2. THE NEUROHYPOPHYSIS
191
it may be present in trace quantities in cartilaginous fish, its constant
presence is a remarkable example of evolutionary stability. By contrast,
the neutral neurohypophysial peptides show more variation (Fig. 12).
They may be absent in the cyclostomes, although this is not well established. The elasmobranchs may contain 4 Ser, 8 Gln oxytocin and other
unknown principles, but the bony fish appear to utilize 4 Ser, 8 Ile oxytocin. The lungfish contain 8 Ile oxytocin, and perhaps oxytocin, and are
effectively amphibians in terms of their neurohypophysial principles.
Although there have been clear advances in the study of the morphology of the fish pituitary, and the nature of the neurohypophysial
principles is becoming better established, there is more confusion and
uncertainty with regard to the actions and functions of the hormones in
fish metabolism. At present there are strong suggestions that the neurohypophysial peptides are concerned in salt and water balance, most
particularly on sodium metabolism. The loss of water by the kidney may
be controlled by effects on glomerular filtration rate, perhaps through
actions on the circulatory system. There are suggestions that the neurohypophysial peptides might be important in reproduction and influence
spawning and egg laying. It is possible that the basic principles are more
important in osmoregulation and salt balance, while the neutral peptides
find a function in reproduction: This would parallel the situation in the
mammal, but at the present time this is almost pure speculation. Although a basic pattern of function may emerge, the marked differences
between the metabolism of such diverse fish as elasmobranchs and teleosts
may well imply that neurohypophysial principles have widely different
uses in different fish.
REFERENCES
Acher, R., Chauvet, J., and Chauvet, M. T. (1967). Phylogeny of the neurohypophysial hormones. Nature 216,1037-1038.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1961). Les hormones neurohypophysaires des poissons. Isolement d'une vasotocine du tacaud (Gadus Zzlscus.
L. ). Biochim. Biophys. Actu 51,419420.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1962). Isolement d'une
nouvelle hormone neurohypophysaire, l'isotocine, prhsente chez les poissons
osseu. Biochim. Bwphys. Actu 58,624-625.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1965a). Phylogknie des
peptides neurohypophysaires : Isolement d'une nouvelle hormone, la glumitocine
(Ser 4Gln 8-ocytocine) prbsente chez un Poisson cartilagineux, la raie (Raiu
clauutu). Biochim. Biophys. Actu 107, 393396.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1965b). Les hormones neurohypophysaires des vertbbres. Variations des structures au cours de l'bvolution.
Ann. Endocdnol. (Paris) 26,662-669.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1965~). Characthrisation des
191
it may be present in trace quantities in cartilaginous fish, its constant
presence is a remarkable example of evolutionary stability. By contrast,
the neutral neurohypophysial peptides show more variation (Fig. 12).
They may be absent in the cyclostomes, although this is not well established. The elasmobranchs may contain 4 Ser, 8 Gln oxytocin and other
unknown principles, but the bony fish appear to utilize 4 Ser, 8 Ile oxytocin. The lungfish contain 8 Ile oxytocin, and perhaps oxytocin, and are
effectively amphibians in terms of their neurohypophysial principles.
Although there have been clear advances in the study of the morphology of the fish pituitary, and the nature of the neurohypophysial
principles is becoming better established, there is more confusion and
uncertainty with regard to the actions and functions of the hormones in
fish metabolism. At present there are strong suggestions that the neurohypophysial peptides are concerned in salt and water balance, most
particularly on sodium metabolism. The loss of water by the kidney may
be controlled by effects on glomerular filtration rate, perhaps through
actions on the circulatory system. There are suggestions that the neurohypophysial peptides might be important in reproduction and influence
spawning and egg laying. It is possible that the basic principles are more
important in osmoregulation and salt balance, while the neutral peptides
find a function in reproduction: This would parallel the situation in the
mammal, but at the present time this is almost pure speculation. Although a basic pattern of function may emerge, the marked differences
between the metabolism of such diverse fish as elasmobranchs and teleosts
may well imply that neurohypophysial principles have widely different
uses in different fish.
REFERENCES
Acher, R., Chauvet, J., and Chauvet, M. T. (1967). Phylogeny of the neurohypophysial hormones. Nature 216,1037-1038.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1961). Les hormones neurohypophysaires des poissons. Isolement d'une vasotocine du tacaud (Gadus Zzlscus.
L. ). Biochim. Biophys. Actu 51,419420.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1962). Isolement d'une
nouvelle hormone neurohypophysaire, l'isotocine, prhsente chez les poissons
osseu. Biochim. Bwphys. Actu 58,624-625.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1965a). Phylogknie des
peptides neurohypophysaires : Isolement d'une nouvelle hormone, la glumitocine
(Ser 4Gln 8-ocytocine) prbsente chez un Poisson cartilagineux, la raie (Raiu
clauutu). Biochim. Biophys. Actu 107, 393396.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1965b). Les hormones neurohypophysaires des vertbbres. Variations des structures au cours de l'bvolution.
Ann. Endocdnol. (Paris) 26,662-669.
Acher, R., Chauvet, J., Chauvet, M. T., and Crepy, D. (1965~). Characthrisation des