Involvement of pituitary-interrenal axis and cholinergic mechanisms during the cold-shock leucocyte sequence in a fresh water tropical teleost, Colisa fasciatus
Srivastava, A.K.; Agrawal, U.
Archives d'Anatomie Microscopique et de Morphologie Experimentale 66(2): 97-108
1977
ISSN/ISBN: 0003-9594 PMID: 603239 Document Number: 118049
Immersion of Colisa fasciatus in ice water for 90 s elicited significant changes in the abundance of circulating leukocytes at selected time intervals (3, 15 and 27 min, at intervals of 48 min up to 363 min and at 12 and 24 h) post cold-shock. Leukocytosis erupted at 15 through 123 min and at 267 min; leukocyte counts at 3, 171-219 and 363 min and at 12 and 24 h were comparable to those of the unshocked fish. I.p. injections of cortisol (2.5 .mu.g/g) elicited leukocytosis at 27 min and leukopenia at 315 and 363 min following administration of the hormone to the fish; at other time periods the leukocyte counts for the experimentals and controls were not significantly different. Pretreatment of the fish with metopirone (400 .mu.g), an adrenocortical inhibitor, for 3 days abolished the cold-shock leukocytic (15 through 123 min and 267 min) as well as cortisol-elicited leukopenic (315 and 363 min) phases. Injections of acetylcholine (300 .mu.g) elicited leukocytosis at 27 min and at 3 and 171 min. Injections of atropine (300 .mu.g) followed by cold-shock prevented the acetylcholine-induced leukocytic phases but leukopenic phases at 315 and 363 min were not abolished. Pretreatment with phenoxybenzamine abolished the leukocytic phases except at 27 min. The typical leukocyte sequence observed after cold-shock or after treatment with any of the 4 drugs did not elicit corresponding changes in the abundance of erythrocytes or thrombocytes. The involvement of both adrenergic and cholinergic mechanisms as well as the pituitary-interrenal axis during the leukocyte stress syndrome was discussed.