title: Effect of a high-fat diet on 24-h pattern of circulating levels of prolactin, luteinizing hormone, testosterone, corticosterone, thyroid-stimulating hormone and glucose, and pineal melatonin content, in rats.
abstract: Circadian rhythmicity is affected in obese subjects. This article analyzes the effect of a high-fat diet (35% fat) on 24-h changes circulating prolactin, luteinizing hormone (LH), testosterone, corticosterone, thyroid-stimulating hormone (TSH) and glucose, and pineal melatonin content, in rats. When body weight of rats reached the values of morbid obesity, the animals were sacrificed at six different time intervals throughout a 24-h cycle, together with age-matched controls fed a normal diet (4% fat). Plasma hormone levels were measured by specific radioimmunoassays and glucose concentration by an automated glucose oxidase method. In rats under a high-fat diet, a significant disruption of the 24-h pattern of plasma TSH, LH, and testosterone and a slight disruption of prolactin rhythm were found. Additionally, high-fat fed rats showed significantly lower total values of plasma TSH and testosterone and absence of correlation between testosterone and circulating LH levels. Plasma corticosterone levels increased significantly in high-fat fed rats and their 24-h variation became blunted. In obese animals, a significant hyperglycemia developed, individual plasma glucose values correlating with circulating corticosterone in high-fat fed rats only. The amplitude of the nocturnal pineal melatonin peak decreased significantly in high-fat fed rats. The results underlie the significant effects that obesity has on circadian organization of hormone secretion.
authors.affiliation: Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, Madrid, 28040, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Cano
authors.forename: Vanesa
authors.initials: V
authors.lastname: Jiménez-Ortega
authors.forename: Alvaro
authors.initials: A
authors.lastname: Larrad
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Reyes Toso
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Cardinali
authors.forename: Ana I
authors.initials: AI
authors.lastname: Esquifino
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001835:Body Weight / Q000187:drug effects; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood; D004032:Diet / Q000009:adverse effects*; D004041:Dietary Fats / Q000494:pharmacology*; D006728:Hormones / Q000097:blood*; D006943:Hyperglycemia / Q000097:blood / Q000139:chemically induced; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008550:Melatonin / Q000378:metabolism; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D013739:Testosterone / Q000097:blood; D013972:Thyrotropin / Q000097:blood
chemical_list: D001786:Blood Glucose; D004041:Dietary Fats; D006728:Hormones; D013739:Testosterone; D011388:Prolactin; D007986:Luteinizing Hormone; D013972:Thyrotropin; D008550:Melatonin; D003345:Corticosterone