Striatal topography of D-2 receptors correlates with indexes of cholinergic neuron localization

The topography of dopamine D-2 receptor sites determined from autoradiographs of the rat striatum was compared with previously published values for choline acetyltransferase activity and high-affinity choline uptake within subregions of the striatum. The density of D-2 sites in the caudate-putamen correlates strikingly with these indexes of cholinergic neuron distribution.     

Water and salt consumption and suppression of angiotensin-induced thirst in rats after carotid glomectomy

Carotid glomectomy in rats reduced daily water consumption and increased daily consumption of NaCl solution. Sham operation did not modify water and salt consumption. Intraperitoneal injection of angiotensin-II did not stimulate drinking motivation in the majority of rats subjected to carotid glomectomy. Injection of angiotensin-II to sham-operated and intact animals induced active consumption of both fluids during one hour. These results attest to the involvement of the carotid body in the regulation of consumption of water and sodium ions (the main elements of osmotic blood pressure) and the involvement of angiotensin-sensitive receptors of carotid body cells in the formation of thirst and salt appetite motivation, regulated by the renin-angiotensin system.Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 138, No. 11, pp. 493–495, November, 2004     

Immunohistochemical localization of angiotensin AT1 receptors in the rat carotid body

The carotid body (CB) is a major peripheral arterial chemoreceptor that initiates respiratory and cardiovascular adjustments to maintain homeostasis. Recent evidence suggests that circulating or locally produced hormones like angiotensin II acting via AT₁ receptors modulate its activity in a paracrine-autocrine manner. The aim of this study was to examine the immunohistochemical localization of AT₁ receptor in the CB of adult rats and to compare its expression in vehicle-treated animals, and after the long-term application of its selective blocker losartan. Immunohistochemistry revealed that a subset of CB glomeruli and the vast majority of neurons in the adjacent superior cervical ganglion (SCG) were strongly AT₁ receptor-immunoreactive. In the CB immunostaining was observed in the chemosensory glomus cells typically aggregated in cell clusters while the nerve fibers in-between and large capillaries around them were immunonegative. Exogenous administration of losartan for a prolonged time significantly reduces the intensity of AT₁ receptor immunostaining in the CB glomus cells and SCG neurons. Our results show that AT₁ receptors are largely expressed in the rat CB under physiological conditions, and their expression is down-regulated by losartan treatment.     

Bilateral carotid body tumor: the role of fine-needle aspiration biopsy in the preoperative diagnosis

Carotid body (CB) is a round to ovoid or flattened structure situated within the adventitia of the common carotid artery bifurcation on both sides of the neck. CB contains two basic types of cells: chief cells (or glomus type 1) and sustentacular cells (glomus type 2). Carotid body tumor (CBT) or paraganglioma arises from the chief cells of the carotid body. The diagnosis of CBT is typically made with radiological studies. Fine needle aspiration biopsy (FNAB) is seldom requested for this purpose due to rare but dreadful reported complications such as hemorrhage and damage to the carotid artery. In this report we discuss the cytological findings of a malignant CBT diagnosed by FNAB in a 22 year-old female.     

Immunohistochemical localization of carbonic anhydrase isozymes in the rat carotid body

The rat carotid body was immunohistochemically stained for carbonic anhydrase I, II and III (CA-I, CA-II and CA-III). Immunoreactivity for CA-I was distributed in type I cells, type II cells and nerve bundles. Smooth muscle cells and endothelial cells of blood vessels were also strongly stained for CA-I. CA-II immunoreactivity was distinctly positive in type I cells and nerve bundles. Vascular smooth muscle cells were weakly positive, and type II cells were negative for CA-II. CA-III immunoreactivity was identified in type I cells and vascular smooth muscle cells. Our results suggest that carbonic anhydrase isozymes in type I cells play an important role in chemoreception for hypercapnia. Immunoreactivities for CA-I and CA-II in the nerve fibres may participate in the synergic action of carotid sinus nerve between hypoxic and hypercapnic stimuli.     

D-2-hydroxyglutarate produced by mutant IDH2 causes cardiomyopathy and neurodegeneration in mice

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) have been discovered in several cancer types and cause the neurometabolic syndrome D2-hydroxyglutaric aciduria (D2HGA). The mutant enzymes exhibit neomorphic activity resulting in production of D2-hydroxyglutaric acid (D-2HG). To study the pathophysiological consequences of the accumulation of D-2HG, we generated transgenic mice with conditionally activated IDH2^R140Q and IDH2^R172K alleles. Global induction of mutant IDH2 expression in adults resulted in dilated cardiomyopathy, white matter abnormalities throughout the central nervous system (CNS), and muscular dystrophy. Embryonic activation of mutant IDH2 resulted in more pronounced phenotypes, including runting, hydrocephalus, and shortened life span, recapitulating the abnormalities observed in D2HGA patients. The diseased hearts exhibited mitochondrial damage and glycogen accumulation with a concordant up-regulation of genes involved in glycogen biosynthesis. Notably, mild cardiac hypertrophy was also observed in nude mice implanted with IDH2^R140Q-expressing xenografts, suggesting that 2HG may potentially act in a paracrine fashion. Finally, we show that silencing of IDH2^R140Q in mice with an inducible transgene restores heart function by lowering 2HG levels. Together, these findings indicate that inhibitors of mutant IDH2 may be beneficial in the treatment of D2HGA and suggest that 2HG produced by IDH mutant tumors has the potential to provoke a paraneoplastic condition.     

Adenosine triphosphate content in the cat carotid body under different arterial O2 and CO2 conditions

The adenosine triphosphate (ATP) level in the carotid body has often been discussed as the crucial step in the chemoreceptive process. Therefore, the ATP level of the cat carotid body was investigated with the aid of the bioluminescence method under different stimulation conditions. Under normoxic conditions an ATP level of about 0.087 nmol/glomus was measured, which is very low in comparison to other organs. The level did not change significantly, neither under hypoxic nor hypercapnic conditions. From these results we conclude that the primary effect of the chemoreceptive process in the carotid body cannot be explained by changes of the ATP level under different stimulation conditions.     

Fine-needle aspiration diagnosis of carotid body tumor: Report of a case and review of experience with cytologic features in four cases

A 45-yr-old female presented with a left upper cervical swelling of 4 yr duration. The clinical suspicion of carotid body tumor (CBT) was confirmed by imaging findings, fine-needle aspiration (FNA) cytology, and histology of the resected tumor. Review of our experience with four cases including the present one during 10 yr (1984–1994) showed that the age of the patients ranged from 35 to 45 yr with a mean of 40.8 yr. All four cases were females and had left-sided upper cervical swelling. Clinically one case was diagnosed as cervical lymphadenopathy and there was clinical suspicion of CBT in two cases. Findings of digital subtraction angiogram in four cases and ultrasonography including Doppler ultrasound vascular imaging in three cases were consistent with CBT. The cytodiagnosis was CBT in three cases and inadequate (blood only) in one case. The analysis of detailed cytologic features in three cases revealed blood-rich aspirate with poor to moderate cellularity, indistinct cell outline, and acinar formation. Giant bare nuclei, spindle-shaped tumor cells, and cytoplasmic granulations were observed in two cases each. Histopathology of the resected tumors in two cases confirmed the cytodiagnosis of CBT. FNA cytology played a useful role in arriving at a tissue diagnosis of this rare neoplasm. Diagn. Cytopathol. 17:143–147, 1997. © 1997 Wiley-Liss, Inc.     

Inhibition of the in vitro growth of Plasmodium falciparum by D vitamins and vitamin D-3 derivatives

D vitamins are effective inhibitors of the in vitro intraerythrocytic growth of Plasmodium falciparum. Disappearance of the parasitemia was observed after 48 h contact between infected cells and 5 x 10(-6) M 1 alpha-hydroxycholecalciferol, 5 x 10(-5) M 25-hydroxycholecalciferol (25-OH-D-3), 1 alpha, 25-dihydroxycholecalciferol or 2.5 x 10(-4) vitamin D-2 and D-3. A 48 h pretreatment of healthy erythrocytes with 5 x 10(-5) M 25-OH-D-3 did not change their susceptibility to invasion by the parasite and their ability to support the growth of P. falciparum. Ionomycin, a calcium ionophore, and EGTA prevented parasite development at concentrations greater than 2 x 10(-7) M and 4 x 10(-4) M, respectively, but did not antagonize the inhibitory activity of 25-OH-D-3. Addition of 25-OH-D-3 for 12 or 24 h duration to synchronized cultures, showed that the drug had a schizonticidal action, but was without effect when parasites were in the ring form.     

Effects on the rabbit carotid body of stimulation by almitrine, natural high altitude, and experimental normobaric hypoxia

Rabbits were given intraperitoneal injections of almitrine in ascending doses for 5 weeks. They were compared with a control group and with a group of rabbits which had been exposed from birth to the natural hypobaric hypoxia found at Cerro de Pasco (433 m) in the Peruvian Andes. A further group of animals was placed in an experimental normobaric chamber for either 3 or 6 months to subject them to the same degree of hypoxia as that occurring in Cerro. The carotid bodies of the rabbits in all these groups were processed for light and electron microscopy, and examined both qualitatively and quantitatively. The carotid bodies in the group given almitrine showed no changes in their size or in the population of their glomic cells when compared with controls. In contrast, the carotid bodies of Peruvian rabbits were greatly enlarged with a disproportionate increase in the population of the light variant of chief cell. Rabbits from the hypoxic chamber also had enlarged carotid bodies but those killed after 3 months showed an increase in the dark variant of chief cell, whereas after 6 months this cell was reduced in number. There was also intense cytoplasmic vacuolation. Election microscopy confirmed these changes and revealed that dark cells had larger, more pleomorphic granules than the light variant. Vacuolation of the granules in light cells was most pronounced in Peruvian rabbits, but was uncommon in animals exposed to hypoxia for 3 months. We suggest that the dark cell responds to the early stages of hypoxia but later matures into the light variant of chief cell.     

Expression of HIF-1alpha, VEGF and VEGF receptors in the carotid body of chronically hypoxic rat

We examined the protein expression and localization of HIF-1alpha, VEGF, VEGF receptors in the carotid body (CB) of rats breathing 10% inspired oxygen for up to 4 weeks. The immunoreactivity (IR) of HIF-1alpha was distributed numerously in the nuclei of glomus (type-I) and other cells since hypoxia for 1 day, but was faint and scattered in the normoxic CBs. Cytoplasmic staining of the VEGF was intense in glomus cells of the hypoxic but not the normoxic group. The IR levels of HIF-1alpha and VEGF reached plateau at 4 weeks, and the IRs of VEGFR-1 and VEGFR-2 were strongly positive in the hypoxic group. Yet, the expression of VEGFR-1-IR was mild, whereas the VEGFR-2-IR was intense in normoxic CBs, suggesting an upregulation of VEGFR-1 but not VEGFR-2 in hypoxia. Hence, HIF-1 may activate the expression of VEGF and VEGFR-1 in the CB and the expression of VEGF in the chemoreceptors may play a paracrine role in the vascular remodeling during chronic hypoxia.     

Inhibition of adenylate cyclase attenuates muscarinic Ca signaling by a PKA-independent mechanism in rat carotid body Type I cells

Carotid body (CB) Type I cells respond to hypoxia by releasing excitatory and inhibitory neurotransmitters. This mechanism leads to increased firing of the carotid sinus nerve (CSN) which alters breathing to maintain blood gases within the physiological range. Acetylcholine targets both muscarinic and nicotinic receptors in the rat CB, acting postsynaptically on CSN and presynaptically on Type I cells. Muscarinic Ca²⁺ signaling is inhibited by the activation of G_i-coupled receptors including histamine H3 receptors. Here inhibition of adenylate cyclase with SQ22536 mimicked H3 receptor activation. Using Ca²⁺ imaging techniques it was observed that inhibition of muscarinic Ca²⁺ signaling was independent of protein kinase A (PKA) as PKA inhibitors H89 and KT5720 were without effect on the muscarinic Ca²⁺ response. By contrast the Epac (exchange protein activated by cAMP) inhibitor brefeldin A inhibited muscarinic Ca²⁺ signaling whereas the Epac activator 8-pCPT-2′-O-Me-cAMP-AM potentiated Ca²⁺ signaling.     

Inhibition of inositol phospholipid breakdown by D2 dopamine receptors in dissociated bovine anterior pituitary cells

Inositol phospholipids have been labelled with [³H]inositol in a lactotroph-enriched preparation of dissociated bovine anterior pituitary cells. Stimulation of cells with thyrotropin-releasing hormone receptor agonists leads to accumulation of [³H]inositol phosphates, and this effect may be inhibited by dopamine (DA) agonists. The DA agonist effect may be prevented by D₂ DA receptor selective antagonists. Thus the D₂ receptors on these cells are linked to inhibition of inositol phospholipid metabolism, and this provides a functional assay for the receptor.     

Inhibition of lipid peroxidation by antioxidants in the vitreous body during hemorrhage

Research Institute of Ophthalmology, Ministry of Health of the Azerbaidzhan SSR. A. I. Karaev Institute of Physiology, Academy of Sciences of the Azerbaidzhan SSR, Baku. (Presented by Academician of the Academy of Medical Sciences of the USSR G. N. Kryzhanovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 106, No. 9, pp. 291–292, September, 1988.     

Ejaculation induced by i.c.v. injection of the preferential dopamine D(3) receptor agonist 7-hydroxy-2-(di-N-propylamino)tetralin in anesthetized rats

In addition to serotonin, dopamine within the CNS is known to play a primary role in the control of ejaculation. However, whether D(2) and/or D(3) dopamine receptor subtypes mediate this effect is still unclear. In order to clarify this issue, a pharmacological competitive study using the preferential D(3) agonist 7-hydroxy-2-(di-N-propylamino)tetralin (7-OH-DPAT) alone or in combination with competitive nonpreferential or preferential D(2) and D(3) antagonists delivered intracerebroventricularly (i.c.v.) was undertaken in anesthetized rats. Urethane-anesthetized male rats were implanted into the cerebral ventricle with a cannula for i.c.v. injections, and recording electrodes were placed within the bulbospongiosus (BS) muscle to monitor BS muscle contractions, which were used as a marker for the expulsion phase of ejaculation. Following i.c.v. injection, 7-OH-DPAT induced ejaculation and rhythmic BS muscle contractions. Co-injected i.c.v. with 7-OH-DPAT, the nonselective D(2)/D(3) antagonist (raclopride), and the preferential D(3) antagonist (S(-)-N[n-butyl-2-pyrrolidinyl)methyl]-1-methoxy-4-cyanonaphtalene-2-carboxamide; nafadotride) but not the preferential D(2) antagonist ((+/-)-3-[4-(4-chlorophenyl)-4-hydroxypiperidinyl]methylindole; L 741,626) inhibited the occurrence of ejaculation and BS muscle contractions. These results suggest that i.c.v. delivery of 7-OH-DPAT does represent a pertinent model to investigate the physio-pharmacology of ejaculation. It is inferred that targeting brain D(3) receptors may provide a therapeutic approach for treating ejaculatory disorders in humans.     

Differential Ca2+ binding properties in the human cerebellar cortex: distribution of parvalbumin and calbindin D-28k immunoreactivity

Summary The distribution of the Ca²⁺-binding proteins parvalbumin (PV) and calbindin D-28k (CaBP) was investigated in the human cerebellar cortex. Purkinje cells contain both PV and CaBP. PV but not CaBP stains stellate and basket cells in the molecular layer. In the granular layer Golgi neurons can be subdivided into a majority, devoid of both Ca²⁺-binding proteins, and a scanty population which appears to be PV- and CaBP-immunoreactive. Thus GABAergic neurons in the human cerebellar cortex show selective differences in their Ca²⁺-binding properties, and these differences might reflect a heterogeneity in the processing of Ca²-mediated events.Abbreviations CaBP calbindin D-28k - CNS central nervous system - GABA -aminobutyric acid - -IR immunoreactivity - LTD long-term depression - PV parvalbumin     

大麻素CB_1受体活化对神经病理性疼痛大鼠脊髓背角嘌呤能P2X_2受体表达的抑制作用

目的:观察脊髓背角大麻素CB_1受体(CB_1R)在坐骨神经缩窄性损伤(CCI)所致的神经病理性疼痛中的作用及其对嘌呤能P2X_2受体表达的调节。方法:7~8周龄SD大鼠分为4组:(1)sham组;(2)CCI组;(3)CP55940+CCI组;(4)AM251+CP55940+CCI组。分别于CCI术前1 d,术后1、3、5、7、10、14 d测定热缩足反射潜伏期(TWL);免疫印迹技术检测各组大鼠损伤侧L_4~L_6段脊髓背角P2X_2受体表达。结果:CCI术后大鼠出现热痛敏,TWL明显缩短;鞘内给予非选择性大麻素受体激动剂CP55940可明显延长CCI大鼠TWL(P0.05);预先鞘内注射CB_1R拮抗剂AM251(0.05 mg/kg)可显著降低CP55940的镇痛效果(P0.05)。免疫印迹实验结果显示:CCI大鼠脊髓背角P2X_2受体在术后7、14 d表达明显增加(P0.05);鞘内给予CP55940可显著降低P2X_2受体表达(P0.05),而预先给予AM251可降低CP55940抑制P2X_2受体表达的效应(P0.05)。结论:脊髓背角CB_1受体激活对CCI所致的神经病理性疼痛具有良好的镇痛作用,其镇痛效应可能与抑制CCI大鼠嘌呤能P2X_2受体表达有关。