SUMMARY1. Growing male domestic fowl of an egg-laying strain were fed ad libitum and injected intraperitoneally with melatonin or intramuscularly with triiodothyronine (T3) to study the effects on sleep, food intake, blood glucose, e.e.g., oxygen consumption and carbon dioxide production.2. Melatonin caused a dose-related depression of food intake with sleep and aphagia lasting for 21 hr following 8 mg, drowsiness and greatly reduced intake following 4 and 2 mg and a slight reduction in food intake after 1 mg.3. T3 injection was followed by increased feeding within the range 50-200 jug. The higher dose (200 jug) completely prevented the effects of 10 mg melatonin injected simultaneously.4. Melatonin (10 mg) depressed plasma glucose levels whereas T3 (200 ,sg) elevated blood glucose.5. Either darkness or melatonin (10 mg) caused an increase in amplitude and a decrease in frequency of the e.e.g. 6. Birds fasted for 3 hr before injection showed significantly lower oxygen consumption and carbon dioxide production when given melatonin (10 mg); T3 had no effect within the 4 hr period after injection and did not modify the effects of melatonin.7. It is postulated that the rapid effects of melatonin and T3 which were observed result from direct effects of these hormones on the central nervous system.
Cyproheptadine stimulates food intake and growth in some species of mammal; its effects are reported here in chickens. Growing cockerels of an egg-laying strain were given 0.32 mg/d by mouth, which resulted in significant increases in weight gain and food intake, including feeding during the night. Increasing daily doses of up to 1.6 mg/kg body weight stimulated intake in a dose-related manner, while 1.92 mg/kg had the same effect as 0.96 mg/kg. Neither pinealectomy, which is known to stimulate food intake, nor treatment with melatonin, which depresses intake, interacted with the effects of cyproheptadine on food intake, showing that its effect is not mediated by the pineal gland.
The effect of feeding adult Swiss albino mice of both sexes a diet supplemented with 0, 125, 250 and 500 parts/106 of fluoride for four and eight week periods on haemoglobin concentration (Hb), packed cell volume (PCV) and mean corpuscular haemoglobin concentration (MCHC) was investigated. Values of the three parameters were significantly lowered at both periods in the treated groups as compared with the controls. The extent of reduction in these values was, in general, dependent on the dose of supplemented dietary fluoride. Clinical symptoms were not observed before the end of the sixth week. However, appearance of the symptoms did not change the trend of variations in Hb, PCV and MCHC values. The reduced values could be the result of lowered haemoglobin synthesis and erythropoiesis. It was suggested that these haematological indices could serve to detect preclinical effects of high fluoride intake with an added dose of as low as 125 parts/106, or even less, for a period of four weeks or probably earlier.There have been many studies of the adverse effects of high fluoride intake on bones and teeth of man and animals [Velu, 1932;MacIntire, Winterberg, Clements and Dunham, 1947; Neeley and Harbaugh, 1954;Merriman, Moorman and Hobbs, 1956;Brown, Christofferson, Massler and Weiss, 1960;Johnson, 1965;Shupe, 1969;Bhussry, 1970;McClure, 1970;Jones, 1972;Rosenquist and Lemperg, 1974;Yamamoto, Wergedal and Baylink, 1974;Gileva, Plotko and Gatiyatullina, 1975;Lough, Noonan, Gagnon and Kayne, 1975]. Other tissues, however, as possible affected sites have received less attention. Research reports describing the effects of high levels of fluoride on the blood picture and haematopoietic system are not so frequently encountered.Hoogstratten, Leone, Shupe, Greenwood and Liberman [1965] reported an increase in blood and bone marrow eosinophils and a decrease in serum folic acid activity of cattle received a fluoride-supplemented ration for a period of seven and a half years. The daily ingested level of fluoride was 93 parts/106.Decreased blood levels of copper and calcium, as well as lowered values of packed cell volume (PCV), were observed in sheep grazing, for not less than two years, on pasture contaminated with rock phosphate dust containing 2-1-3-3 % of fluoride emitted from a fertilizer factory [Zumpt, 1975]. The concentration of fluoride in the grazed forage, on a dry matter basis, was 232 parts/106. The effect of a high level of fluoride on some haematological aspects of the rat was investigated by Kahl, Wojcik and Ewy [1973]. Sodium fluoride at a concentration of 150 parts/106 in drinking water lowered, after 75 days, the erythrocyte count and haemoglobin concentration (Hb) down to 20-2 % and 4.5 % of those of the controls, respectively. Decreased incorporation of 59Fe into red blood cells and spleen was also observed along with increased 59Fe incorporation into liver and bone marrow.
Male chicks of an egg-laying strain were injected with 0, 1, 2 or 4 micrograms/100 g b. wt thyroxine s.c. daily from 7 to 12 weeks of age. Increasing dose suppressed testicular development and puberty was completely blocked by the highest level. Live weight gain was enhanced by thyroxine treatment. Similar treatment of females prevented normal development of the ovaries at puberty.
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