Em Tansey

The effects of some anaesthetic agents in Octopus vulgaris

Abstract 1. The effects of anaesthesia induced by immersion in urethane (3%), ethanol (2%) or seawater at 4°C were compared in Octopus vulgaris. 2. Immersion in urethane or ethanol appeared to traumatise the animals; the majority began to climb out within 30 seconds of immersion. This was not observed with cold water. All three substances induced “anaesthesia” in 2–5 min. 3. Immersion in cold water produced a typical flashing chromatophore display not seen with either of the other procedures. 4. A period of hyperventilation was observed during recovery from all three anaesthetics. Recovery of respiration, chromatophore activity and posture always occurred in that sequence irrespective of anaesthetic. 5. The criteria for assessing general anaesthesia in Octopus vulgaris are discussed.

Neurotransmitters in the cephalopod brain

Abstract 1. 1.The presence of possible neurotransmitter substances in the central nervous systems of cephalopod molluscs is reviewed. 2. 2.The evidence suggests that acetylcholine; The catecholamines dopamine and noradrenaline; and 5-hydroxytryptamine are possible neurotransmitters. 3. 3.The evidence is less good for other amines or amino acids having a similar role.

THE DIGESTIVE-TRACT OF OCTOPUS-VULGARIS - THE ANATOMY, PHYSIOLOGY AND PHARMACOLOGY OF THE UPPER TRACT

This paper reports a preliminary investigation into physiological and pharmacological aspects of the motor activity of the digestive tract of Octopus vulgaris, with reference tothe relevant anatomy. The results suggest that the octopus gut shows many similarities to somevertebrate guts in terms of functional morphology and motor control. Pharmacological experiments suggest that acetylcholine, noradrenaline and 5HT may act as neurotransmitters and probablyregulate the digestive activity by antagonistic actions, reminiscent of the classical divisions of the vertebrate autonomic nervous system. Histochemical evidence is presented that some ofthese substances are located in the nerves and ganglia of the digestive tract.

THE CHROMATIC AND MOTOR EFFECTS OF NEUROTRANSMITTER INJECTION IN INTACT AND BRAIN-LESIONED OCTOPUS

Various neurotransmitters were injected into the blood supplying the brain of Octopus vulgaris and the effects, particularly on the chromatophores, were observed. l -glutamate, GABA, dopamine, noradrenaline and octopamine caused expansion of the chromatophores and darkening of the skin; ACh caused retraction of the chromatophores and paling; 5HT caused differential expansion and retraction: mottling. These responses, which are neurally mediated, were particularly well defined for ACh and 5HT and the effects of these drugs were studied in more detail. The paling effect of ACh was mimicked by nicotine but not muscarine and was partially antagonized by tubocurarine. The mottling induced by 5HT was transiently antagonized by methysergide maleate, as was ink-ejection and defaecation. Brain lesions to localize the sites of action of ACh and 5HT suggest that they act at the level of the sub-oesophageal lobes to control the chromatophores, but that 5 HT may act at the level of the optic lobe to control inking and defaecation. These results are related to the pharmacology and histochemistry of the cephalopod brain and to the organization of the chromatophore control system.

Colour Changes in Cephalopods after Neurotransmitter Injection into the Cephalic Aorta

A method by which small quantities (1–10 μg) of neurotransmitters can be injected into the blood supplying the brain of cephalopods has been used to produce conspicuous and instantaneous colour changes in the skin of the arms, head and body. Of the transmitter substances known to be present in the cephalopod brain, dopamine, noradrenalin and octopamine cause darkening when injected, acetylcholine causes paling and 5- hydroxytryptamine elicits a mottled patterning. Other evidence is presented that these substances are acting centrally to produce these effects, and the findings are related to the known organization of the lobes in the c. n. s. controlling the chromatophores.

Not Committing Barbarisms: Sherrington and the Synapse, 1897

The word synapse first appeared in 1897, in the seventh edition of Michael Fosters Textbook of Physiology. Foster was assisted in writing the volume on the nervous system by Charles Sherrington, who can be credited with developing and advocating the physiological concept of a synapse. The word itself however, was derived by a Cambridge classicist, Arthur Verrall.

Aminergic innervation of the blood vessels of Octopus vulgaris

SummaryEvidence is presented from fluorescence histochemistry studies that blood vessels in the viscera of Octopus vulgaris are innervated by nerve fibres containing catecholamines. This, with other evidence, suggests that cephalopods, like vertebrates, may be capable of regulating their peripheral vasculature by central neural control.

Chemical neurotransmission in the autonomic nervous system: Sir Henry Dale and acetylcholine.

The concept of chemical neurotransmission arose from detailed studies on the functioning of the autonomic nervous system, particularly those of T. R. Elliott, H. H. Dale and Otto Loewi during the first three decades of the 20th century. This paper will assess some of their contributions, and discuss the relevance of earlier work, especially that of W. H. Gaskell and J. N. Langley, on the anatomy and physiology of the autonomic nervous system. Emphasis is given to the work that Dale and his colleagues performed on the elucidation of acetylcholine as a normal constituent of the mammalian body, and subsequently as a probable chemical neurotransmitter in the parasympathetic nervous system, at other autonomic sites and at the voluntary neuromuscular junction.

The relationship between axonal transport of protein and demyelination in the optic nerves of mice infected with Semliki Forest Virus

Abstract Fast and slow axonal transport of protein have been studied in the optic nerves of mice infected with Semliki Forest Virus (SFV) that causes patchy demyelination throughout the CNS. Intravitreal injections of [3H]proline were given at regular intervals after virus inoculation, the labelled protein in the superior colliculi was then measured after survival periods of 18 h or 10 days, for fast and slow axonal transport studies, respectively. Fast transport studies showed an enhanced amount of protein arriving at the optic nerve terminals (superior colliculus) of the SFV-infected mice prior to the onset of demyelination. In contrast, the slow transport studies showed an enhanced amount of protein at the superior colliculus of the SFV-infected mice during the demyelination period. There was no concomitant increase in labelled protein in the retina at any time after the SFV infection. It is proposed that alteration in the transport of the protein constituents other than major myelin specific components may cause disruption of myelin maintenance in SFV infection.

A TECHNIQUE FOR CENTRAL DRUG ADMINISTRATION IN OCTOPUS-VULGARIS

Abstract A technique is described for non-chemical anaesthesia and for the surgical implantation of a cannula system for the injection of drugs into the central nervous system of Octopus vulgaris.