Influence of supplemental magnesium, tryptophan, vitamin C, and vitamin E on stress responses of pigs to vibration.

Our objectives were to investigate and compare the effects of supplemental Mg, Trp, vitamin E (vit E), and vitamin C (vit C) on stress responses of pigs undergoing transport simulation. In this study, 126 pigs (25.1 +/- 4.4 kg BW) were allocated to one of the six following treatments: 1) negative control (no supplementation); 2) positive control (i.m. injection with 0.5 mg of carazolol/20 kg BW 12 h before vibration, beta-blocker); 3) Trp (additional amount of 6 g/kg of feed for 5 d, as-fed basis); 4) Mg (3 g/L drinking water for 2 d); 5) vit E (additional amount of 150 mg/kg of feed for 21 d, as-fed basis); 6) or vit C (additional amount of 300 mg/kg of feed for 21 d, as-fed basis). Pigs were treated in groups of three, and each treatment was replicated seven times. Feed and water intake were not different among treatments. Heart rate variables (mean, peak, and minimum heart rate, ventricular ectopic beats, and ST elevation of Channels A and B) and heart rate variability were registered from the night before vibration. Pigs were subjected to vibration in a transport simulator (8 Hz, 3 m/s) for 2 h and allowed to recover for 2 h. Generally, the positive control pigs had the lowest heart rate values (mean, peak, minimum heart rate, ST elevation of Channel A; P < 0.05), whereas Mg and Trp decreased ventricular ectopic beats and ST elevation of Channel B, respectively. The effect of vit C and E as vagal stimulators was clearly visible, whereas carazolol and Mg clearly blocked the sympathetic pathways of the autonomic nervous system. During vibration, the negative control pigs lay the least, and Mg pigs the most (P < 0.05). Salivary cortisol concentrations (taken before and after vibration and after recovery) showed that vit E pigs produced the least cortisol during stress periods. Intermediary metabolites (glucose, lactate, creatine kinase, and NEFA) were analyzed in plasma from blood taken before and after vibration. At the two sampling points, the vit E and Mg pigs had the lowest NEFA concentrations (P < 0.05), and the vit E pigs also had the lowest lactate concentrations before vibration. Urine samples were collected before and after vibration to determine catecholamine concentrations; only negative control pigs had an increase (P = 0.04) in epinephrine concentration, despite large individual variation. In general, these results indicate that the supplementation of Trp, Mg, vit E, or vit C improved coping ability of pigs during vibration comparison with the negative control treatment. A muscular injection of carazolol influenced only the heart rate variables.

Tryptophan and tyrosine availability and response to antidepressant treatment in major depression.

BACKGROUND: It has been suggested that the ratio of tryptophan (TRP) and tyrosine (TYR) to other large neutral amino acids may predict response to antidepressant drugs with predominantly serotonergic compared with predominantly noradrenergic activity and that this may be clinically useful. METHOD: 147 subjects with a DSM-III-R diagnosis of major depression underwent a detailed clinical evaluation and prior to treatment had baseline measures of TRP, TYR and other large neutral amino acids (LNAA), prolactin and cortisol. Subjects entered a 6-week randomised treatment trial comparing fluoxetine and nortriptyline. RESULTS: There was no main effect on 6-week outcome of TRP/LNAA ratio or TYR/LNAA ratio and no interaction between these factors and treatment (fluoxetine vs nortriptyline). LIMITATIONS: Alterations in antidepressant dose were allowed therefore possibly reducing the effect of TRP or TYR availability on response. CONCLUSIONS: Previous findings that TRP/LNAA and TYR/LNAA ratios may predict differential response to antidepressants were not replicated and neither was our previous finding of a complex relationship between TRP/LNAA and baseline prolactin in predicting 6-week response.