Brain thyrotropin-releasing hormone content varies through amygdaloid kindling development according to afterdischarge frequency and propagation.

PURPOSE: Thyrotropin-releasing hormone (TRH), present in extra hypothalamic brain areas, has been proposed to have neuromodulatory functions and to be susceptible to change by electrical stimulation paradigms. We measured TRH concentrations of several brain areas during kindling development before its establishment and determined whether the changes detected in TRH levels were related to the behavioral stages of kindling, the number of stimulations required to reach these stages and, with the electrophysiological parameters characteristic of this paradigm (amygdaloid afterdischarge (AD) frequency, duration, and propagation). METHODS: Male Wistar rats were implanted stereotaxically with indwelling bipolar electrodes in the basolateral nucleus of the amygdala and with two stainless-steel electrodes epidurally in frontal cortex. Amygdaloid kindling was induced by daily electrical stimulation; AD frequency and duration were recorded and analyzed throughout the development of kindling. TRH was extracted from several regions and quantified by radioimmunoassay (RIA). RESULTS: Modifications in TRH concentrations were detected, depending on the region assayed, from stage II of kindling. A positive correlation was noted between the levels of TRH and the frequency and propagation of AD, but not with the number of stimulations. The rate of change in TRH concentration in relation to AD frequency or duration was highest in frontal cortex followed by hippocampus and amygdala. CONCLUSIONS: A graded response was noted in the increase in TRH concentration dependent on the increase of AD frequency and propagation. The rate of response correlated with the region's epileptogenic susceptibility.

Pigmentation of the rainbow trout (Oncorhynchus mykiss) with oil-extracted astaxanthin from the langostilla (Pleuroncodes planipes).

The effect of oil-extracted astaxanthin from the red crab or langostilla (Pleuroncodes planipes) on the growth and pigmentation of forty five rainbow trouts (Oncorhynchus mykiss) was investigated by feeding a test diet supplemented with 75 mg/kg of astaxanthin during six weeks and compared with a control diet. The oil-extraction process of the pigment is described. Weight, flesh astaxanthin concentration, and color (L*, a*, b*) of the flesh were measured at 0, 3, and 6 weeks. No apparent effect of astaxanthin supplementation was observed on fish development. In spite of the low free astaxanthin amount in the diet (8%), an acceptable carotenoid concentration in the flesh (3.60 +/- 0.78 mg/kg, w/w), and a red hue (H(ab)o = 44.13 +/- 2.36) were obtained at the end of the study. The red hue was strongly correlated with the carotenoid concentration (r = 0.98).

[Effect of the light-dark cycle over the growth of male rats with different health status]. / Influencia del ciclo luz-oscuridad en el crecimiento de ratas macho con diferente estado de nutrición.

The light-dark cycle exerts an influence over the lipostatic mechanism in the superior vertebrate animals promoting an acceleration in the lipid synthesis rate during the dark period (in the case of rodents) and a higher lipolitic rate during the day. This cycle, the feeding habits, and the awake-sleep cycle are syncronized. The Growth Hormone is a molecule that facilitates the lipolysis and the protein synthesis. This hormone is released, by the pituitary gland, during the puberty and during the short wave sleep period. Modifying the light-dark cycle and in consequence the sleep-awake cycle and the food consumption, we pretend to study its influence over the growth rate in weight and length in animals that consume 100% of its nutritional requirements. Also want to dilucidate if an alteration of the cycle (18 h light 6 h dark) in the malnourished animals can revert the deficiency of the growth rate expected in these animals. Male Wistar rats (160); 21 days old, adapted to the temperature and to the light-dark cycle (12 h-12 h) during a week. Then, four groups were formed; Group I: Well nourished rats with a light-dark (12 h-12 h) cycle; Group II: Well nourished rats with a light-dark (18 h-6 h) cycle; Group III: Malnourished rats with a light-dark (12 h-12 h) cycle; Group IV: Malnourished rats with a light-dark (18 h-6 h) cycle. Its length and weight were registered weekly, obtained its growth rates, and the results were analysed by the ONE-WAY ANOVA and orthogonal contrasts. It was found a significant difference in the growth rate in weight between the Groups I and II; the growth rate in weight in the Group III had a higher slope than the rate in the Group IV but we did not find a significant difference. The growth rate in length did not show a significant difference between the Groups III and IV. The last weight in the malnourished animals represented 55% of the control animals last weight; and 47% of the Group IV. The last length of the animals of the Group III represented 90% of the control value, and the last length in the Group IV represented 82% of the control animals value. The feeding habits are modified changing the cycle to 18 h light and 6 h dark. Modifying the light-dark cycle appears an accelerating rate in the growth rate in weight in the well nourished animals, but not in the malnourished ones.