, reproductive organs, nephridia and gut) possess 5-HT-like immunoreactive nerve(More)
The presence and distribution of putative nitric oxide synthase (NOS)-containing cells in whole-mount preparations of the central nervous system of the leech, Hirudo medicinalis, were studied using NADPH-diaphorase (NADPH-d) histochemistry. Specific staining occurred mainly in somata of some central neurones but NADPH-d-reactive branches and terminals were(More)
1. Leech Retzius (R) neurons are excited by carbachol, and this action is blocked by benzoquinonium (Mytolon). 2. Pyrethroids induce spontaneous depolarizations in R neurons. These events are not blocked by benzoquinomium, therefore pyrethroids are not acting on the cholinoreceptor. 3. A congeneric series of synthetic pyrethroids, the QSAR compounds, also(More)
1. 5-Hydroxytryptamine (5-HT) receptors in the Retzius neurones (R cells) and longitudinal body wall muscle strips of the leech H. medicinalis were studied using a range of selective agonists developed for mammalian receptors. 2. All agonists induced hyperpolarisation of R cells: the order of their potency was 5-HT > 5-CT > 2-Me 5HT > alpha-Me-5-HT > >(More)
An hypothesis for the presence of nitric oxide synthase (NOS) and the involvement of nitric oxide (NO) in neuronal signaling in the leach (Hirudo medicinalis) CNS is based on (i) the presence of fixative resistant NADPH-diaphorase (NADPH-d) in a specific neuronal population in the segmental ganglion; (ii) direct measurements with NO-sensitive electrodes(More)
1. Changes in the activity pattern of leech Retzius (R) cells were investigated using intracellular recording. 2. The presence of an after-hyperpolarisation (AHP) is closely related to activity pattern; regular firing being associated with an AHP, bursting with its absence. 3. Increasing external calcium (Cao), cyclic AMP levels or activity of kinase A(More)
1. Reserpine, chronic guanethidine denervation and alpha-adrenoceptor antagonists were used to distinguish between presynaptic and postsynaptic actions of exogenous dopamine (DA), octopamine (OA), tyramine (TA) and noradrenaline (NA) on the rat vas deferens. 2. TA has only a presynaptic action while DA and OA have mixed presynaptic actions (releasing(More)
1. Exogenous dopamine (DA), octopamine (OA), noradrenaline (NA), and the alpha 1-agonist methoxamine (MX), all induce tonic and rhythmic contractions in the rat vas deferens. 2. Tonic and rhythmic contractions can be separated by use of different concentrations of alpha 1-adrenoceptor antagonists, verapamil, pyrogallol (a COMT-inhibitor) and lowering bath(More)
Octopamine (OA) hyperpolarizes leech Leydig neurones but response amplitudes and thresholds vary. Associations between response, OA dose and other variables [initial resting potential, action potential (AP) frequency and amplitude, temperature, microelectrode resistance, position of ganglion along nerve cord, animal, treatment order] were examined using(More)