Effect of exercise on occurrence of diurnal rhythms of plasma ions and metabolites in Thoroughbred racehorses

Records of plasma calcium (Ca++), phosphorus (Pi), potassium (K+), sodium (Na+), chloride (Cl-), magnesium (Mg++), iron (Fe++), glucose, cholesterol, triglycerides and total protein levels were measured to determine the effects of exercise on occurrence of diurnal rhythms in Throughbred racehorses (n=7) under physical training. Physical activities consisted of gallop on the track and walking. Blood samples were collected from jugular vein every 4h over a 48h period. Plasma Ca++, K+, Mg++ and Na+ levels were obtained by flame photometry; and, Pi, Cl-, Fe++, glucose, cholesterol, triglycerides and total protein levels were measured by colorimetric tests using visible UV spectrophotometry. The data were analyzed using a 24h period to each exercise performed. Diurnal rhythm of Pi was observed when walking was the physical activity performed, and its acrophase occurred at the light period. Plasma triclycerides showed significant diurnal rhythms, with their acrophases occurring at the dark period, even when walking or gallop were performed. High intensity exercise (gallop) decreased triglycerides amplitude. No significant diurnal rhythms of other variables were found. Gallop, as physical activity, masked phosphorus diurnal rhythm. However, physical training did not influence triglycerides diurnal rhythm occurrence. High intensity exercise (gallop) just declined triglycerides amplitude

Mensuraram-se as concentrações plasmáticas de cálcio (Ca++), fósforo (Pi), potássio (K+), sódio (Na+), cloreto (Cl-), magnésio (Mg++), ferro (Fe++), glicose, colesterol, triglicerídeos e proteínas totais para determinar os efeitos do exercício sobre a ocorrência dos ritmos diários em cavalos de corrida da raça Puro Sangue Inglês (n=7), em treinamento. A atividade física consistiu de galope na raia e passo. Amostras de sangue foram coletadas da veia jugular a cada 4h durante um período de 48h. As concentrações plasmáticas de Ca++, K+, Mg++ e Na+ foram obtidas por espectrofotometria de absorção atômica com chama, e as concentrações de Pi, Cl-, Fe++, glicose, colesterol, triglicerídeos e proteína total foram mensuradas por testes colorimétricos utilizando-se a espectrometria de luz UV visível. Os dados foram analisados utilizando-se um período de 24h para cada tipo de exercício desenvolvido. Ritmo diário de Pi foi observado quando o passo foi a atividade física desenvolvida, apresentando sua acrofase no período diurno. A concentração plasmática de triglicerídeos mostrou significante ritmo diário com a acrofase ocorrendo no período noturno, independente se foi desenvolvido o galope ou passo. O exercício de alta intensidade (galope) diminuiu a amplitude dos triglicerídeos. Nenhum ritmo diurno foi achado nas outras variáveis. Estes resultados mostram que o galope como atividade física, mascara o ritmo diário do fósforo. Entretanto, o treinamento físico não apresentou nenhum efeito na ocorrência do ritmo diário de triglicerídeos, somente na sua amplitude

Chronobiology courses at the University of São Paulo/Brazil: a four-year experience.

We describe the didactic experience of graduate and post-graduate courses on chronobiology in São Paulo, Brazil.

Perinatal malnutrition, suprachiasmatic nuclear lesioning, and circadian-ultradian aspects of spontaneous behavior of albino rats.

The effect of reducing the dietary protein content at different stages of development was investigated. A group of control rats was fed a diet with 25% protein throughout the entire study. Four other groups were fed only 6% protein in a diet isocaloric with the control diet. In an "intrauterine"-deprivation (prenatal) group, the feeding of the low protein diet was limited to the span from mating to delivery. In a "postnatal"-deprivation (lactation) group, the reduced protein diet was limited to the 25 days allowed for lactation. In a "perinatal"-deprivation group, the low-protein diet was fed during both the pregnancy and the 25 days after birth. Protein deprivation in a "preperinatal" group started 1 month before mating and continued throughout gestation and lactation to day 25 after birth. Except for the perinatal group, consisting of two animals, other groups consisted each of three or four rats. Behavioral variables--activity, rest, eating, drinking, exploring, grooming, curling up, and lying down--were studied in rats from each group at 90 days of age for 3 days at consecutive near-12-min intervals for observation spans of 1 min. Two animals subjected to bilateral suprachiasmatic lesions, subsequently validated histologically, and two sham-operated controls were also investigated. Both the population-mean and the single cosinor methods were used for data analysis in conjunction with linear least-squares spectra. Cosinor methods allow the rejection of the zero-amplitude assumption on a group basis for the intact controls (P = 0.007), the intrauterine malnutrition group (P = 0.034), the lactation group (P = 0.059), the preperinatal group (P = 0.055), and on an individualized basis for the two animals constituting the perinatal group (P = 0.007 and 0.002). These results by population-mean cosinor are complemented by the single cosinor demonstration of rhythms for most animals and variables investigated. The results demonstrate, on an individualized basis, the persistence of circadian rhythms under differently timed conditions of protein malnutrition. The data on the behavior of rats with bilateral lesions of the suprachiasmatic nuclei show a circadian to ultradian variance transposition. In most behaviors, there are prominent ultradian rhythms, which, however, require study over longer spans with dense observations on additional animals.

Sexual behavior elicited in cage-mates of olfactory tubercle stimulated rats.

Fourteen male albino rats kept in pairs were implanted with bipolar electrodes in the olfactory tubercle. Electrical stimulation elicited a behavioral change in the cage-mates of the stimulated rats. This change consisted of increased exploratory activity in six animals. In three of these six rats, sexual behavior with mounting and pelvic thrusting was observed. The changes are described and discussed with special attention to sexual behavior.