Grace E. Pickford

Prolactin, a Factor in Promoting Survival of Hypophysectomized Killifish in Fresh Water

The naturally occurring corticosteroids, cortisol and aldosterone, failed to promote survival of hypophysectomized Fundulus heteroclitus in fresh water. Extracts of Fundulus interrenal tissue, carp corpuscles of Stannius, and hog renin were ineffective. Injection of whole rat-pituitary brei was partially successful. Highly purified prolactin maintained survival, although the recipients did not eat normally. A synergic action of prolactin with some unidentified pituitary hormone is suspected.

Sodium- and potassium-activated adenosine triphosphatase of gills: role in adaptation of teleosts to salt water.

The activity of adenosine triphosphatase activated by sodium and potassium ions is greatly increased in the gill and pseudobranch of the euryhaline killifish, Fundulus heteroclitus, after its adaptation to seawater. Adenosine triphosphatase activity in gills of fish in salt water is reduced by hypophysectomy. The data suggest that this enzyme is involved in the excretion of sodiumions by the gill and that the adaptive increase which occurs in seawater is influenced by the hypophysis.

Hypophysectomy, replacement therapy, and the tolerance of the euryhaline killifish, Fundulus heteroclitus, to hypotonic media

Abstract Hypophysectomized Fundulus heteroclitus, as previously reported, survive only a few days after transfer from salt to fresh water. Survival time is the same when fish are tested 2 weeks or 2 months after hypophysectomy. Gradual dilution of the external medium produces failure at an average salinity of 0.26% (0.67-0.02%). This salinity is comparable to that causing failure after abrupt transfer. Although failure is associated with hypochloremia, daily inlections of a balanced salt solution or 0.6% NaCl shorten survival. Daily injections of teleostean neurohypophysial peptides, arginine vasotocin (2.25 and 0.0225 pressor mU per gram) and isotocin (1.32 and 0.026 oxytocic mU per gram) do not prolong survival. An extract of candal neurosecretory tissue (urophysis) from male Tilapia mossambica had no beneficial action at doses of 50 μg per gram every other day. Purified ovine prolactin, 105 mU per gram on alternate days, maintained survival of 10 of 11 fish for the duration of the 28-day test period in fresh water, irrespective of the period of pretreatment is salt water. Purified bovine prolactin prolonged survival and 2 of 6 fish were maintained for 28 days. Purified bovine growth hormone was ineffective. Monkey growth hormone containing 2 U per milligram of prolactin activity, administered at a dose of 20 μg per gram (equivalent to 40 mU per gram prolactin activity), prolonged survival. Human growth hormone containing 4 U per milligram of prolactin activity, at a dose of 20 μg per gram (equivalent to 80 mU per gram prolactin activity) also prolonged survival and 4 of 6 fish were maintained for 28 days. The ability of pituitary preparations to protect hypophysectomized F. heteroclitus from failure in fresh water appears to be related to their prolactin activity and not to their content of neurohypophysial peptides. This suggests that an adenohypophysial hormone resembling mammalian prolactin is essential for survival of this fish in hypotonic external media. Carp pituitary preparations do not protect hypophysectomized F. heteroclitus although F. heteroclitus pituitaries are known to be effective.

The response of the hypophysectomized cyprinodont, Fundulus heteroclitus, to replacement therapy with cortisol: Effects on blood serum and sodium-potassium activated adenosine triphosphatase in the gills, kidney, and intestinal mucosa

Regulation of the inorganic constituents of the serum is nearly perfect in hypophysectomized Fundulus heteroclitus maintained in salt water, although serum Cl is lower. Chronic treatment with cortisol had no effect on serum Na or serum Ca; serum K and serum Cl decreased, serum inorganic PO4 and serum Mg increased. Na + K-ATPase activity increased in cortisol-treated fish in three organs that participate in osmoregulation: the gills, the kidneys (males only), and the intestinal mucosa. The increase in the gills can be correlated with a restoration of total Na exchange, previously reported by Mayer and Maetz (1967). The increased activity in the intestine, previously reported by Hirano et al. (1967) in Anguilla japonica, is presumably associated with the increased rate of Na turnover. Increased activity in the kidneys may reflect an increase in the glomerular filtration rate and (or) a restoration of renal Na retention. Other effects of cortisol are: a decrease in body weight, an increase in the abundance of circulating erythrocytes, leukocytosis after a single injection or short treatment that is regulated after longer treatment, and an increase in the relative weight of the liver that may be associated with gluconeogenesis. Cortisol had no effect on the relative size of the regressed gonads in either sex.

Effects of methyl testosterone on the testes of a hypophysectomized cyprinodont fish, Fundulus heteroclitus ☆

Administration of methyl testosterone to hypophysectomized, sexually regressed, male Fundulus heteroclitus (2 μg/gm, thrice weekly) initiated the development of nuptial coloration within two weeks. Stimulation of spermatogenesis was evident after 4 weeks, and at 8 weeks free spermatozoa were present in the efferent ducts of 4 out of 6 fish. Although the gonadosomatic index was significantly increased, testis size was one-tenth that of intact males in the breeding season. Eight-week treatment also caused hypertrophy of the epithelium of the efferent ducts and restored the atrophied interstitial cells to near normal breeding condition. A lower dose of methyl testosterone (0.2 μg/gm) for 8 weeks caused essentially similar changes in the testes, but the development of nuptial coloration (attributed to direct action of the androgen) proceeded more slowly.

Seasonal variations in the hormone content of the pituitary gland of the perch, Perca fluviatilis L

Abstract Lyophilized pituitary brei of Perca fluviatilis , taken from Windermere at seasonal intervals, was administered to hypophysectomized male Fundulus heteroclitus by intraperitoneal injection, thrice weekly for 6 weeks, at 100 μg in 0.01 ml of 0.6% NaCl per gram weight of fish. Two control groups received 0.6% NaCl and standard beef growth hormone (NIH-GH-Bi, 20 μg/gm), respectively. Stimulation of growth in length, supplemented by parallel data on weight and scale-width increments, was equivalent to 20–50 μg GH-B6 during the autumn and winter months. A significant increase in growth-promoting potency in April was followed by a maximum in June, equivalent to 250 μg of GH-B1. A decline in July was followed by near total exhaustion of the growth-promoting potency of the perch pituitary in August. The maximum accumulation of growth hormone in the hypophysis preceded the estimated natural growth peak of the perch by 4–6 weeks. No such lag was observed in respect to the gonads: maximal gonadotrophin content of the hypophysis, reflected in stimulation of regressed testes and onset of nuptial coloration in the assay fish, coincided with the peak of the natural reproductive cycle in April. In August the pituitary was depleted of gonadotrophin. The thyrotrophic activity of the perch pituitary followed a similar cycle, of lesser magnitude. Perch pituitary preparations maintained adrenal cortical histology at near normal, except in July; and stimulated the restoration of melanin pigment, proliferation of new melanocytes, and the spawning reflex response.

SERUM COMPOSITION OF FRESHWATER STRINGRAYS (POTAMOTRYGONIDAE) ADAPTED TO FRESH AND DILUTE SEA WATER

1. Juvenile freshwater stingrays of the family Potamotrygonidae are unable to survive in salinities in excess of 20.6‰ when gradually acclimated.2. No differences were observed in blood pH or hematological parameters when fish adapted to a salinity of 14.5‰ were compared with freshwater controls.3. Significant increases were found in serum sodium (21%), chloride (21%), calcium (48%), and magnesium (51%). Increases in total CO2 (16%), potassium (21%), and inorganic phosphorus (35%) were not significant on account of high variance. Serum osmolarity increased 69%.4. There was no apparent effect of salinity on serum total cholesterol, organically bound phosphorus, or total carbohydrates. Glucose contributed only 25% of the latter.5. Serum urea was low (1.1 mM/1) as previously reported, and the trend to increase in a saline environment was not osmotically significant.6. Freshwater stingrays are unique among elasmobranchs in possessing significant amounts of a protein with the electrophoretic mobility of human ...

Serum Osmolality in the Coelacanth, Latimeria chalumnae: Urea Retention and Ion Regulation

Samples of blood (hemolyzed) were obtained from the renal vein, the hepatic portal vein, and the heart of a freshly thawed specimen of Latimeria chalumnae. The coelacanth uses high concentrations of urea to maintain its serum osmolality at approximately that of sea water. The mean value for the total osmolality was 1181 milliosmoles per liter. The mean values (milliequivalents per liter) were: for sodium, 181; for potassium, 51.3; for calcium, 6.9; for magnesium, 28.7; for chloride, 199; and for bicarbonate, 4.7. The mean urea concentration was 355 millimoles per liter, and the mean nonprotein nitrogen was 1343 milligrams percent. Heart blood showed significantly lower values for osmolality (921 milliosmoles per liter) and nonprotein nitrogen (1030 mg percent) and was probably less severely contaminated with products of protein breakdown. Fluid from the anterior chamber of the eye showed values of 952 milliosmole/liter; the urea value for this fluid was 303 mmole/liter, and the magnesium was 7.3 meq/liter. The magnesium value for the aqueous humor was used to correct the abnormally high concentrations in the hemolyzed serum. The high level of serum potassium also was attributed to hemolysis.

Hypocalcemia and tetanic seizures in hypophysectomized killifish, Fundulus heteroclitus.

Summary Tetanic convulsions were observed in hypophysectomized Fundulus heteroclitus kept in calcium deficient but hyperosmotic conditions. Analysis of sera revealed a large decrease in total calcium and inorganic phosphate although sodium, potassium, and chloride were unaffected. These defects in calcium metabolism were corrected by returning the tetanic fish to a calcium-rich environment.

Failure of hog thyrocalcitonin to elicit hypocalcemia in the teleost fish, Fundulus heteroclitus

Abstract 1. 1. Hog thyrocalcitonin was administered to three physiologically different groups of male Fundulus heteroclitus at a dose of 0·2 mg (2–4 units) per g wt. of fish. Group 1 were intact fish maintained in salt water and fed; Group 2 were intact fish adapted to fresh water (low clacium) and starved for the final week; Group 3 were hypophysectomized fish maintained in salt water, and fed. 2. 2. Within each group there were no significant differences in serum-soluble calcium between controls and hormone-treated fish. 3. 3. Neither the time to autopsy (1–4 hr) nor the site of the injection (intraperitoneal or intravenous) had any effect. 4. 4. Differences between the three groups could be related to the state of maturation of the testes.