The bovine protein alpha-lactalbumin increases the plasma ratio of tryptophan to the other large neutral amino acids, and in vulnerable subjects raises brain serotonin activity, reduces cortisol concentration, and improves mood under stress.
BACKGROUND: Increased brain serotonin may improve the ability to cope with stress, whereas a decline in serotonin activity is involved in depressive mood. The uptake of the serotonin precursor, tryptophan, into the brain is dependent on nutrients that influence the cerebral availability of tryptophan via a change in the ratio of plasma tryptophan to the sum of the other large neutral amino acids (Trp-LNAA ratio). Therefore, a diet-induced increase in tryptophan availability may increase brain serotonin synthesis and improve coping and mood, particularly in stress-vulnerable subjects. OBJECTIVE: We tested whether alpha-lactalbumin, a whey protein with a high tryptophan content, may increase the plasma Trp-LNAA ratio and reduce depressive mood and cortisol concentrations in stress-vulnerable subjects under acute stress. DESIGN: Twenty-nine highly stress-vulnerable subjects and 29 relatively stress-invulnerable subjects participated in a double-blind, placebo-controlled study. Subjects were exposed to experimental stress after the intake of a diet enriched with either alpha-lactalbumin or sodium-caseinate. Diet-induced changes in the plasma Trp-LNAA ratio and prolactin were measured. Changes in mood, pulse rate, skin conductance, and cortisol concentrations were assessed before and after the stressor. RESULTS: The plasma Trp-LNAA ratio was 48% higher after the alpha-lactalbumin diet than after the casein diet (P = 0.0001). In stress-vulnerable subjects this was accompanied by higher prolactin concentrations (P = 0.001), a decrease in cortisol (P = 0.036), and reduced depressive feelings (P = 0.007) under stress. CONCLUSIONS: Consumption of a dietary protein enriched in tryptophan increased the plasma Trp-LNAA ratio and, in stress-vulnerable subjects, improved coping ability, probably through alterations in brain serotonin. (+info)
Sensory modalities conveyed in the hindlimb somatic afferent input to nucleus tractus solitarius.
To determine the somatic sensory modalities conveyed by hindlimb somatic afferent inputs, the discharge of neurons in the nucleus tractus solitarius was recorded in anesthetized rats after electrical stimulation of either the contralateral sciatic nerve or L(6) spinal nerve, which innervates the hindlimb. The discharge of seven of eight cells was increased (P < 0.05) by capsaicin injected into the arterial supply of the hindlimb. Discharge was unaltered in 19 neurons tested for sensitivity to nonnoxious (40 degrees C) and noxious (47 degrees C) heating of the hindlimb skin. In contrast, lightly stroking the skin elicited discharge in 2 of 14 cells, whereas noxious pinching increased activity in 4 other cells. Rhythmic (1- to 3-s) muscle contraction (MC) increased (P < 0.05) discharge in >60% of neurons tested (11 of 18). Static (10- to 30-s) MC significantly (P < 0.05) increased discharge in four cells, two of which were also responsive to rhythmic MC. Rhythmic and sustained muscle stretch increased discharge (P < 0.05) in three of eight neurons tested. These data indicate that nucleus tractus solitarius neurons receive input from low- and high-threshold cutaneous mechanoreceptors, respond to capsaicin delivered into the hindlimb arterial supply, lack thermal sensitivity, and respond to activation of mechanosensitive as well as metabosensitive endings in skeletal muscle. (+info)
Effects of skin pressure applied by cuffs on resting salivary secretion.
The effects of pressure applied by cuffs to the abdomen, thighs and legs on resting salivary flow rate and digestive function of saliva were investigated in 9 healthy female students, aged 18 to 33 yrs (Experiment I) in a climatic chamber (Ta: 28 degrees C, RH: 50%). Each participant changed from street clothing into loose-fitting experimental garments so as to avoid any skin pressure on the body, and sat calmly in a reclining chair throughout the experimental period (195 min). After 90 min (FREE period), the physiological effects of skin pressure applied by their own clothing disappeared, and skin pressure was applied for the next 60 min to the abdomen (40 mmHg) and thighs (40 mmHg) then to the legs (60 mmHg) by the use of air-inflated cuffs (PRESSURE period). During the next 45 min, the skin pressure was again removed by letting the air of the cuffs out (FREE' period). The resting salivary flow rate was significantly suppressed while the skin pressure was applied by the cuffs. The digestive time for starch investigated in terms of the iodine starch reaction was longer with the skin pressure than without. The concentration of amylase measured in 20 female participants aged 21 to 23 yrs, decreased with skin pressure applied by the usage of the rubber tape (Experiment II). These results suggest that the pressure applied to the body can influence the digestive response by decreasing the amount of saliva via the autonomic nervous system. (+info)
Sympathetic vasodilatation in human limbs.
This review focuses on recent developments in our understanding of active vasodilatation in human skin and skeletal muscle. We have attempted to place recent advances in their historical context and review the evolution of thinking on active vasodilatation in these two vascular beds. In human skin, active vasodilatation is well established, but the neurotransmitter responsible for the dilatation is unknown. In human skeletal muscle, older studies provided circumstantial evidence consistent with sympathetically mediated vasodilatation, but the evidence was never unambiguous. By contrast, recent studies on active vasodilatation in human skeletal muscle in conjunction with a reinterpretation of data from previous studies casts doubt on the existence of sympathetic vasodilator fibres in human skeletal muscle. (+info)
The effects of skin pressure by clothing on whole gut transit time and amount of feces.
The experiment investigated the effects of skin pressure by clothing on whole gut transit time and amount of feces. Comparisons of transit time and amount of feces were taken between 6 young female adults with and without a girdle. The skin pressure applied by a girdle (mean +/- SD) on participant's waist, abdomen and hip region was 16.6 +/- 7.80 mmHg, 17.1 +/- 4.5 mmHg and 12.6 +/- 5.0 mmHg, respectively. The difference of skin pressure with and without a girdle was about 10 mmHg. During each experimental period of 4 days with and without a girdle, the whole gut transit time and amount of feces were measured. The whole gut transit time of each day was determined as the time between the oral intake of each day's markers and their first appearance in the stool. The whole gut transit times of the markers taken on the first day were significantly prolonged (p < 0.05) and those of the markers taken on the second day tended to be prolonged for participant using a girdle (p < 0.1). The whole gut transit time of the markers taken on the third day could not be compared because they were not excreted into the stool. The cumulative increases of feces on the third day and the fourth day were significantly reduced with a girdle (p < 0.05). These results indicate that the skin pressure by clothing has an effect on whole gut transit time and the amount of feces. (+info)
Effects of skin pressure by clothing on digestion and orocecal transit time of food.
In order to reveal the influence of clothing skin pressure on digestion of food through the gastrointestinal tract, we examined the absorption of dietary carbohydrate and orocecal transit time of a test meal by means of a breath hydrogen test on 7 healthy young women. In this experiment, we collected breath samples from the participants wearing loose-fitting experimental garment on the second day of the experiment and from the same participants but wearing an additional tight-fitting girdle on the following day for 16 hours and 9 hours, respectively. Skin pressure applied by a girdle on participant's waist, abdomen and hip region was 15.5 +/- 0.4 mmHg (mean +/- SE), 11.0 +/- 0.2 mmHg, and 13.6 +/- 0.6 mmHg, respectively, and the values were 2-3 times larger than those of the experimental garment. The hydrogen concentration vs. time curve showed that breath hydrogen levels at its peaks (15:00, 15:30, 16:00, 16:30, and 17:00 hr) on the third day of the experiment were significantly higher than those of the corresponding time on the second day (p < 0.05 at 17:00 and 15:00, p < 0.01 at 15:00, 16:00 and 16:30). Consequently, significantly pronounced breath hydrogen excretion was observed under the "pressure" clothing condition (p < 0.01). On the other hand, the transit time of the test meal for the subjects wearing a girdle did not differ significantly from that for the subjects wearing the garment of less pressure (270 +/- 18 minutes and 263 +/- 21 minutes, respectively). These results indicate that the clothing skin pressure has an inhibitory effect on the absorption of dietary carbohydrate in the small intestine, but no effect on the orocecal transit time of a meal. (+info)
Free cholesterol enhances adenoviral vector gene transfer and expression in CAR-deficient cells.
Efficient adenovirus vector-mediated gene transfer depends on the presence of sufficient amounts of the high-affinity coxsackie-adenovirus (Ad) receptor (CAR) on the surface of the target cell leading to receptor-mediated endocytosis of the vector. The present study evaluates the effect of free cholesterol, a lipid component of endocytic vesicles, on Ad uptake into CAR-deficient cells. Infection in the presence of free cholesterol at its maximum solubility in water led to increased binding, uptake, and expression of Ad in human skin fibroblasts and alveolar macrophages, two primary human cells known to be deficient in CAR. The effect of free cholesterol was maximal at its solubility maximum in aqueous solution. Increase of Ad vector-mediated gene transfer with cholesterol was dependent on the lack of CAR receptor expression on the surface and was diminished by overexpression of CAR in CAR-deficient cells. Cholesterol-mediated increase of Ad-mediated gene expression was dependent on coincubation of both cholesterol and Ad and was not dependent on the cholesterol content of the cell. Increased Ad vector-mediated gene expression in the presence of free cholesterol was also observed in murine skin in vivo. Structural analysis of the Ad-cholesterol mixture showed complexation between Ad particles leading to formation of multivirus aggregates due to hydrophobic interaction. The addition of free cholesterol with Ad vectors may be a simple way to increase Ad-mediated gene transfer to cells that are poor targets due to their lack of a sufficient number of Ad receptors. (+info)
Down-regulation of p63 is required for epidermal UV-B-induced apoptosis.
In the epidermis, p53 plays an important role in UV-B protection that led us to examine the role, if any, that p63, a p53 homologue highly expressed in the basal layer of the epidermis, might play in the epidermal UV-B response. One p63 isoform, deltaNp63alpha, decreased dramatically in normal keratinocytes or newborn epidermis at both the protein and RNA levels after UV-B irradiation. In an attempt to further investigate the significance of the UV-B-induced decrease of this p63 isoform as well as further delineate the function of p63 in the epidermis, we generated transgenic mice that constitutively express deltaNp63alpha in the mouse epidermis using the loricrin promoter (ML.deltaNp63alpha). The ML.deltaNp63alpha mouse epidermis developed normally, with no overt phenotype and an unaltered proliferation rate. When challenged by UV-B exposure, the ML.deltaNp63alpha mice exhibited a 40-45% decrease in the number of apoptotic cells in the epidermis as compared with nontransgenic littermates. These results suggest that aberrant expression of deltaNp63alpha altered the UV-B-induced apoptotic pathway in the transgenic epidermis, proving that down-regulation of deltaNp63alpha in response to UV-B is important to epidermal apoptosis. The forced overexpression of deltaNp63alpha may act via a dominant negative effect on the endogenous p53 transcriptional activity required for UV-B-induced apoptosis. (+info)