• Environmental Mutagens and Carcinogens
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• v.22 no.1
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• pp.39-46
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• 2002

Obesity is a complex metabolic disorder with a strong genetic component. There are many candidate genes for obesity and its related phenotypes. We studied genetic variations between Korean obese and lean groups. Polymorphisms investigated were the Msp I polymorphism of the $\alpha$$_{2A}$-adrenergic receptor ($\alpha$$_{2A}$-AR) gene, the Mnl I polymorphism of the $\alpha$$_2$-adrenergic receptor ($\alpha$$_2$-AR) gene, the BstO I polymorphism of the $\beta$$_3$-adrenergic receptor ($\beta$$_3$-AR) gene, the Pml I polymorphism of the lamin A/C (LMNA) gene, the Hga I polymorphism of the clearance receptor (NPRC) gene, the Msp I polymorphism of the leptin gene, BclI polymorphism of the uncoupling protein 1 (UCPI) gene and the Hha I polymorphism of the fatty acid binding protein 2 (FABP2) gene. Among these genetic markers, Pml I polymorphism at the LMNA gene and Bcl I polymorphism at the UCP1 gene were significantly associated with obesity. However, further studies are required whether thease findings are reproduced in large population, although two polymorphisms might be useful as genetic markers in the ethiology of obesity in Korean population.ion.

• Korean Journal of Veterinary Research
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• v.33 no.2
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• pp.211-216
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• 1993

To elucidate the action of the cholinergic and ${\alpha}_2$-adrenergic nerve on the isolated ileal smooth muscle of the dog, effect a of electrical field stimulation were investigated on the pretreatment of the physostigmine; cholinestrase inhibitor, yohimbine; ${\alpha}_2$-adrenoceptor blocker, atropine ; cholinergic receptor blocker and phentolamine; non-selective $\alpha$-adrenoceptor blocker from physiograph. 1. The contractile response induced by electrical field stimulation was the frequency (2-40 Hz)-dependent manner. 2. The contractile response induced by electrical field stimulation was markedly increased by the pretreatment of physostigmine$(1{\mu}M)$; cholinestrase inhibitor. 3. The contractile response induced by electrical field stimulation was increased by the pretreatment of yohimbine$(1{\mu}M)$; ${\alpha}_2$-adrenoceptor blocker. These finding suggest that it was powerful excitatory action by cholinergic nerve and inhibitory action by ${\alpha}_2$-adrenergic nerve on ileal smooth muscle of the dog.

• The Korean Journal of Pharmacology
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• v.19 no.1
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• pp.85-92
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• 1983

Intestine is innervated by an interconnected plexus of both sympathetic and parasympathetic nerve fibers. Sympathetic influence causes inhibition of intestinal motility mediated by both ${\alpha}-\;and\;{\beta}-adrenergic$ receptors. The mechanism of intestinal relaxation by ${\beta}-receptors$ has been extensively studied, but the function of ${\alpha}-receptors$ in intestinal motility is still unclear. Although it is suggested that catecholamine reduces acetylcholine release and this may play an important role in ${\alpha}-receptor$ mediated intestinal relaxation, there is no definite evidences about the mechanism and site of action of ${\alpha}-receptor$ mediated relaxation. In this experiment, therefore, the effect and site of action of ${\alpha}-receptor$ agonists were investigated in the guinea pig ileum using electrical field stimulation. The results are summarized as follows : 1) Electrical field stimulation elicited tonic contraction in isolated guinea pig ileum ana this contraction was completely inhibited by the pretreatment of tetrodotoxin or atropine. 2) Norepinephrine, epinephrine and dopamine inhibited the contraction induced by electrical field stimulation but methoxamine and phenylephrine had little effects. 3) Inhibitory effects of norepinephrine and dopamine was partially blocked by yohimbine and phentolamine pretreatment. But haloperidol and propranolol pretreatment cause no effects on the electrical field stimulation induced contraction. Inhibitory effect of dopamine was completely blocked by both haloperidol and yohimbine pretreatment. 4) Inhibitory effects of norepinephrine and dopamine were little affected by the pretreatment with hexamethonium. It is suggested that electrical field stimulation causes tonic contraction of guinea pig ileum by releasing acetylcholine from postganglionic fiber, and this release is blocked by presynaptic ${\alpha}-receptor$ activation.

• The Korean Journal of Pain
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• v.22 no.1
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• pp.21-27
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• 2009

Background: The neuropathic pain arising from nerve injury is difficult to treat and the therapeutic effects of opioid drugs remain debatable. Agonists acting at the ${\alpha}_2$ adrenergic and opioid receptors have analgesic properties and they act synergistically when co-administered in the spinal cord. The lack of subtype-selective pharmacological agents has previously impeded the synergistic effects that are mediated by the adrenergic receptor subtypes. Methods: We created neuropathic pain model by ligating the L5 spinal nerve in Sprague-Dawley rats (n = 18). We divided the rats into three groups (n = 6 for each group), and we administered intraperitoneal morphine (1 mg/kg, 3 mg/kg, 5 mg/kg) and then we measured the mechanical allodynia with using von-Frey filaments for 8 hours. We then injected morphine (5 mg/kg) intraperitoneally, twice a day for 2 weeks. We measured the tactile and cold allodynia in the morphine group (n = 9) and the saline group (n = 9). After 2 weeks, we decapitated the rats and harvested the spinal cords at the level of lumbar enlargement. We compared the ${\alpha}_2$ subtype mRNA expression with that of control group (n = 6) by performing real time polymerase chain reaction (RTPCR). Results: Intraperitoneal morphine reduced the neuropathic pain behavior in the dose-dependent manner. Chronic morphine administration showed an antiallodynic effect on the neuropathic pain rat model. The rats did not display tolerance or hyperalgesia. The expression of the mRNAs of the ${\alpha}_{2A}$, ${\alpha}_{2B}$, ${\alpha}_{2C}$ subtypes decreased, and morphine attenuated this effect. But we could not get statistically proven results. Conclusions: Systemic administration of morphine can attenuate allodynia during both the short-term and long-term time course. Morphine has an influence on the expression of ${\alpha}_2$ receptor subtype mRNA. Yet we need more research to determine the precise effect of morphine on the ${\alpha}_2$ subtype gene expression.

• Korean Journal of Veterinary Research
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• v.33 no.4
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• pp.617-622
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• 1993

The preliminary studies on the localization of adrenoceptors were performed on smooth muscle strips of bovine esophageal groove. The mechanical activity of the muscle strip was recorded isometrically in vitro.w In the bottom circular muscle strips. the excitatory ${\alpha}-adrenergic$ responses were not blocked by tetrodotoxin$(2.1{\times}10^{-6}M)$ and denervation which was carried by cold storage of strips for 48 hrs in Tyrode's solution at $5-6{^{\circ}C}$ without oxygen supply. These excitatory ${\alpha}-adrenergic$ responses were partially blocked by atropine. In the lip longitudinal muscle strips, the inhibitory${\beta}-adrenergic$ responses were not blocked by pretreatment of tetrodotoxin and atropine. The results suggest that ${\beta}-adrenergic$ receptors mediating relaxations are located on the postsynaptic smooth muscle cells, whereas ${\beta}-adrenergic$ receptors mediating contractions are located both in the smooth muscle cells and in the cholinergic neurones.

• Korean Journal of Veterinary Research
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• v.27 no.2
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• pp.201-206
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• 1987

This study was carried out to investigate the action of ATP, which has been known as the neurotransmitter of noncholinergic- and nonadrenergic-nerve, on the motility of immature pig uterine smooth muscle. The results were summarized as follows; 1. The contraction and the contractile responses caused by ATP were increased in a dose-dependent manner between the concentration of ATP $10^{-6}M$ and $10^{-3}M$. The maximal contractile effect was appeared at the concentration of ATP $10^{-3}M$ and it was 70.2% of 100mM K contraction. 2. The contractile responses induced by ATP ($10^{-4}M$) were not blocked by the pretreatment with cholinergic receptor blocker, atropine ($10^{-6}M$). 3. The contractile responses induced by ATP ($10^{-4}M$) were not blocked by pretreatment with ${\alpha}$-adrenergic receptor blocker, phentolamine ($10^{-6}M$) and ${\beta}$-adrenergic receptor blocker, propranolol ($10^{-6}M$). 4. The contractile response induced by ATP ($10^{-4}M$) was not blocked by the pretreatment with $H_1-receptor$ blocker, pyrilamine ($10^{-6}M$) and $H_2-receptor$ blocker, cimetidine ($10^{-6}M$).

• The Korean Journal of Pain
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• v.9 no.2
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• pp.318-325
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• 1996

Background: Sympathectomy relieves pain in sympathectically maintained pain, and subcutaneous injection of norepinephrine(NE) can rekindle mechanical allodynia. However, the mechanism of rekindling is not clear. The purpose of this study is to investigate which subtype of $\alpha$-adrenoceptor is involved in NE-induced rekindling of mechanical allodynia in sympathectomized neuropathic rats. Methods: Neuropathic injury was produced by tightly ligating the left L5 and L6 spinal nerves of 36 male Sprague-Dawley rats and bilateral lumbar sympathectomy was done at two weeks postoperatively. Starting at 7 days after sympathectomy, rekindling of mechanical allodynia was induced by NE and clonidine injected into the left paw, which was reversed by pretreatment of phentolamine and idazoxan. Mechanical allocynia was quantified by measuring the frequency of foot lifts to two von Frey filaments applied to the paw. Results: All tested rats displayed well-developed signs of mechanical allodynia at the left paw that were abolished by a bilateral lumbar sympathectomy. Subcutaneous (s.c.) injection of NE (0.05 ${\mu}g$) into the affected paw of sympathectomized neuropathic rats rekindled previous mechanical allodynia. These effects could be mimicked by an ${\alpha}_2$-receptor agonist clonidine, but not by an ${\alpha}_1$-receptor agonist phenylephrine. The NE-induced rekindling of mechanical allodynia was significantly reduced by prior s.c. injection of a mixed $\alpha$-receptor antagonist phentolamine (20${\mu}g$) and ${\alpha}_2$-receptor antagonist idazoxan(20${\mu}g$), but not by a ${\alpha}_1$-receptor antagonist terazosin (20${\mu}g$). The pretreatment of idazoxan produced dose-related inhibition of NE-induced rekindling of mechanical allodynia. The rekindling induced by ${\alpha}_2$-receptor agonist clonidine (5${\mu}g$) was also reversed by prior s.c. injection of ${\alpha}_2$-receptor antagonist idazoxan (20${\mu}g$). Conclusion: Subcutaneous injection of NE into the paw of sympathectomized neuropathic rats rekindles mechanical allodynia, which is reversed by an ${\alpha}_2$-, but not by an ${\alpha}_1$-receptor antagonist. Therefore, rekindling of mechanical allodynia in sympathectomized neuropathic rats is mediated by ${\alpha}_2$-adrenoceptor.

• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.493-500
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• 1994

The purpose of this study was to investigate the effects of neurotransmitters and the source of $Ca^{2+}$ in the effects of neurotransmitters on the motility of pig oviductal isthmic smooth muscle. The motility of the isolated smooth muscle was recorded by using physiological recording system. The results were summarized as follows; Acetylcholine, norepinephrine, histamine and prostaglandin $F_{2{\alpha}}(PGF_{2{\alpha}})$ caused the contraction and the contractile responses were increased in a dose-dependent manner from the concentration of $10^{-7}$ to $10^{-4}M$. The maximum contractility of acetylcholine, norepinephrine, histamine and $PGF_{2{\alpha}}$ was 65.99, 28.66, 83.99 and 47.33% of 100 mM K contraction, respectively. The contractile response induced by acetylcholine$(10^{-6}M)$ was completely blocked by the pretreatment with cholinergic receptor blocker, atropine$(10^{-6}M)$, the contractile response induced by norepinephrine$(10^{-5}M)$ was blocked by the pretreatment with ${\alpha}$-adrenergic receptor blocker, phentolamine$(10^{-6}M)$ but was not blocked and rather increased by the pretreatment with ${\beta}$-adrenergic receptor blocker. propranolol$(10^{-6}M)$, the contractile response induced by histamine$(10^{-6}M)$ was completely blocked by the pretreatment with $H_1$-histaminergic receptor blocker, pyrilamine$(10^{-6}M)$ but was increased by the pretreatment with $H_2$-histaminergic receptor blocker, cimetidine$(10^{-6}M)$. The contractile response induced by acetylcholine$(10^{-6}M)$, norepinephrine$(10^{-5}M)$ and histamine$(10^{-6}M)$ was weakly contracted response in $Ca^{2+}$-free medium, but the contractile response induced by $PGF_{2{\alpha}}(10^{-6}M)$ was disappeared. The contractile response induced by acetylcholine$(10^{-6}M)$, norepinephrine$(10^{-5}M)$ and histamine$(10^{-6}M)$ was powerfully depressed by the pretreatment with $Ca^{2+}$-channel blocker, verapamil$(10^{-5}M)$ but the contractile response induced by $PGF_{2{\alpha}}(10^{-6}M)$ was completely inhibited.

• YAKHAK HOEJI
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• v.45 no.1
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• pp.85-92
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• 2001

Nitric oxide is a tonically produced vasodilator that maintains blood pressure in the normal animal. The chronic inhibition of nitric oxide synthase (NOS) elicits the hypertension in rats. However, the mechanism of hypertension induced by chronic inhibition of NOS is not clear. Thus, to clarify the mechanism of the occurance of hypertension, the changes in $\alpha$-adrenergic systems in rats treated with NOS inhibitors for 21 days were examined. Chronic administration of L-NAME significantly increased in the basal blood pressure, but chronic administration of 7-nitroindazole did not. Phenylephrine and G-protein stimulator elicited the more potent contraction in the aorta of the L-NAME-induced hypertensive rats. However when the contractile responses by phenylephrine and G-protein stimulator were calculated the proportion to the contraction by 25 mM KCL, there was no difference between the vehicle-treated rats and the L-NAME-treated rats. The density of $\alpha$-adrenergic receptors in aortic tissue was not changed by the chronic inhibition of NOS. These results suggest that hypertension induced by chronic inhibition of NOS is due to the inhibition of eNOS and the increased responses to the adrenergic drugs are due to the changes of the intracellular contactile mechanism of aortic tissue rather than the changes of receptor density.

• The Korean Journal of Pain
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• v.12 no.2
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• pp.177-182
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• 1999

Background: Clonidine, an ${\alpha}_2$ adrenergic agonist blocks nerve conduction. However, in our previous experiment we found that adrenaline neither blocks nerve conduction by itself nor augment nerve conduction blockade by lidocaine near clinical concentrations. Possible explanations are: 1) there may be antagonism between some of adrenergic receptors, 2) clonidine may block nerve conduction via non-adrenergic mechanism. The purpose of this study is to obtain dose-response curves of several different forms of adrenergic receptor agonist to see the relative potencies of each adrenergic receptors to block nerve conduction. Methods: Recordings of compound action potentials of A-fiber components (A-CAPs) were obtained from isolated sciatic nerves of adult male Sprague-Dawley rats. Nerve sheath of the sciatic nerve was removed and desheathed nerve bundle was mounted on a recording chamber. Single pulse stimuli (0.5 msec, supramaximal stimuli) were repeatedly applied (2Hz) to one end of the nerve and recordings of A-CAPs were made on the other end of the nerve. Dose-response curves of epinephrine, phenylephrine, isoproterenol, clonidine were obtained. Results: $ED_{50}$ of each adrenergic agonist was: $4.51\times10^{-2}$ M for epinephrine; phenylephrine, $7.74\times10^{-2}$ M; isoproterenol, $9.61\times10^{-2}$ M; clonidine, $1.57\times10^{-3}$ M. Conclusion: This study showed that only clonidine, ${\alpha}_2$ adrenergic agonist, showed some nerve blocking action while other adrenergic agonists showed similar poor degree of nerve blockade. This data suggest that non-effectiveness of epinephrine in blocking nerve conduction is not from the antagonism between adrenergic receptors.