The effect of light conditions on the content of selected active ingredients in anatomical parts of the oyster mushroom (Pleurotus ostreatus L.).

This study aimed to evaluate the effect of cultivation conditions in the context of light on the retention of selected vitamins, minerals and polyphenols in the stem and cap of the oyster mushroom (Pleurotus ostreatus L.). Additionally, the effect of the retention of bioactive components on the antioxidant activity of mushroom extracts was evaluated, taking into account the morphological part. Oyster mushrooms grown in the light of 200 lux had higher riboflavin content compared to mushrooms exposed to the light of lower intensity. The thiamine content of the mushrooms dropped with decreasing light intensity during cultivation. The content of biologically active compounds was found to be equal in the stem and the cap. In the case of riboflavin, it was shown that its contents in cap fractions, irrespective of the cultivation method, was statistically significantly higher than in stems. The mineral composition of caps and stems differed from each other. No differences in Zn and Cu content between the morphological parts of the mushroom studied were found. However, it was shown that the stems, regardless of the type of light, contained less iron, magnesium and sodium. Thus, it was observed that limited light exposure caused an increase in the content of total polyphenolic compounds, which did not correlate with antioxidant activity. There was no effect of the light on the antioxidant activity of mushrooms. It was also shown that stem extracts had higher antioxidant activity compared to the extracts obtained from the caps. This findings point to the possibility and potentail of use both fraction of mushrooms in the new food products development.

Preliminary immunohistochemical investigations of thyroid C cells in an experimental model of hyperthyroidism.

The role of the parafollicular (C) cells, the second most important cells in the thyroid gland, has not hitherto been clarified. They are considered to be disperse neuroendocrine cells of the APUD system and synthesise and release many of the regulatory peptides. Few publications are concerned with the evaluation of the structure and function of C cells in the thyroid gland or the probable relationship between these cells and the follicular cells in physiological and pathological conditions. For this reason immunohistochemical investigations were carried out into the activity of the C cells in rats in an experimental model of hyperthyroidism caused by chronic thyroxine influence. This C-cell activity was then evaluated. Differences in the quantity, distribution and calcitonin immunoreactivity of C cells were observed in hyperthyroid rats in comparison to the control group, together with a significant diminution of plasma TSH and calcitonin levels. Our preliminary study may indicate a functional interaction between follicular and parafollicular cells in the thyroid gland.

Cannabinoids alter recognition memory in rats.

Cannabinoids are known to attenuate learning and memory in both humans and animals. In rodents, disruptive effect of cannabinoids on memory, reversed by SR 141716, a specific CB(1) receptor antagonist, was shown in behavioral tests based on conditioning. There are no data concerning the influence of cannabinoids on recognition memory. Recently, the improvement of recognition memory in cannabinoid CB(1) receptor knock-out mice was reported. Therefore, the purpose of the present study was to determine whether a stable analogue of endogenous cannabinoid anandamide, R-(+)-methanandamide (0.25 and 2.5 mg/kg, i.p.) and a potent CB(1) receptor agonist, CP 55,940 (0.025 and 0.25 mg/kg i.p.) affect recognition memory in rats evaluated in an object recognition test, based on discrimination between the familiar and a new object presented at 1h interval. Because cannabinoids at the higher doses can produce motor inhibition, the influence of both compounds on psychomotor activity was evaluated in an open field test. CP 55,940 and R-(+)-methanandamide, at both doses given once, 15 min before the learning trial, significantly attenuated recognition memory, measured by the difference in exploration of a new object and a duplicate of the familiar object. Moreover, CP 55,940 at the higher dose significantly attenuated ambulation, and bar approaches, and at both doses also rearings, evaluated in an open field, performed immediately after an object recognition test, while R-(+)-methanandamide at both doses did not alter locomotor and exploratory activity of rats. This is the first evidence that cannabinoids impair recognition memory in rats.