Effects of prolactin on chloride cells in opercular membrane of seawater-adapted tilapia.
Effects of prolactin on morphology and numbers of chloride cells in the opercular membrane of seawater-adapted tilapia (Oreochromis mossambicus) have been examined. Following five daily injections of ovine prolactin at a dose of 10 micrograms.g body wt-1, blood samples were taken and opercular membranes were removed and stained with a fluorescent mitochondrial dye (dimethylaminostyrylethylpyridiniumiodine), a fluorescent derivative of ouabain (anthroylouabain), and a histological stain specific for the extensive tubular system of chloride cells (zinc-osmium-iodine). Mean plasma osmolarity and sodium increased 23-24% following prolactin injection. An increase in the relative frequency of chloride cells between 20 and 180 microns2 in cross-sectional area and a decrease in the relative frequency of chloride cells greater than 180 microns2 were observed following prolactin injections. Average cell size decreased 46-70% and cell height decreased 26-38% following prolactin injections. There was no significant change in cell density. Anthroylouabain staining was observed in both prolactin- and saline-injected fish, and no significant effect on Na+,K(+)-adenosinetriphosphatase activity was seen in either opercular membrane or gill tissue. The results demonstrate an effect of prolactin on chloride cell size and provide a morphological correlate for decreased secretory activity of chloride cells following prolactin injections.
Herndon
T M
TM
Department of Integrative Biology, University of California, Berkeley 94720.
McCormick
S D
SD
Bern
H A
HA
D000064:Acclimatization; D000818:Animals; D002712:Chlorides / Q000378:metabolism*; D005399:Fishes / Q000502:physiology*; D005618:Fresh Water; D005880:Gills / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D008566:Membranes / Q000187:drug effects / Q000502:physiology; D009994:Osmolar Concentration; D011388:Prolactin / Q000494:pharmacology*; D012016:Reference Values; D012623:Seawater; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D002712:Chlorides; D011388:Prolactin; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase