The physiological properties of amine‐containing neurones in the lobster nervous system.

Abstract

SUMMARY1. Our previous studies have shown that octopamine and serotonin are found associated with a system of neurones in the connective tissue sheath of the second roots of lobster thoracic ganglia. To try to understand the mechanism of activation of these neurones, we undertook an examination of their general physiological properties.2. All of the neurones receive excitatory synaptic input that has a cholinergic pharmacology, which suggests that it may be from sensory neurones. A very limited number of cells, possibly one, provides the total synaptic input to all the cells in the roots of the second and third thoracic segments.3. The cells within one root are electronically coupled to each other. The extent of coupling varies widely between cells; on occasion the coupling is sufficiently tight for action potentials originating in one cell to trigger action potentials in the neighbouring cell.4. The majority of the cells show no spontaneous activity at temperatures below 14 0C, but become spontaneously active above that temperature. Cells cycle reversibly from silent to continuously active to bursting and back as the temperature is increased and decreased.5. Octopamine and serotonin both inhibit the bursting activity. The octopamine response is blocked by phentolamine but not by propranolol, while the inhibitory action of serotonin is unaffected by either of these drugs. The amine-inhibition of the firing could be an autoregulatory mechanism for cell activity.6. The physiological properties described in this paper suggest that the widely dispersed amine-containing neurones in lobsters behave like a neurosecretory organ in terms of their mechanism of activation.

Effect of acute temperature change on lung respiration of the mollusc Lymnaea stagnalis

“…This does not suffocate the animal taking into consideration the absence of lung ventilation via the decreased oxygen requirements at lower water temperatures. The similar blockade of spontaneous neuronal activity during temperature decreases has been reported in various invertebrates including Limax feeding neurons (Prior and Grega, 1982) and lobster neurons (Konishi and Kravitz, 1978).…”

Cloning and distribution of a putative octopamine/tyramine receptor in the central nervous system of the freshwater prawn Macrobrachium rosenbergii

“…Specific receptors for OA have been identified through the use of pharmacological and biochemical assays in many invertebrate phyla, including arthropods and mollusks (Axelrod and Saavedra, 1977; Harmer and Horn, 1977; Konishi and Kravitz, 1978; Battelle and Kravitz, 1978; Nathanson, 1979; Battelle et al, 1979; Kravitz et al, 1980; Evans, 1981; Harris-Warrick and Kravitz, 1984). In addition, pharmacological studies in insects have provided evidence for the existence of multiple subtypes of OA receptors (Evans 1980, 1981, 1987; Evans et al, 1988).…”

Temperature dependent modulation of lobster neuromuscular properties by serotonin

“…For example, thermal change alters the firing rate of specific lobster neurons (Konishi and Kravitz, 1978), the release of hormones from lobster neurosecretory organs (Kuramoto and Tani, 1994), the strength of long-term facilitation at crayfish neuromuscular synapses (Jacobs and Atwood, 1981a;Jacobs and Atwood, 1981b), the physiological properties of crayfish gap junctional synapses (Heitler and Edwards, 1998), and the conduction velocity of action potentials in crabs (Young et al, 2006).…”