Involvement of a Novel Organic Cation Transporter in Paeonol Transport Across the Blood-Brain Barrier

Paeonol has neuroprotective function, which could be useful for improving central nervous system disorder. The purpose of this study was to characterize the functional mechanism involved in brain transport of paeonol through blood-brain barrier (BBB). Brain transport of paeonol was characterized by internal carotid artery perfusion (ICAP), carotid artery single injection technique (brain uptake index, BUI) and intravenous (IV) injection technique in vivo. The transport mechanism of paeonol was examined using conditionally immortalized rat brain capillary endothelial cell line (TR-BBB) as an in vitro model of BBB. Brain volume of distribution (V(D)) of [³H]paeonol in rat brain was about 6-fold higher than that of [¹⁴C]sucrose, the vascular space marker of BBB. The uptake of [³H]paeonol was concentration-dependent. Brain volume of distribution of paeonol and BUI as in vivo and inhibition of analog as in vitro studies presented significant reduction effect in the presence of unlabeled lipophilic compounds such as paeonol, imperatorin, diphenhydramine, pyrilamine, tramadol and ALC during the uptake of [³H]paeonol. In addition, the uptake significantly decreased and increased at the acidic and alkaline pH in both extracellular and intracellular study, respectively. In the presence of metabolic inhibitor, the uptake reduced significantly but not affected by sodium free or membrane potential disruption. Similarly, paeonol uptake was not affected on OCTN2 or rPMAT siRNA transfection BBB cells. Interestingly. Paeonol is actively transported from the blood to brain across the BBB by a carrier mediated transporter system.

Mechanisms of histamine ameliorating memory impairment induced by pentylenetetrazole-kindling epilepsy in rats / 浙江大学学报·医学版

To investigate the effects of neuronal histamine on spatial memory acquisition impairment in rats with pentylenetetrazole-kindling epilepsy, and to explore its mechanisms.A subconvulsive dose of pentylenetetrazole (35 mg/kg) was intraperitoneally injected in rats every 48 h to induce chemical kindling until fully kindled. Morris water maze was used to measure the spatial memory acquisition of the rats one week after fully pentylenetetrazole-kindled, and the histamine contents in different brain areas were measured spectrofluorometrically. Different dosages of hitidine (the precursor of histamine), pyrilamine (H1 receptor antagonist), and zolantidine (H2 receptor antagonist) were intraperitoneally injected, and their effects on spatial memory acquisition of the rats were observed.Compared with control group, escape latencies were significantly prolonged on Morris water maze training day 2 and day 3 in pentylenetetrazole-kindling epilepsy rats (all<0.05); and the histamine contents in hippocampus, thalamus and hypothalamus were decreased significantly (all<0.05). Escape latencies were markedly shortened on day 3 by intraperitoneally injected with histidine 500 mg/kg, and on day 2 and day 3 by intraperitoneally injected with histidine 1000 mg/kg in pentylenetetrazole-kindling epilepsy rats (all<0.05). The protection of histidine was reversed by zolantidine (10 and 20 mg/kg), but not by pyrilamine.Neuronal histamine can improve the spatial memory acquisition impairment in rats with pentylenetetrazole-kindling epilepsy, and the activation of H2 receptors is possibly involved in the protective effects of histamine.

Imperatorin is Transported through Blood-Brain Barrier by Carrier-Mediated Transporters

Imperatorin, a major bioactive furanocoumarin with multifunctions, can be used for treating neurodegenerative diseases. In this study, we investigated the characteristics of imperatorin transport in the brain. Experiments of the present study were designed to study imperatorin transport across the blood-brain barrier both in vivo and in vitro. In vivo study was performed in rats using single intravenous injection and in situ carotid artery perfusion technique. Conditionally immortalized rat brain capillary endothelial cells were as an in vitro model of blood-brain barrier to examine the transport mechanism of imperatorin. Brain distribution volume of imperatorin was about 6 fold greater than that of sucrose, suggesting that the transport of imperatorin was through the blood-brain barrier in physiological state. Both in vivo and in vitro imperatorin transport studies demonstrated that imperatorin could be transported in a concentration-dependent manner with high affinity. Imperatorin uptake was dependent on proton gradient in an opposite direction. It was significantly reduced by pretreatment with sodium azide. However, its uptake was not inhibited by replacing extracellular sodium with potassium or N-methylglucamine. The uptake of imperatorin was inhibited by various cationic compounds, but not inhibited by TEA, choline and organic anion substances. Transfection of plasma membrane monoamine transporter, organic cation transporter 2 and organic cation/carnitine transporter 2/1 siRNA failed to alter imperatorin transport in brain capillary endothelial cells. Especially, tramadol, clonidine and pyrilamine inhibited the uptake of [3H]imperatorin competitively. Therefore, imperatorin is actively transported from blood to brain across the blood-brain barrier by passive and carrier-mediated transporter.

Role of histamine H(1) and H(2) receptors in the modulation of respiratory rhythmical discharge in medulla oblongata slice preparation of neonatal rats / 生理学报

The present study was carried out to determine the role of histamine H(1) and H(2) receptors in the generation of basic respiratory rhythm. Neonatal (aged 0-3 d) Sprague-Dawley rats of either sex were used. The medulla oblongata slice containing the medial region of the nucleus retrofacialis (mNRF) and the hypoglossal nerve rootlets was prepared and the surgical procedure was performed in the modified Kreb's solution (MKS) with continuous carbogen (95% O(2) and 5% CO(2)), and ended in 3 min. Respiratory rhythmical discharge activity (RRDA) of the rootlets of hypoglossal nerve was recorded by suction electrode. Thirty medulla oblongata slice preparations were divided into 5 groups. In groups I, II and III, histamine (5 μmol/L), H(1) receptor specific antagonist pyrilamine (10 μmol/L) and H(2) receptor specific antagonist cimetidine (5 μmol/L) was added into the perfusion solution for 15 min separately. In group IV, after application of histamine for 15 min, additional pyrilamine was added into the perfusion for another 15 min. In group V, after application of histamine for 15 min, additional cimetidine was added into the perfusion for another 15 min. The discharges of the roots of hypoglossal nerve were recorded. Signals were amplified and band-pass filtered (100-3.3 kHz). Data were sampled (1-10 kHz) and stored in the computer via BL-420 biological signal processing system. Our results showed that histamine significantly decreased the respiratory cycle (RC) and expiratory time (TE), but changes of integral amplitude (IA) and inspiratory time (TI) were not statistically significant. Pyrilamine induced significant increases in RC and TE, but changes of TI and IA were not statistically significant. Cimetidine had no effects on RC, TE, TI and IA of RRDA. The effect of histamine on the respiratory rhythm was reversed by additional application of pyrilamine but not cimetidine. Taken together, with the results mentioned above, histamine H(1) receptors but not H(2) receptors may play an important role in the modulation of RRDA in the medulla oblongata slice preparation of neonatal rats.

Estudo do envolvimento das vias histaminérgicas no controle da ingestão de água e sal em ratos / Study the involvement of the tracks histaminérgicas in controlling the intake of water and salt in rats

Os diferentes mecanismos cerebrais de controle do comportamneto de ingestão hídrica desencadeado pela sede, bem como o apetite específico por sódio têm sido objetos de investigação de diversos grupos de pesquisas. A participação das vias histaminérgicas centrais e de seus receptores no controle do equilíbrio hidrossalino do organismo ainda não está completamente esclarecida. Dados da literatura mostram que as vias histaminérgicas centrais através dos seus receptores dos tipos HI e H2 participam dos mecanismos de controle da ingestão hídrica em animais normhidratados e da ingestão de água pós-prandial. Decidiu-se então investigar o papel dos receptores histaminérgicos centrais dos tipos HI e H2 no controle da ingestão hídrica em diferentes situações de desafio homeostático - hiperosmolaridade e hipovolemia, além da verificação da possível interação entre as vias histaminérgicas e colinérgicas centrais no controle da ingestão hídrica. Investigou-se também a participação desses receptores histaminérgicos nos mecanismos de controle do apetite específico por sódio desencadeado em situações de depleção deste íon, privação de líquidos e estimulação angiotensinérgica central. Os resultados obtidos neste estudo mostram uma maior funcionalidade dos receptores histaminérgicos do tipo HI em situações fisiológicas que provocam modificações nas condições osmóticas dos compartimentos de líquidos corporais, além da existência de uma inter-relação das vias histaminérgicas através dos receptores do tipo HI e as vias colinérgicas centrais sobre o controle da ingestão hídrica. A participação dos receptores do tipo H2 está relacionada a alterações do volume dos líquidos corporais, bem como à resposta dipsogênica desencadeada pela angiotensina 11. Os resultados obtidos neste trabalho trazem importantes informações que contribuem para o entendimento da participação das vias histaminérgicas no controle do equilíbrio hidrossalin, evidenciando as interações destas vias com outras VIas neurotransmissoras centrais no controle da homeostasia hidrossalina do organismo.

Avaliação clínica da eficácia e segurança da associação hidróxido de alumínio, ácido acetilsalicílico, maleato de mepiramina e cafeína* no tratamento sintomático de cefaléia, náuseas e fadiga/mialgia após o uso de bebidas alcoólicas / The efficacy and safety of the association of aluminium hydroxide, acetylsalicylic acid, mepyramine maleate and caffeine in the treatment of headache nausea and fatigue/myalgia after alcohol ingestion

A associação hidróxido de alumínio, ácido acetilsalicílico, maleato de mepiramina e cafeína (ENGOV) foi avaliada quanto a eficácia e segurança no tratamento sintomático de cefaléia, náuseas e fadiga/mialgia após o uso de bebidas alcoólicas, sintomas denominado "ressaca". Foram avaliados 99 pacientes divididos em quatro grupos com idade entre 18 e 40 anos, de acordo com a posologia indicada: Grupo A: pacientes que utilizaram um comprimido no episódio de "ressaca" e depois de 60 minutos da ingestão, não tomaram mais comprimidos; Grupo Aa: pacientes que tomaram um comprimido no episódio de "ressaca" e 60 minutos depois, permanecendo os sintomas, tomaram mais um comprimido do medicamento; Grupo Ab: pacientes que tomaram um comprimido no episódio desses mesmos sintomas e 60 minutos depois, permanecendo os sintomas, tomaram mais dois comprimidos do medicamento; Grupo Ac: pacientes que tomaram um comprimido no episódio e 60 minutos depois, permanecendo os sintomas, tomaram mais três comprimidos do medicamento. Os resultados obtidos relacionados à segurança do uso da medicação demonstraram excelente tolerabilidade para todos os casos em todos os grupos de posologia. Não foram relatadas reações adversas. Diante do conjunto de informações obtidas neste estudo, ficou demonstrada a excelente eficácia e tolerabilidade da associação hidróxido de alumínio, ácido acetilsalicílico, maleato de mepiramina e cafeína no tratamento sintomático de cefaléia, náuseas e fadiga/mialgia após o uso de bebidas alcoólicas.

Investigation of comparative pharmacological responsiveness of rat subcutaneous fascia and excisional wound granulation tissues

In the present in vitro study, using superfusion technique, the pharmacological responsiveness of the excisional wound granulation tissue myofibroblasts to a variety of agents were compared with those of normal connective tissue taken from the superficial fascia. Bolus doses of angiotensin II [0.1 to 1000nM], mepyramine [1 to 128 micro M], calcium chloride [75 to 300 micro M] and potassium chloride [100 to 400 micro M] were added to the superfusate solution and the responses were recorded on Narco chart recorder. The results showed that both types of tissues have qualitatively similar characteristic responsiveness to potassium and calcium ions, mepyramine and angiotensin II. However, quantitatively, they were distinctly different, the myofibroblasts from granulation tissues produced greater contractile responses to mepyramine and angiotensin II, whilst they lost most of their responsiveness to potassium and calcium ions. The present study demonstrated that these tissues respond to pharmacological manipulation, but the responses they produce are distinct from smooth muscle cells and need to be considered further in experiments involving wound healing

Hippocampal histamine receptors and conflictive exploration in the rat: studies using the elevated asymmetric plus-maze

The possible role of histamine receptors in the hippocampal formation on the exploratory motivation and emotionality of the rat was studied. An elevated asymmetric plus-maze composed of 4 different arms (no walls, single high wall, high and low walls and two high walls) arranged at 90 degrees angles was used. The exploration score, considered to be an index of exploratory motivation, and the permanency score, considered to be an index of emotionality (anxiety), were determined. Histamine was administered locally into the ventral hippocampus at three different doses (9,45 and 90 nmol). Another group of rats was also microinjected with 45 nmol of pyrilamine (a histamine H1 receptor antagonist) or ranitidine (a histamine H2 receptor antagonist) in addition to 9 nmol of histamine in order to identify the possible type of histamine receptor involved. Histamine administration significantly inhibited the exploration score and increased the permanency score at the doses of 9 and 45 nmol in two of four arms. These effects were completely blocked by the administration of eitheer histamine receptor antagonist. The present results suggest that in the hippocampal formation histamine inhibits exploratory motivation and decreases emotionality by activating both types of histamine receptors. Also, the elvated asymmetric plus-maze appears to be a suitable technique to quantify exploration and possibly "anxiety".

Effect of histaminergic drugs on integumental melanophores of adult Bufo melanostictus.

Histamine and 2-methyl histamine caused dose-dependent aggregation of melanophores in toad B. melanostictus. The effects were effectively antagonised by mepyramine, a specific H1 histamine receptor antagonist, and metiamide a specific H2 receptor antagonist. On the other, hand 4-methyl histamine, a specific H2 receptor agonist dispersed the melanophores. The results suggest that adult Bufo melanophores have H1 histamine receptors which mediate melanophore aggregation, however, dispersion of melanophores may be controlled by undifferentiated histamine receptors of H2 type.

"In vivo" and "in vitro" antitumoral action of Larrea divaricata cav

We previously reported that aqueous extract of Larrea divaricata Cav had an antiproliferative activity upon tumoral lymphoid cells (BW 5147), without affecting normal immunity. To determine the probable mechanism of the inhibitory action of the extract upon cell growth, the participation of intracellular signals involved in the inhibition of cell proliferation, namely the activation of adenylate cyclase system was studied. The production of cyclic 3', 5 adenosine monophosphate (cAMP) in presence and absence of extract was analized. The extract increased the cAMP levels, but neither the cAMP production nor the inhibitory effect of the extract on proliferation were blocked by a beta adrenergic receptor antagonist (propranolol) or by histaminergic receptor antagonistis (cimetidine and mepyramine). So, we concluted that the antiproliferative activity of the extract of BW 5147 cells would be mediated by an increase in cAMP intracellular levels no related to the activation of the membrane receptors here studied. In parallel, the extract was administered to a pregnant rat with a spontaneous mammarian carcinoma and "in vivo"antitumoral activity was found.

Hippocampus and learning. Possible role of histamine receptors

The effect of local adminstration of histamine and its receptor antagonists into the hippocampus on the learning process of an active avoidance response was studied. The task that the animals had to learn consisted in avoiding an electric shock on their feet after a conditioning ultrasonic 40 kHz tone was on. Latency time was defined as the time in serc rats took to avoid or escape the eletric shock: per cent CAR was defined as the cummulative positive responses during learning session. All rats were implanted into the ventral hippocampus with guide cannulae. On the day of the experiment, rats were microinjected through the guide cannulae with 1 mug of saline solution containing 67.5 nmol of ranitidine or pyrilamine alone or in combination with 45 nmol histamine. All groups were subjected to two sessions of learning. Results show that treatment with histamine was effective to block the adquisition of the response, since animals showed a learning curve significantly inferior to that of the controls. Ranitidine treatment was not able to block the histamine effect. Pyrilamine treatment, instead, was effective to block the inhibitory action of histamine on learning. Results suggest that histamine in hippocampus may be exerting a modulatory control on retrieval processes of memory.

The study for the roles of intratracheally administered histamine in the neutrophil-mediated acute lung injury in rats: / 결핵

BACKGROUND: Neutrophils are considered to play critical roles in the development of acute respiratory distress syndrome. Histamine, which is distributed abundantly in lung tissue, increases the rolling of neutrophills via increase of P-selectin expression on the surface of endothelial cells and is known to have some interrelationships with IL-1, IL-8 and TNF-alpha. We studied to investigate the effect of the histamine on the acute lung injury of the rats induced by intratracheal insufflation of TNF-alpha which has less potency to cause lung injury compared to IL-1 in rats. METHODS: We intratracheally instilled saline or TNF(R&D, 500ng), IL-1(R&D, 50ng)or histamine of varius dose(1.1, 11 and 55 microg/kg) with and without TNF separately in Sprague-Dawley rats weighing 270-370 grams. We also intratracheally treated IL-l(50ng) along with histamine(55 microg/kg). In cases, there were synergistic effects induced by histamine on the parameters of TNF-induced acute lung injury, antihistainmes(Sigma, mepyramine as a H1 receptor blockade and ranitidine as a H2 receptor blockade, 10 mg/kg in each)were co-administered intravenously to the rats treated TNF along with histamine(1.1 microg/kg) intratracheally. Then after 5 h we measured lung lavage neutrophil numbers, lavage cytokine-induced neutrophil chemoatt- ractants(CINC), lung myeloperoxidase activity(MPO) and lung leak. We also intratracheally insufflated TNF with/without histamine(11 microg/kg), then after 24 h measured lung leak in rats. Statistical analyses were done by Kruskal-Wallis nonparametric ANOVA test with Dunn's multiple comparison test or by Mann-Whitney U test. RESULTS: We found that rats given TNF, histamine alone(11 and 55 microg/kg), and TNF with histamine(1.1, 11, and 55 microg/kg) intratracheally had increased (P<0.05) lung MPO activity compared with saline-treated control rats. TNF with histamine 11 microg/kg had increased MPO activity (P=0.0251) compared with TNF-treated rats. TNF and TNF with histamine(l.l, 11,, and 55 microg/kg) intratracheally had all increased (P<0.05) lung leak, lavage neutophil numbers and lavage CINC activities compared with saline. TNF with histamine 1.1 microg/kg had increased (P=0.0367) lavage neutrophil numbers compared with TNF treated rats. But there were no additive effect of histamine with TNF compared with TNF alone in acute lung leak on 5 h and 24 h in rats. Treatment of rats with the H1 and H2 antagonists resulted in inhibitions of lavage neutrophil accumulations and lavage CINC activity elevations elicited by co-treated histamine in TNF-induced acute lung injury intratracheally in rats. We also found that rats given IL-1 along with histamine intratracheally did not have increase in lung leak compared with IL-1 treated rats. CONCLUSION: Histamine administered intratracheally did not have synergistic effects on TNF-induced acute lung leak inspite of additive effects on increase in MPO activity and lavage neutrophil numbers in rats. These observations suggest that instilling histamine intratracheally would not play synergistic roles in neutrophil-mediated acute lung injury in rats.

Antihistaminic activity of quinethindole: a 2-substituted pyrazinopyridoindole derivative.

Quinethindole, a 2-substituted pyrazinopyridoindole, showed specific antihistaminic (H1) activity in various in vivo and in vitro test models. It also inhibited antigen-induced contraction of ileum of sensitized guinea pig. The antihistaminic activity was of competitive nature.

Effects of antihistamines on wound healing.

Role of antihistamines (H1 and H2 blockers) in wound healing by utilizing incision and dead space wound models in albino rats was investigated. H1 blockers (mepyramine and promethazine) were found to decrease breaking strength of 10 day old dermal incision wounds and collagen content (as hydroxyproline) and breaking strength of granulation tissue harvested over tubular implant. On the other hand H2 blockers (Cimetidine and ranitidine) did not alter the above parameters. The findings that H1 blockers suppress healing implicate H1 receptors in alleged prohealing effect of histamine, and suggest clinical evaluation of these agents for suppression of overhealing states like keloid, adhesions and strictures.

Role of endogenous opioids and histamine in morphine induced emesis.

The role of opioid and histaminergic system in morphine induced emesis was investigated in dogs. Morphine (25 micrograms, icv) consistently evoked emesis with an average latency of 195 +/- 29 sec which was fully accounted for by an action on the chemoreceptor trigger zone (CTZ) as its ablation rendered animals refractory to vomiting. Intraventricular pretreatment with opioid antagonist naloxone, histamine H1 antagonist mepyramine and H2 antagonists metiamide and cimetidine afforded protection to icv morphine emesis. The CSF histamine concentration was significantly raised 5 min after icv morphine administration. The results suggest that both endogenous opioid and histamine are involved in morphine emesis. Naloxone in high doses (1600 micrograms, icv) elicited emesis which was not blocked by CTZ ablation confirming our earlier report.

Demonstration of histamine receptors on the surface of Entamoeba histolytica.

Histamine receptors on the surface of E. histolytica could be demonstrated by histochemical method using three isolates of the protozoa grown and maintained in modified Boeck and Drbohlav's medium. Prior treatment of E. histolytica with cimetidine a H2 blocker, blocked the histamine uptake. Similar treatment with mepyramine maleate, a H1 blocker, did not prevent histamine uptake by the protozoa. It is postulated that E. histolytica has H2 receptors on its surface.

Involvement of histamine receptors in mediation of histamine induced thermoregulatory response in rats.

At there ambient air temperature range, the rectal temperature changes following infusion of histamine either into lateral ventricle (L.V.) or IVth ventricle (IVth V) were studied. At an ambient temperature range of 19-22 degrees C, hypothermia occurred following histamine infusion either into L.V. or IVth V. Hypothermia elicited from infusion of histamine into L.V. was prevented with pretreatment of H1-receptor blocker (mepyramine), but in case of IVth V, it was prevented with H2-receptor blocker(cimetidine). These H1 and H2-receptor antagonists were ineffective in preventing hypothermia following histamine infusion into either L.V. or IVth V, when the ambient air temperature was maintained low (11-13 degrees C).