title: Seasonal variations in circadian rhythm of hypothalamic catecholamine content in the eel (Anguilla anguilla L.).
abstract: 1. Changes in catecholamine content (CA) in hypothalamus of male and female eel (Anguilla anguilla L.) were defined using the Falck-Hillarp histochemical fluorescence method for a 24-hr period during the summer (L:D = 16:8) and winter (L:D = 8:16). 2. A circadian rhythm in the catecholamine content was found in the hypothalamus. CA content was lower by night than by day. 3. A longer light day (summer period) caused the shifting of rhythm phase in CA content. 4. Sex of eels does not affect CA content in the hypothalamus.
mesh_terms: D000811:Anguilla / Q000378:metabolism*; D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D002940:Circadian Rhythm; D005260:Female; D006651:Histocytochemistry; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D008856:Microscopy, Fluorescence; D012621:Seasons
chemical_list: D002395:Catecholamines