In this study the effect of adrenergic receptor agonists and antagonists on physostigmine induced yawning was investigated. Intraperitoneal injection of different doses of physostigmine (0.03, 0.05, 0.1 and 0.2 mg/kg) caused yawning in white rats. The greatest response was seen at a dose of 0.2 mg/kg physostigmine. Phenylephrine, an α1 agonist, and clonidine, an α2 agonist, led to a decrease in...

Isolated superfused rat atria release [H]acetylcholine when depolarized with 57 mM potassium. The depolarization-induced overflow of [H]acetylcholine is markedly inhibited by micromolar concentrations of epinephrine and norepinephrine. The a,-selective adrenergic agonist methoxamine also inhibits tritium overflow, but the «2-selective adrenergic agonist clonidine and the 0-adrenergic agonist is...

a-Methyldopa acts through a metabolite in the central nervous system. Of the three metabolites most prominently considered as potential mediators of a-methyldopa hypotension — amethyldopamine, a-methylnorepinephrine (MNE), and a-methylepinephrine (ME) — ME is the most potent depressor agent following intravenous infusion into rats, following injection into the lateral ventricle, and following i...

Normal cardiovascular regulation requires intact baroreflex regulation. The efferent portion of the baroreflex arc, which is composed of parasympathetic and sympathetic nerves, is particularly important in this regard. Autonomic failure ensues when the efferent arc is interrupted. Neuronal degeneration within the brain or in the periphery,1,2 enzymatic defects in catecholamine synthesis,3 and a...

Overcoming our fears is on everyone’s “to do” list. However, this is more difficult for some than others, especially those suffering from posttraumatic stress disorder (PTSD). To understand how the brain learns to feel safe, researchers have turned to extinction of classically conditioned fear. In extinction, mice learn that a tone previously paired with a footshock no longer predicts the shock...

In the current study, a number of alkaloids including retamine, cytisine, and sparteine (quinolizidine-type), yohimbine and vincamine (indole-type), scopolamine and atropine (tropane-type), colchicine (tropolone-type), allantoin (imidazolidine-type), trigonelline (pyridine-type) as well as octopamine, synephrine, and capsaicin (exocyclic amine-type) were tested in vitro for their inhibitory act...

Noradrenergic neurotransmission has been associated with the modulation of higher cognitive functions mediated by the prefrontal cortex. In the present study, the impact of noradrenergic stimulation on the human action-monitoring system, as indexed by event-related brain potentials, was examined. After the administration of a placebo or the selective alpha2-adrenoceptor antagonist yohimbine, wh...

The aim of current investigation was the validation of HPLC method with UV-detection for identification and determination of Yohimbine by using column Spherisorb ODS RP C18 (250 mm x 4.6 mm x 5 μm), temperature: 25 oC, mobile phase: methanol : acetonitrile : water = 70 : 20 : 10 v/v, flow rate: 2 ml/min., UV-detection: λ = 270 nm. HPLC method was validated in accordance of linearity, limit of d...

Sepsis induces hepatic injury but whether alpha-2 adrenoceptor (α2-AR) modulates the severity of sepsis-induced liver damage remains unclear. The present study used lipopolysaccharide (LPS) to induce hepatic injury and applied α2-AR agonist dexmedetomidine (DEX) and/or antagonist yohimbine to investigate the contribution of α2-AR in LPS-induced liver injury. Our results showed that LPS resulted...