• Toxicological Research
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• 제17권
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• pp.47-57
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• 2001

Alzheimer's disease (AD) is the most common cause of dementia in the elderly, and its pathology is characterized by the presence of numerous numbers of senile plaques and neurofibrillary tangles. Several genetic and transgenic studies have indicated that excess amount of $\beta$-amyloid protein (A$\beta$) is produced by mutations of $\beta$TEX>$\beta$-amyloid precursor protein and causes learning impairment. Moreover, $A\beta$ has a toxic effect on cultured nerve cells. To prepare AD model animals, we have examined continuous (2 weeks) infusion of $A\beta$ into the cerebral ventricle of rats. Continuous infusion of $A\beta$ induces learning impairment in water maze and passive avoidance tasks, and decreases choline acetyltransferase activity in the frontal cortex and hippocampus. Immunohistochemical analysis revealed diffuse depositions of $A\beta$ in the cerebral cortex and hippocampus around the ventricle. Furthermore, the nicotine-evoked release of acetylcholine and dopamine in the frontal cortex/hippocampus and striatum, respectively, is decreased in the $A\beta$-infused group. Perfusion of nicotine (50 $\mu\textrm{M}$) reduced the amplitude of electrically evoked population spikes in the CA1 pyramidal cells of the control group, but not in those of the $A\beta$-infused group, suggesting the impairment of nicotinic signaling in the $A\beta$-infused group. In fact, Kd, but not Bmax, values for ［$^3H$］ cytisine binding in the hippocampus significantly increased in the $A\beta$-infused rats. suggesting the decrease in affinity of nicotinic acetylcholine receptors. Long-term potentiation (LTP) induced by tetanic stimulations in CA1 pyramidal cells, which is thought to be an essential mechanism underlying learning and memory, was readily observed in the control group, whereas it was impaired in the $A\beta$-infused group. Taken together, these results suggest that $A\beta$ infusion impairs the signal transduction mechanisms via nicotinic acetylcholine receptors. This dysfunction may be responsible, at least in part, for the impairment of LTP induction and may lead to learning and memory impairment. We also found the reduction of glutathione- and Mn-superoxide dismutase-like immunoreactivity in the brains of $A\beta$-infused rats. Administration of antioxidants or nootropics alleviated learning and memory impairment induced by $A\beta$ infusion. We believe that investigation of currently available transgenic and non-transgenic animal models for AD will help to clarify the pathogenic mechanisms and allow assessment of new therapeutic strategies.

• 생물정신의학
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• 제23권3호
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• pp.108-115
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• 2016

Aggression and aggressive behaviors, often explained as harmful social interaction with the intention of hurting or inflicting damage upon another, have been considered as an adaptive mechanism from the evolutionary psychological point of view. However, various studies on aggression and aggressive behaviors have been done with psychopathological approach as the extreme aggressive behaviors may harm themselves and others at the same time. Recently, researchers have attempted to explain aggression in terms of neurobiological substrates rather than based on traditional psychopathological and/or behavioral concept. In this regard, there have been findings of differences in neurotransmitters and their receptors, and genetic polymorphisms. In this review article, we provide a brief overview of the literature about seven most frequently reported neurotransmitters including neurohormones (serotonin, norepinephrine, dopamine, gamma-aminobutyric acid, nitric oxide, oxytocin and vasopressin) and an associated enzyme (monoamine oxidase A), which are known to be related with aggression and aggressive behaviors.

• Advances in Traditional Medicine
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• 제3권2호
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• pp.100-105
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• 2003

Systematic analysis of caffeine from the commercial samples of Indian tea leaves was performed by a routine method and the content of caffeine was found to be 19.0-37.4 mg/100 g leaves. The caffeine contents from coffee seeds and chicory from Indian origin were analyzed and found to be 0.6540-1.4920 g/100 g seeds. Caffeine contents of roasted Indian chicory roots were lower than either those of Indian tea leaves or Indian coffee seeds. The multidrug resistance (MDR) reversing effects were tested on a mouse leukemia cell line of L-5178 cells by methanol extracts [M1-M15] of Indian tea leaves and coffee seeds, comparing to a control of $({\pm})-verapamil$. The effects were measured by fluorescence ratio between treated and untreated group cells. Among fifteen methanol extracts, a Gemini tea [M6] (fluorescence activity ratio 5.26) had the most potent effect for L-5178 cells. The extract M6 was 0.63-fold of $({\pm})-verapamil$. We suggest that one of mechanisms of reversal by M6 might have strong affinity to dopamine $D_1$ and D_2$ receptors. Further studies with many more tumor and normal cell lines are necessary to confirm the MDR reversal specificity of coffee methanol extracts.

• 대한수의학회지
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• 제39권3호
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• pp.463-471
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• 1999

Magnesium($Mg^{2+}$) is one of the most abundant intracellular divalent cation. Although recent studies demonstrate that adrenergic receptor stimulation evokes marked changes in $Mg^{2+}$ homeostasis, the regulation of $Mg^{2+}$ by dopaminergic receptor stimulation is not yet known. In this work, we used dopaminergic agents to identify which type(s) of receptors were involved in the mobilization of $Mg^{2+}$ by dopaminergic receptor stimulation in the perfused rat hearts, isolated myocytes and circulating blood. The $Mg^{2+}$ content was measured by atomic absorbance spectrophotometry. Dopamine(DA), apomorphine(APO) and pergolide stimulated $Mg^{2+}$ efflux in the perfused rat hearts and these effects were inhibited by haloperidol or fluphenazine, nonselective dopaminergic antagonists. SKF38393, a selective doparminergic agonist, increased $Mg^{2+}$ efflux from the perfused hearts in dose dependant manners and SKF38393-induced $Mg^{2+}$ efflux was blocked by haloperidol. However, dopaminergic agonists-induced $Mg^{2+}$ efflux was potentiated in the presence of sulpiride or eticlopride, $D_2$-selective antagonist, from the perfused hearts. This increase of $Mg^{2+}$ efflux was blocked by haloperidol or imipramine. DA or pergolide increased in circulating $Mg^{2+}$ from blood. By contrast, PPHT stimulated $Mg^{2+}$ influx(a decrease in efflux) from the perfused hearts and circulating blood. PPHT-induced $Mg^{2+}$ influx was blocked by fluphenazine in the perfused hearts. DA-stimulated $Mg^{2+}$ efflux was inhibited by dopaminergic antagoinst in the isolated myocytes. In conclusion, the flux of $Mg^{2+}$ is modulated by DA receptor activation in the rat hearts. The efflux of $Mg^{2+}$ can be increased by $D_1$-receptor stimulation and decreased by $D_2$-receptor stimulation, respectively.

• The Korean Journal of Physiology and Pharmacology
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• 제24권6호
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• pp.545-553
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• 2020

Aripiprazole is a quinolinone derivative approved as an atypical antipsychotic drug for the treatment of schizophrenia and bipolar disorder. It acts as with partial agonist activities at the dopamine D2 receptors. Although it is known to be relatively safe for patients with cardiac ailments, less is known about the effect of aripiprazole on voltage-gated ion channels such as transient A-type K⁺ channels, which are important for the repolarization of cardiac and neuronal action potentials. Here, we investigated the effects of aripiprazole on Kv1.4 currents expressed in HEK293 cells using a whole-cell patch-clamp technique. Aripiprazole blocked Kv1.4 channels in a concentration-dependent manner with an IC₅₀ value of 4.4 μM and a Hill coefficient of 2.5. Aripiprazole also accelerated the activation (time-to-peak) and inactivation kinetics. Aripiprazole induced a voltage-dependent (δ = 0.17) inhibition, which was use-dependent with successive pulses on Kv1.4 currents without altering the time course of recovery from inactivation. Dehydroaripiprazole, an active metabolite of aripiprazole, inhibited Kv1.4 with an IC₅₀ value of 6.3 μM (p < 0.05 compared with aripiprazole) with a Hill coefficient of 2.0. Furthermore, aripiprazole inhibited Kv4.3 currents to a similar extent in a concentration-dependent manner with an IC₅₀ value of 4.9 μM and a Hill coefficient of 2.3. Thus, our results indicate that aripiprazole blocked Kv1.4 by preferentially binding to the open state of the channels.

• 대한약리학회지
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• 제22권2호
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• pp.79-87
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• 1986

중추 dopamine(DA)계가 신장기능 조절에 관여하고 있으며 뇌실내로 DA를 투여하면 norepinephrine(NE)처럼 항이뇨와 항Na 배설을 초래함이 보고된 바 있고, 중추 DA작용에 있어서 adrenergic system이 관여한다는 많은 시사가 있다. 따라서 본 연구에서는alpha-2 adrenocopter 차단제인 yohimbine이 측뇌실내 DA의 신장작용에 어떠한 영향을 미치는가를 관찰하였다. Yohimbine $100\;{\mu}g/kg$을 가토측뇌실내로 투여시(icv) 신혈류 및 사구체 여과율의 감소와 함께 현저한 항이뇨 및 Na 배설감소를 초래하였으며, DA $15\;{\mu}g/kg$ icv 역시 항이뇨를 초래하였으나 yohimbine 전 처치후에는 뇨량 및 Na배설의 증가를 초래하였다. 양을 더올려 $150\;{\mu}g/kg$의 DA를 yohimbine 전처치 가토에 투여하면 3배 이상의 Na배설 증가와 함께 현저한 이뇨작용이 나타났으며 이 작용은 약 20분간 지속되었다. 이때 신혈류 역학은 일부 개선되었다. 다른 DA agonist인 apomorphine은 $100\;{\mu}g/kg$ icv로 현저한 이뇨와 Na 배설증가를 나타내며 신혈류역학도 개선하였으나, yohimbine은 이같은 apomoiphine작용을 차단하지 못하였다. NE $10\;{\mu}g/kg$ icv도 항이뇨 작용을 나타냈으나 yohimbine 전처치에 의하여 차단되지 아니하였다. 이 연구결과로, 중추 DA의 신장작용은 NE처럼 단순하지 않고, 이뇨작용은 신혈류역학의 감퇴에 기인한 항이노작용에 의해 은폐되어 있으며, yohimbine은 DA의 항이뇨작용은 차단하나 이뇨작용에는 영향을 미치지 못하며, DA의 항이뇨작용이 지양될때에만 이뇨작용이 발현됨을 알 수 있었다. 또한 중추를 통한 DA의 신장작용에는 adrenergic system이 관여하지 않은 것으로 보인다.

• 생물정신의학
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• 제2권1호
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• pp.63-69
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• 1995

흰쥐에 항정신병약물인 haloperidol과 sulpiride를 장기간 투여한 뒤 줄무늬체와 후결절조직에서의 DA 수용체 의 변동에 대해 조사하였다. 이와 함께 apomorphine 투여에 따른 상동행동점수도 평가하였다. 흰쥐에 haloperidol(0.5mg/kg/day) 이나 sulpiride(40mg/kg/day)를 4주간 투여하고, 3일간의 약물 배설기간을 거친 후에 apomorphine(0.5mg/kg)을 투여하여 상동행동점수를 평가하였다. Haloperidol을 투여한 군에서는 대조군이나 sulpiride를 투여한 군에 비하여 상동행동에 대한 접수가 높게 나타났고, sulpiride를 투여한 군에서는 대조군과 유사한 정도의 상동행동을 나타내었다. 한편 줄무늬체 조직의 [$^3H$]spiperone의 결합에 대한 포화실험에서는 대조군에 비해 haloperidol이나 sulpiride를 투여한 군에서 최대결합치가 유의하게 증가되었다. 해리상수는 sulpiride투여시 줄무늬체에서 유의하게 감소되어 있었다. Sulpiride를 투여했을때 haloperidol 투여 시와 마찬가지의 DA수용체의 증식이 일어나지만, sulpiride 투여군에서만 상통행동 접수가 낮은 것으로 볼 때, 뇌의 DA계에서 sulpiride가 haloperidol과는 다르게 작용한다는 것을 간접적으로 시사하고 있다. 후결절에서는 sulpiride와 haloperidol을 투여한 양군에서 모두 최대결합치가 현저하게 증가되어 있었다. 또한 해라상수도 양군의 후결절에서 유의하게 증가되었다. 더욱이, 대조군은 후결절에서의 해리상수가 37.5pM, 줄무늬체에서는 86.2pM로 나타나, 후결절에서 줄무늬체에서보다 친화도가 두배 이상 높게 측정되었다. 위의 결과로 미루어 볼 때 sulpiride는 후결절에서 DA수용체의 증식을 유도할 뿐만 아니라 높은 친화력을 가진 몇몇 DA수용체 아형과도 상호작용을 한다는 것을 나타낸다. 또한 대조군에서 줄무늬체와 후결절에서의 친화도가 다른 점은, [$^3H$]spiperone에 반응한 DA수용체 아형은 줄무늬체와 후결절에서 각기 다르다는 점을 시사하고 있다.

• 대한약리학회지
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• 제30권1호
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• pp.87-100
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• 1994

도파민 함유세포가 교감신경절에 존재하는 것으로 알려져 있으나, 말초에서 신경전달 물질로써 그의 역할과 작용기전에 대해서 아직까지 알려진 바가 많지 않다. 따라서 본 연구에서는 도파민 $D_2$-수용체의 선택적인 효능약으로 알려진 apomorphine이 흰쥐 적출 관류 부신에서 카테콜아민(CA)분비작용에 미치는 영향을 연구코자 시도하여 다음과 같은 연구결과를 얻었다. $10{\um}M\;Apomorphine$의 비교적 낮은 농도를 부신정맥내에 20분간 관류 하였을때 5.32mM ACh, 56mM KCl, $100{\mu}M$ DMPP 및 $100{\mu}M$ McN-A-343 등의 투여에 의한 CA 분비작용이 의의 있게 감소되었다. Apomorphine 농도를 $30{\mu}M$로 증가시켜 관류하였을때 상기약물에 의한 CA 분비작용은 더욱 억제되었으며 또한 Bay-K-8644에 의한 $100{\mu}M$의 고농도로 전처치 하였을때, ACh, excess $K^+$, DMPP 및 McN-A-343에 의한 CA분비작용은 현저히 차단되었다. 도파민 $D_2$-수용체 차단제인 metoclopramide $(30{\mu}M)$으로 20분간 관류 하였을때 ACh, DMPP 및 McN-A-343에 의한 CA 분비작용은 유의하게 억제된 효과를 나타내었으나 $excess\;{K^+}$에 의한 CA분비작용은 별다른 영향을 받지 않았다. 그러나 metoclopramide $(30{\mu}M)$ 존재하에서 $30{\mu}M$ apomorphine으로 20분간 전처치 하였을때 $excess{K^+}$ 뿐만 아니라 DMPP의 CA 분비작용은 별다른 변화를 받지 않았다. 이상과 같은 실험 연구결과를 종합하여 보면, apomorphine은 cholinergic receptor stimulation과 membrane depolarization에 의한 CA 분비작용을 용량의존적으로 억제하여, 이러한 작용은 억제성 도파민 수용체를 활성화 시킴으로써 흰쥐 부신 수질의 chromaffin cell 내로 칼슘의 유입을 억제하여 나타나는 것으로 사료된다.

• 대한약리학회지
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• 제30권3호
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• pp.291-297
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• 1994

이 연구에서는 선조체에서 opioid 신경계와 dopamine 신경계의 상호 관계를 알아보기 위해서 morphine을 5m/kg, 20 mg/kg로 10일간 복강내 투여한 후 chlorpromazine, thioridazine, haloperidol, sulpiride, pimozide를 투여하였다. Opioid ${\mu},\;{\delta},\;{\kappa}$ 수용체의 binding의 변화를 관찰하고자 $[^3H]\;DAGO$, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ binding assay를 하였으며, 그 결과 morphine (20 mg/kg) 장기 투여된 실험군에서 $[^3H]\;DAGO$, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ 결합이 감소되었다. Morphine 20 mg/kg 장기 투여군에 chlorpromazine, thioridazine 주사시에는 morphine 5mg/kg 투여군에 비하여 $[^3H]\;DAGO$ 결합의 감소와, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ 결합의 증가를 나타내었고, haloperidol 주사군은 $[^3H]\;DAGO$, $[^3H]\;DPN$ 결합의 감소, 및 $[^3H]\;DPDPE$ 결합의 증가를 나타내었다. Sulpiride, pimozide 주사군은 morphine 5 m/kg 투여군에 비하여 20m/kg 투여군에서 $[^3H]\;DAGO$, $[^3H]\;DPDPE$, 및 $[^3H]\;DPN$ 결합의 증가를 나타내었다. 이상의 결과로 보아 각 약물간의 opioid 결합에 대한 차이점은 있었으나, morphine 5mg/kg 투여군보다 20m/kg 투여군에서 $[^3H]\;DPDPE$ 및 $[^3H]\;DPN$의 결합이 증가의 경향을 보임으로써, 다량의 morphine을 투여했을 때 ${\mu}\;opioid$ 수용체에 비하여 ${\delta}와 ${\kappa}\;opioid$ 수용체가 더 활성화되는 것을 알 수 있었다.

• Clinical and Experimental Reproductive Medicine
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• 제23권3호
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• pp.269-275
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• 1996

Biosynthesis and secretion of anterior pituitary hormones are under the control of specific hypothalamic stimulatory and inhibitory factors. Among them, Growth Hormone Releasing Hormone (GHRH) is the major stimulator of pituitary somatotrophs activating GH gene expression and secretion. Human GHRH is a polypeptide of 44 amino acids initially isolated from pancreatic tumors, and the gene for the hypothalamic form of GHRH is organized into 5 exons spanning over 10 kilobases (kb) on genomic DNA and encodes a messenger RNA of 700-750 nucleotides. Several neuropeptides classically associated with the hypothalamus have been found in the extrahypothalamic regions, suggesting the existence of novel sources, targets and functions. GHRH-like immunoreactivity has been found in several peripheral sites, including placenta, testis, and ovary, indicating that GHRH may also have regulatory roles in peripheral reproductive organs. Furthermore, higher molecular weight forms of the GHRH transcripts were identified from these organs (1.75 kb in testis; 1.75 and >3 kb in ovary). These tissue-specific expression of GHRH gene suggest the existence of unique regulatory mechanism of GHRH expression and function in these organs. In fact, placenta-specific and testis-specific promoters for GHRH transcripts which are located in about 10 kb upstream region of hypothalamic promoter were reported. The use of unique promoters in extrahypothalamic sites could be refered in a different control of GHRH gene and different functions of the translated products in these tissues. Somatotrophs and lactotrophs have been thought to be derived from a common bipotential progenitor, the somatolactotrophs, which give origins to either phenotypes. Although the precise mechanism responsible for the lactotroph differentiation in the anterior pituitary gland has not been yet clalified, there are several candidators for the generation of lactotrophs. In human, the presence of GHRH peptides with different size from authentic hypothalamic form in the normal anterior pituitary and several types of adenoma were demonstrated. Recently our group found the existence of immunoreactive GHRH and its transcript from the normal rat anterior pituitary (gonadotroph> somatotroph> lactotroph), and the GHRH treatment evoked the increased proliferation rate of anterior pituitary cells in vitro. The transgenic mouse models clearly shown that GHRH or NGF overexpression by anterior pituitary cells induced development of pituitary hyperplasia and adenomas particularly GH-oma and prolactinoma. Taken together, we hypothesize that the pituitary GHRH could serve not only as a modulator of hormone secretion but as a paracrine or autocrine regulator of anterior pituitary cell proliferation and differentiation. Interestingly enough, the expression of Pit-1 homeobox gene (the POU class transcription factor) was confined to somatotrophs, lactotrophs and somatolactotrophs in which GHRH receptors are expressed commonly. Concerning the mechanism of somatolactotroph and lactotroph differentiation in the anterior pituitary, we have focused following two possibilities; (1) changes in the relative levels or interactions of both hypothalamic and intrapituitary factors such as dopamine, VIP, somatostatin, NGF and GHRH; (2) alterations of GHRH-GHRH receptor signaling and Pit-1 activity may be the cause of lactotroph differentiation or pituitary hyperplasia and adenoma formation. Extensive further studies will be necessary to solve these complicated questions.