Nervous Control of Stomach Movements in Dogfishes and Rays

Abstract

The organization of the alimentary canal of fishes differs greatly between species of different dietary habit, but is not well understood. The vagus and sympathetic systems are very different in elasmobranchs and teleosts, but there has been little work on the corresponding physiology and pharmacology. The digestive system of elasmobranchs has unusual features connected with the fact that the absorbtive surface is provided by the spiral intestine (Fig. 1). This is a short fat tube whose surface is greatly increased by the presence of a coiled fold, the spiral valve. This arrangement provides a large area for absorbtion, neatly packed, but it leaves only a narrow lumen, so that no large particles can pass along the spiral intestine. Presumably it is in connexion with this condition that the stomach is divided into two parts. The cardiac division is a large sac into which the prey is received whole, its wall is very glandular and much breakdown of the food proceeds there (Hogben, 1967). The pyloric division is a narrower tube, leading from the hind end of the cardiac part to the pylorus.

5‐Hydroxytryptamine is a possible neurotransmitter of the non‐cholinergic excitatory nerves in the longitudinal muscle of rainbow trout stomach (Salmo gairdneri)

“…Non-cholinergic excitatory innervation has been found in some species of fish, such as goldfish (Burnstock et al, 1972), dogfish (Nilsson & Holmgren, 1983), rainbow trout (Campbell & Gannon, 1976;Holmgren & Nilsson, 1981), ray (Young, 1980a), angler (Young, 1980b) and carp (Kitazawa et al, 1988). On the basis of the similarity of the contractile responses to non-cholinergic nerve stimulation and contractile agents, ATP (Burnstock et al, 1972;Young, 1980b), catecholamines (Campbell & Gannon, 1976;Nilsson & Holmgren, 1983), 5-hydroxytryptamine (5-HT) (Young, 1980a) and substance P (Kitazawa et al, 1988) were considered as possible neurotransmitters of the non-cholinergic excitatory nerves in fish.…”

“…On the basis of the similarity of the contractile responses to non-cholinergic nerve stimulation and contractile agents, ATP (Burnstock et al, 1972;Young, 1980b), catecholamines (Campbell & Gannon, 1976;Nilsson & Holmgren, 1983), 5-hydroxytryptamine (5-HT) (Young, 1980a) and substance P (Kitazawa et al, 1988) were considered as possible neurotransmitters of the non-cholinergic excitatory nerves in fish.…”

Control of movements of the stomach and spiral intestine of Raja and Scyliorhinus

“…Some description was given recently of the stomach of the dogfish and skate (Young, 1980). Some description was given recently of the stomach of the dogfish and skate (Young, 1980).…”

“…Investigation of movements of the whole spiral intestine has been attempted by attaching hooks to it and stimulating the sympathetic supply by the method already described (Young, 1980). In Scyliorhinus the movements were mostly too slight and irregular to be recorded in this way.…”

“…Some description was given recently of the stomach of the dogfish and skate (Young, 1980). By contrast the nerves of the spiral intestine are excitatory.…”