We studied the effect of yohimbine, a drug that inhibits presynaptic alpha 2-adrenergic receptors and increases the neuronal release of norepinephrine from the central and sympathetic nervous systems, on tolerance to cardiovascular stress in 10 untrained, healthy subjects. Using radioligand binding of tritiated yohimbine to platelets, these subjects were found to have a normal complement of alp...

A method using QuEChERS sample preparation and an Agilent 6490 Triple Quadrupole LC/MS has been developed that provides rapid and sub-parts per billion (ppb) detection of synthetic yohimbine and yohimbe bark extract in dietary supplements. Using the chromatographic separation of the diastereomers of yohimbine, the synthetic compound can be distinguished from the tree bark extract. An Agilent 65...

The ability of the alpha adrenoreceptor antagonists phentolamine and yohimbine to antagonize cocaine-induced hepatotoxicity was determined in phenobarbital-induced B6C3/F1 mice. Hepatotoxicity was assessed by the histologic extent of necrosis, incidence of latent lethality and increases in serum alanine aminotransferase activity. The depression of hepatic glutathione levels also were measured. ...

the involvement of supraspinal alpha-adrenergic receptors in tonic pain was assessed in formalin-induced pain in rats. the alpha2 adrenoceptor agonist clonidine, along with yohimbine and prazosin, α2 and α1 receptor antagonists, were introduced intracerebroventrically (icv) and/or systemically in different doses. the data show that 1) clonidine exerts an alpha adrenergic analgesic effect, in ad...

Exaggerated response to alpha2-adrenergic receptor (alpha2-AR) blockade by yohimbine in normotensive subjects is an intermediate phenotype that predicts increased risk for development of hypertension. Here, we assessed the 3 alpha2-AR loci (alpha2A, alpha2B, alpha2C) as candidate genes for their influence on baseline and yohimbine-mediated increase in mean arterial pressure. Because initial res...

Stress promotes a shift from goal-directed action-outcome learning toward habitual stimulus-response learning. This shift is mediated by an interaction of noradrenergic activity and glucocorticoid stress hormones. In the present experiment, we examined the neural correlates of the stress (hormone)-induced shift from goal-directed to habit learning in the human brain. Healthy participants were a...

Alpha2-adrenergic receptor activation plays an important role in the development of postoperative ileus. Alpha2-adrenergic receptors also regulate nitric oxide (NO) production by the mononuclear phagocyte system. We have previously shown that intestinal manipulation leads to a significant increase in NO production by infiltrating monocytes within the intestinal muscularis. The purpose of this s...

BACKGROUND Consistent with many studies demonstrating enhanced reactivity of the sympathetic nervous system in posttraumatic stress disorder (PTSD), the administration of yohimbine, a noradrenergic alpha(2)-antagonist, has been shown to increase core symptoms of PTSD and to induce greater increases in plasma 3-methyl-4-hydroxy-phenyl-glycol (MHPG) in subjects with PTSD compared with healthy con...

The present study was undertaken to look for the effect of chloroethylclonidine (CEC) on prejunctional alpha-2 autoreceptors of the canine saphenous vein. The effect was tested on tritium overflow evoked by electrical stimulation from tissues preloaded with 0.2 microM 3H-norepinephrine. Yohimbine (3-300 nM) and CEC (1-125 microM) increased and UK-14,304 reduced the overflow of tritium evoked by...