Sex differences in stress reactivity of hippocampal BDNF in mice are associated with the female preponderance of decreased locomotor activity in response to restraint stress.

The incidence and prevalence of depression is higher in women than in men, but the cause of this sex discrepancy remains unknown. Brain-derived neurotrophic factor (BDNF) is a key protein for maintaining neuronal integrity. The purpose of this study was to investigate the female preponderance in behavioral responsivity to restraint stress focusing on the stress reactivity of BDNF in the hippocampus. Male and female ICR mice were exposed to a 3-h session of restraint stress. Plasma corticosterone was measured by high-performance liquid chromatography. BDNF mRNA expression in the whole hippocampus was measured by quantitative real-time reverse transcription-polymerase chain reaction. Wheel-running activity was monitored during the dark period. In response to restraint stress, the increase in levels of serum corticosterone was higher in female than in male mice. Restraint stress resulted in decreased voluntary wheel-running behavior that was greater in female than male animals. In addition to these sex differences in stress reactivity, we found a significant sex difference in BDNF levels in the hippocampus of restraint-stressed mice; total BDNF levels significantly decreased in female mice, but not in male mice in response to the stress. Furthermore, BDNF exon I and IV mRNA expression also showed the same tendency. These data indicate that the reduction in levels of voluntary wheel-running activity in response to stress can be significantly influenced by sex. Moreover, our findings suggest a link between the sex differences in this behavioral response to stress and differential stress reactivity in the production of BDNF in the hippocampus.

Difficulty for consumers in choosing commercial bilberry supplements by relying only on product label information.

BACKGROUND: Various kinds of bilberry supplements have recently become available on the market. However, it is doubtful whether consumers receive accurate information to be able to compare different supplements. OBJECTIVE: We aimed to investigate whether consumers can obtain the expected benefits by relying only on the information printed on the product labels of commercial bilberry supplements. MATERIALS AND METHODS: The quality of 20 supplements was investigated by the spectrophotometric method and ultra high performance liquid chromatography (UHPLC). Each peak was identified by liquid chromatography-mass spectrometry and quantified using an external standard. The percentage of the actual measured value relative to the indicated value on the product label was determined using the spectrophotometric method. The daily dosage was calculated from the total amount of anthocyanins quantified by UHPLC and information on the product label. RESULTS: In 14 of 20 supplements, the total anthocyanin content expressed as delphinidin equivalents was within 20% of the labeled value. However, the extent of degradation could not be determined by the spectrophotometric method. In fresh bilberry fruit, anthocyanidins were barely detected. In 8 of 20 supplements, the anthocyanidin content was >1.0%. The daily dosage of anthocyanins varied by about 66-fold among supplements, and the dosage of 6 supplements was less than the recommended level in Japan. CONCLUSIONS: Consumers cannot always obtain the expected benefits by relying only on product label information. Therefore, new rules concerning product label information are required to make it possible for consumers to take the equivalent amounts of anthocyanins for whichever bilberry supplement they choose.

Degradation Index for quality evaluation of commercial dietary supplements of bilberry extract.

In recent years, many anthocyanin-containing dietary supplements of various dosages and formulations have been sold through advertising their large number of beneficial effects. On the other hand, there is an increased risk of distributing deteriorated supplements to consumers due to lax regulations, because in Japan these supplements are classified as food. Spectrophotometric methods are commonly used to control the quality of supplements. However, these methods have limitations with regard to assessing deterioration. In this study, we evaluated a new index for detection of deteriorated products. The stability of 3 formulations and the quality of 20 supplements were investigated by ultra-high performance liquid chromatography, which is superior to spectrophotometry for identifying and quantifying individual anthocyanins. The stability was not only affected by storage temperature but also by formulation. We defined "Degradation Index" (DI) as an indicator of the deterioration of supplements. Of 20 supplements investigated, the DI of 5 supplements was more than 3-fold the value of Bilberon-25, and the worst one was 12.7-fold. These results suggest that DI could be a useful quality control index for detecting deteriorated supplements.

Anthocyanins, but not anthocyanidins, from bilberry (Vaccinium myrtillus L.) alleviate pruritus via inhibition of mast cell degranulation.

We have previously reported that bilberry anthocyanins exhibit an anti-pruritic effect in a mouse model of allergic contact dermatitis. It has been reported that anthocyanins are particularly sensitive to thermal treatment and are easily hydrolyzed to anthocyanidins when exposed to high temperatures. The objective of this study was to compare the anti-pruritic effect of anthocyanin-rich quality-controlled bilberry extract and anthocyanidin-rich degraded extract using a mouse model of allergic contact dermatitis. BALB/c mice with allergic contact dermatitis induced by 4 weeks of repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB) were administered Bilberon-25 orally for 4 weeks after sensitization with TNCB. The effect of Bilberon-25 on pruritus was evaluated by measurement of scratching behavior. RBL-2H3 mast cells were used to investigate the effect of Bilberon-25 on degranulation in 48/80-stimulated mast cells. Compared with nonheated Bilberon-25, the proportion of anthocyanins in heated Bilberon-25 decreased, and the proportion of anthocyanidins was increased in heated-time dependent manner. Treatment with non-heated Bilberon-25 significantly attenuated the TNCB-induced increase in scratching behavior, whereas treatment with 2 h-heated Bilberon-25 did not. Moreover, 300 µg/mL nonheated Bilberon-25 showed significant inhibition of degranulation in RBL-2H3 mast cells, whereas 2 h-heated Bilberon-25 had no effect at any concentration studied. It is assumed that the inhibitory effect of bilberry anthocyanins on pruritus might be mediated, at least in part, by its inhibitory effect on mast cell degranulation. In conclusion, the anthocyanin-rich but not anthocyanidin-rich bilberry extract may be a useful dietary supplement for skin diseases involving pruritic symptoms, such as chronic allergic contact dermatitis, atopic dermatitis, and rhinitis.