• The Korean Journal of Physiology
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• v.27 no.2
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• pp.217-225
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• 1993

The role of endogenous brain angiotensin ll (Ang ll) in mediating the cardiovascular and vasopressin responses to hemorrhage was assessed in conscious spontaneously hypertensive rats (SHR), and normotensive Wistar-Kyoto (WKY) rats. Artificial cerebrospinal fluid (aCSF) with or without losartan (DuP 753), a specific Ang ll receptor subtype I $(AT_1)$ antagonist and saralasin, a combined $AT_1/AT_2$ antagonist was administered into the cerebral lateral ventricle. Hemorrhage was performed at a rate of 3 ml/kg/min far 5 min. Intracerebroventricular administration of losartan and saralasin had no effect on the basal blood pressure. However, in response to acute hemorrhage, central Ang ll antagonists produced a remarkably greater fall in blood pressure, a reduced tachycardia, and an enhanced renin release compared with the aCSF control experiment in SHR, but effected no significant change in WKY rats. Central Ang ll-blocked SHR showed significantly lower blood pressure and heart rate during the recovery period than the aCSF control rats. Vasopressin release tallowing the hemorrhage was attenuated by icv Ang ll antagonists: the effect was more pronounced in SHR than in WKY rats. Centrally administered losartan and saralasin produced remarkably similar effects on the cardiovascular function and vasopressin responses to hemorrhage. These data suggest that brain Ang ll acting primarily through AT, receptors plays an important physiological role in mediating rapid cardiovascular regulation and vasopressin release in response to hemorrhage especially in Hypertensive rats.

• The Korean Journal of Physiology
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• v.19 no.1
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• pp.35-48
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• 1985

One of most frequently used anesthetic agents is barbiturate derivatives. Pentobarbital or thiopental sodium have been used most frequently in the laboratory or clinical practice. There have been reports on the renal effects of barbiturate anesthesia in human and laboartory animals. Renal effects of thiopental sodium anesthesia, however, are still controversial. One of the discrepancies may be derived from the doses used. It has been reported that subanesthetic small dose of thiopental sodium influences the renal function directly. To clarify possible central effects of very small amounts of thiopental sodium on the renal function, experiments have been done in conscious rabbits. Thiopental sodium was infused into the lateral cerebroventricle for 10 minutes. Intracerebroventricular thiopental sodium induced increased urinary volume, glomerular filtration rate and renal plasma flow by doses of $0.1{\sim}1.0\;mg/10 min/rabbit$. Filtration fractions were not changed. Sodium, chloride and potassium excretions were increased by 0.065 mg/10 min/rabbit of thiopental sodium without significant changes of renal hemodynamics. Higher doses of thiopental sodium $(0.1{\sim}1.0\;mg/10 min/rabbit)$ induced greater increases of electrolytes excretion and renal hemodynamics. Free water clearance was not changed by thiopental sodium, but the fractional excretion of free water showed a tendency of decrease. Fractional excretion of sodium was increased by doses of 0.065 to 1.0 mg of thiopental sodium . Highly significant correlation between the changes of glomerular filtration rate and the changes of sodium excretion were found in the higher doses. Plasma renin concentration (activity) was not changed by the centrally administered thiopental sodium. Intravenous thiopental sodium, 1.0 mg/rabbit, induced no changes of renal function in conscious rabbit. These data suggest that intracerebroyentricular thiopental sodium can increase urinary sodium excretion directly by inhibition of sodium reabsorption in the renal tubules and/or indirectly by increasing the renal hemodynamics.

• Korean Journal of Biological Psychiatry
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• v.19 no.4
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• pp.187-192
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• 2012

Objectives Although antipsychotic drug clozapine has superior efficacy, this is hampered by metabolic side effects such as weight gain and diabetes. Recent studies demonstrate that clozapine induces insulin resistance. However, the identity and location of insulin resistance induced by clozapine has not been clarified. In this study, the effect of clozapine on central insulin response was investigated in rats. Methods Male Sprague-Dawley rats received intraperitoneal injection of clozapine or vehicle, which was followed by intracerebroventricular injection of insulin or its vehicle. The effects of clozapine on insulin-induced changes in blood glucose level and Akt phosphorylation in hypothalamus were investigated. Results Intraperitoneal injection of clozapine (20 mg/kg) increased blood glucose in rats. Intracerebroventricular injection of insulin reduced blood glucose in rats, which was blunted by pretreatment of clozapine. Accompanied with the antagonistic effect of clozapine to central insulin action in terms of blood glucose, clozapine inhibited the insulin-induced phosphorylation of Akt at Ser473 in rat hypothalamus. Conclusion Administration of clozapine inhibited the central insulin-induced changes in blood glucose and Akt phosphorylation in rat hypothalamus. These findings suggest that hypothalamus could be the site of action for the clozapine-induced insulin resistance.

• Development and Reproduction
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• v.14 no.1
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• pp.35-41
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• 2010

Mammalian reproduction is regulated by a feedback circuit of the key reproductive hormones such as GnRH, gonadotropin and sex steroids on the hypothalamic-pituitary-gonadal axis. In particular, the onset of female puberty is triggered by gain of a pulsatile pattern and increment of GnRH secretion from hypothalamus. Previous studies including our own clearly demonstrated that genistein (GS), a phytoestrogenic isoflavone, altered the timing of puberty onset in female rats. However, the brain-specific actions of GS in female rats has not been explored yet. The present study was performed to examine the changes in the activities of GnRH neurons and their neural circuits by GS in female rats. Concerning the drug delivery route, intracerebroventricular (ICV) injection technique was employed to eliminate the unwanted actions on the extrabrain tissues which can be occurred if the testing drug is systemically administered. Adult female rats (PND 100, 210-230 g BW) were anaesthetized, treated with single dose of GS ($3.4{\mu}g$/animal), and sacrificed at 3 hrs post-injection. To determine the transcriptional changes of reproductive hormone-related genes in hypothalamus, total RNAs were extracted and applied to the semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). ICV infusion of GS significantly raised the transcriptional activities of enhanced at puberty1 (EAP-1, p<0.05), glutamic acid decarboxylase (GAD67, p<0.01) which are known to modulate GnRH secretion in the hypothalamus. However, GS infusion could not change the mRNA level of nitric oxide synthase 2 (NOS-2). GS administration significantly increased the mRNA levels of KiSS-1 (p<0.001), GPR54 (p<0.001), and GnRH (p<0.01) in the hypothalami, but decreased the mRNA levels of LH-$\beta$ (p<0.01) and FSH-$\beta$ (p<0.05) in the pituitaries. Taken together, the present study indicated that the acute exposure to GS could directly activate the hypothalamic GnRH modulating system, suggesting the GS's disrupting effects such as the early onset of puberty in immature female rats might be derived from premature activation of key reproduction related genes in hypothalamus-pituitary neuroendocrine circuit.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.3
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• pp.149-154
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• 2002

The blood pressure (BP) is regulated by the nervous system and humoral factors, such as renin- angiotensin system, vasopressin and others. In the present study, we examined the central effects of glutamate and GABA on the cardiovascular regulation by injection of these substances into the lateral ventricle and also investigated the relationship between these central effects and the action of angiotensin II (Ang). Male Sprague Dawley rats, $350{\sim}400$ g, were anesthetized with urethane and instrumented with an arterial catheter for direct measurement of BP and heart rate (HR), and an guide cannula in the lateral ventricle for drug injection. A glass microelectode was inserted into the rostral ventrolateral medulla (RVLM) for recording single unit spikes. Barosensitive neurons were identified by changes of single unit spikes in RVLM following intravenous injection of nitroprusside and phenylephrine. The effects of GABA and glutamate injected into the lateral ventricle were studied in single neuronal activity of the RVLM in addition to changes in BP and heart rate, and compared the results before and after treatment with intravenous losartan, nonpeptide Ang II-type 1 receptor antagonist (1 mg/100 g BW). Intracerebroventricular administration of GABA decreased systolic blood pressure (SBP) and HR, but increased the firing rates in the RVLM. However, intracerebroventricular glutamate injection produced effects opposite to GABA. After pretreatment of intravenous losartan, the central effects of GABA on BP and firing rate in the RVLM were significantly attenuated and that of glutamate showed a tendency of attenuation. These results suggested that central GABA and glutamate regulated BP and firing rates in RVLM were inversely related to BP change. The central effects of GABA or glutamate on the autonomic nervous function were modulated by humoral factor, Ang II, by maintaining BP.

• The Korean Journal of Pain
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• v.14 no.2
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• pp.225-230
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• 2001

Background: Opioids such as morphine are widely used in the treatment for pain, but chronic treatment with morphine can be complicated by the development of tolerance. The mechnisms of tolerance were still not completely understood, but recently it has been reported that NOS inhibitors can prevent development of morphine tolerance in animals. The present study accessed the possible role of supraspinal NO on antinociceptive effect of morphine in morphine tolerance using a highly specific inhibitor of the neuronal isoform of NOS, 1-(2-trifluoromethylphenyl) imidazole (TRIM). Methods: Thirty two male SD rats (300 g) were prepared with intracerebroventricular (icv) and IV cannulae. We administrated IV morphine, 3 mg/kg, daily for 4 days, resulting in tolerance. On the fifth day, a challenge dose of morphine, 3 mg/kg, was administered following pretreatment with icv TRIM, $10{\mu}g$. We also evaluated the antinociceptive effect of icv TRIM alone and the effect on a single dose of morphine (3 mg/kg) in morphine nave rats. Antinociception from morphine was determined by response to intraplantar injection of 5% formalin $100{\mu}l$ was qualified as the number of flinches in the first 0-10 min (first phase), 10-40 min Phase IIa, and 40-60 min (Phase IIb). Results: Pretreatment with icv TRIM significantly enhanced the antinociceptive effects of systemically administered morphine in morphine tolerant rats. The antinociceptive effect of morphine in opioid nave rats was also significantly increased by pretreatment with icv TRIM. Conclusions: Our results further support the hypothesis that supraspinal NO modulates morphine-sensitive nociceptive process in morphine tolerance due to chronic intravenous administration.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.4
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• pp.225-233
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• 2002

Kanagawa hemolysin (KH), an exotoxin produced from Kanagawa phenomenon-positive Vibrio parahemolyticus, has been shown to possess various biological activities including hemolysis, enterotoxicity, cytotoxicity, and cardiotoxicity. The aim of this study was to investigate the effect of KH on the cardiovascular system and its mechanism, employing in vivo and in vitro experiments of the rat. Intracerebroventricular (icv) administration of 100 mHU KH produced a marked and continuous pressor effect (icv KH-pressor effect), and the icv pressor effect was not repeatable. However, intravenous (iv) injection of the same dose of KH induced a prominent depressor effect (iv KH-depressor effect). The icv KH-pressor effect was inhibited by acid-denaturation, while the iv KH-depressor effect was not. Simultaneous icv administration of the three agents (ouabain, diltiazem, or bumetanide: $10{\mu}g/kg$ each) significantly reduced the pressor effect. The icv KH-pressor effect was inhibited by treatment with iv phentolamine or chlorisondamine, but was not affected by iv candesartan. The iv KH-depressor effect was repeatable and was attenuated by treatment with iv NAME or methylene blue. In vitro experiments using isolated thoracic aorta, $10^{-6}$ M phenylephrine (PE) and 50 mM KCl produced a sustained contraction. In rings contracted with either agents, KH showed relaxant responses in a concentration- dependent fashion and the relaxation (KH-vasorelaxation) was not dependent on the existence of the endothelium. The KH-vasorelaxation in the endothelium-intact rings contracted by PE was abolished by methylene blue treatment. In summary, the present findings suggest that in the icv KH-pressor effect the cation leak-inducing action of KH is implicated, which leads to the increased central sympathetic tone, that the iv KH-depressor effect results from the vasorelaxation via NO-guanylate cyclase system, and that the KH-vasorelaxation is independent of the endothelium and the guanylate cyclase system is involved in it. In conclusion, the mechanism of KH producing the icv pressor effect may not be identical to that of KH producing the iv depressor effect.

• Animal Bioscience
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• v.35 no.12
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• pp.1904-1910
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• 2022

Objective: This study aimed to investigate the effects of corticotropin-releasing factor (CRF) on the feed intake of broiler chickens and explore its influencing mechanism. Methods: The study included two trials. In trial 1, 32 male broiler chickens (Arbor Acres, Gallus gallus domesticus) were given ventricle buried tubes, and they were allowed to recover for 3 days. At 8:00 AM, intracerebroventricular (ICV) injection with CRF or normal saline was performed in 10-day-old broiler chickens, which were divided into the 5, 10, and 20 ㎍ and control (normal saline) groups according to the dose of CRF injection. In trial 2, chickens were divided into the 10 ㎍ and control group (physiological saline) to repeat trial 1. Results: Results of trial 1 showed that the cumulative amount of feed intake in the 10 or 20 ㎍ groups was considerably lower than that of the control group after ICV injection with CRF. The lowest amount of feed intake was obtained with the addition of 10 ㎍ of CRF. In trial 2, the expression of ghrelin in the hypothalamus injected with 10 ㎍ of CRF increased significantly, but the expression of ghrelin in various sections of the small intestine considerably decreased. The expression of CRF receptor subtypes 1 (CRFR1) in the hypothalamus and some parts of the small intestine remarkably increased, and the expression of CRF receptor subtypes 2 (CRFR2) increased only in the duodenum, whereas the expression of growth hormone secretagogue receptor (GHSR-1α) in the jejunum and ileum increased considerably after ICV injection of 10 ㎍ of CRF. Conclusion: The CRF at 10 ㎍ increased ghrelin expression in the hypothalamus and CRFR1 expression in the small intestine, and this phenomenon was related to the suppressed feed intake of broiler chickens.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.303-303
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• 1994

ICV infusion of morphine (MOR) produces strong analgesia in man and animals. The analgesic effect is thought to be mediated by the centrifugal inhibtory control, But neural mechanisms of the analgesic effect of ICV morphine are not well understood. For example, in the previous studies, ICV morphine does not inhibit nociceptive transmission in the spinal cord. On the contrary, ICV MOR often excites activity of dorsal horn neuron in the spinal cord. In the present study, we found that ICV MOR had dust actions on activity of dorsal horn neuron that it produced both inhibition and excitation of dorsal horn neurons. Since MOR exerts i Is action via three different types of opioid receptors, we further sought to investigate if there are differential effects of opioid receptor agonists on dorsal horn neurons when administered ICV.

• Journal of Ginseng Research
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• v.16 no.1
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• pp.13-17
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• 1992

The present experiments were performed to investigate the effects of the ginseng total saponin on the development of physical dependence on morphine via intracerebroventricular (i.c.v) route. Morphine (10 $\mu\textrm{g}$/${mu}ell$/hr) was continuously infused via osmotic minipumps into lateral cerebral ventricle of male Sprague Dawley rats for 7 days. Concurrent ginseng total saponin (100, 200 $\mu\textrm{g}$/10${mu}ell$/hr) was infused intraperitoneally (i.p) via osmotic pumps for 7 days. Treatment with ginseng total saponin (200$\mu\textrm{g}$/10${mu}ell$/hr) significantly diminished jumping, teeth chattering, hypothermia and weight loss precipitated by naloxone, compared with those animals received only morphine infusion. These results suggest that ginseng total saponin has central effect on the inhibition of physical dependence on morphine, as systemic ginseng total saponin inhibits the development of physical dependence in rats infused with morphine intracerebroventricularly.