Protective effects of taurine on human hair follicle grown in vitro.

Taurine is a naturally occurring beta-amino acid produced by methionine and cysteine metabolism. It is involved in a variety of physiological functions, including immunomodulatory and antifibrotic. Taking advantage of the ability of human hair follicle grown in vitro to recapitulate most of the characteristic features of normal hair follicle in vivo, we studied (i) taurine uptake by isolated human hair follicles; (ii) its effects on hair growth and survival rate; and (iii) its protective potential against transforming growth factor (TGF)-beta1, an inhibitor of in vitro hair growth and a master switch of fibrotic program. We showed that taurine was taken up by the connective tissue sheath, proximal outer root sheath and hair bulb, promoted hair survival in vitro and prevented TGF-beta1-induced deleterious effects on hair follicle.

Central opiate mechanism involved in gastro-intestinal motor disturbances induced by E. coli endotoxin in sheep.

Intravenous injection of small doses of E. coli endotoxin in sheep inhibited phasic contractions of forestomach and altered the myoelectrical activity of the antrum, duodenal bulb and jejunum. Previous intracerebroventricular administration of naloxone at a dose without effect when given intravenously (10 micrograms X kg-1) antagonized the endotoxin-induced inhibition of forestomach and alteration of the gastrointestinal myoelectrical activity.

Antagonistic effects of naloxone on CCK-octapeptide induced satiety and rumino-reticular hypomotility in sheep.

Continuous intracerebroventricular (ICV) infusion of CCK-octapeptide (CCK8) was performed in ewes fitted with a permanent cannula into the lateral cerebral ventricle and Nichrome electrodes on the reticulum in order to record its electrical activity. In the first series of experiments, subsequently repeated in 12 h fasted animals, CCK8 was infused during the first hour of a 3 hour period of feeding at 2.5, 5 and 10 ng.kg-1.min-1. The same series of infusion were performed 20 min after ICV injection of 2.4 and 10 micrograms.kg-1 of naloxone. CCK8 reduced significantly in a dose related manner the food intake (r = 0.95; P less than 0.01) and the frequency of cyclic spike bursts associated to biphasic contractions of the reticulum observed during feeding (r = 0.89; P less than 0.01). At 5 and 10 ng.kg-1.min-1, the reduction of food intake reached 46.2 and 52.6% during the period of infusion; the basal and stimulated (feeding) frequency of reticular contractions were nearly halved. Previous ICV administration of naloxone (2.4 micrograms.kg-1) partially blocked the effects of CCK8 infusion on both food intake (72%) and reticular frequency (54% basal, 67% stimulated). The CCK8 induced effects on both food intake and frequency of reticular contraction were completely abolished after a previous 10 micrograms.kg-1 injection of naloxone. These results suggest that the central effects of CCK8 on feeding behavior and forestomach motility involve similar central structures and are mediated through opiate receptor structures.

Influence of regimen (roughage vs. concentrates) on satiety and forestomach motility in sheep.

The influence of concentrate intake on the subsequent intake of hay was investigated in sheep fitted with a rumen cannula and electrodes on the reticulum wall to measure volatile fatty acids concentration and reticular motility, respectively. In sheep fasted during night time, a previous meal of concentrates given 30, 60 or 120 min before feeding hay, did not modify significantly (p less than 0.05) the first hour and the first 3 hour intake of hay despite a large increase in ruminal total volatile fatty acid concentration. However, the daily intake of hay was significantly (p less than 0.05) reduced. Similarly, the reticular motility in response to feeding hay was not affected by the previous meals of concentrate. It is concluded that in fasted sheep on a hay ration the short-term satiation of a hay meal is not affected by foregoing intake of concentrates and that the hay intake is not controlled by ruminal volatile fatty acid levels.

A possible central opiate mechanism involved in the inhibition of food intake and reticular motility by duodenal DL-lactic acid infusion in sheep.

Intraduodenal infusion of DL-lactic acid was performed in sheep fitted with a permanent cannula into the lateral cerebral ventricle and nichrome electrodes on the reticulum in order to record its electrical activity during periods of controlled food intake in a series of experiments subsequently repeated in animals fasted for 12 hours. A solution of 0.2M DL-lactic acid was infused at a rate of 1 ml/min during the 1st hour of a 3-hour period of feeding with or without previous intracerebroventricular (ICV) or IV administration of naloxone (2.4 and 10 micrograms/kg). During lactic acid infusion, the food intake and the frequency of reticular contraction (measured during eating) were reduced by 48% and 19%, respectively--these effects being prolonged for the 1st hour after infusion. Previous ICV administration of naloxone (2.4 micrograms/kg) partially blocked the effects of lactic acid on food intake (63%) and frequency of reticulum contractions (58%). These effects were abolished for the largest dose of naloxone (10 micrograms/kg) administered ICV, whereas its IV administration did not affect significantly the effects of lactic acid. It is concluded that the duodenal lactic acid concentration may have a role in the control of food intake by a mechanism involving central opiate mediation.