Cannabidiol, a constituent of Cannabis sativa, modulates sleep in rats

Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and cannabidiol (CBD) are two major constituents of Cannabis sativa. Delta(9)-THC modulates sleep, but no clear evidence on the role of CBD is available. In order to determine the effects of CBD on sleep, it was administered intracerebroventricular (icv) in a dose of 10 microg/5 microl at the beginning of either the lights-on or the lights-off period. We found that CBD administered during the lights-on period increased wakefulness (W) and decreased rapid eye movement sleep (REMS). No changes on sleep were observed during the dark phase. Icv injections of CBD (10 microg/5microl) induced an enhancement of c-Fos expression in waking-related brain areas such as hypothalamus and dorsal raphe nucleus (DRD). Microdialysis in unanesthetized rats was carried out to characterize the effects of icv administration of CBD (10 microg/5 microl) on extracellular levels of dopamine (DA) within the nucleus accumbens. CBD induced an increase in DA release. Finally, in order to test if the waking properties of CBD could be blocked by the sleep-inducing endocannabinoid anandamide (ANA), animals received ANA (10 microg/2.5 microl, icv) followed 15 min later by CBD (10 microg/2.5 microl). Results showed that the waking properties of CBD were not blocked by ANA. In conclusion, we found that CBD modulates waking via activation of neurons in the hypothalamus and DRD. Both regions are apparently involved in the generation of alertness. Also, CBD increases DA levels as measured by microdialysis and HPLC procedures. Since CBD induces alertness, it might be of therapeutic value in sleep disorders such as excessive somnolence.     

Dopamine and the Dopamine Oxidation Product 5,6-Dihydroxylindole Promote Distinct On-Pathway and Off-Pathway Aggregation of α-Synuclein in a pH-Dependent Manner

The deposition of α-synuclein (α-syn) aggregates in dopaminergic neurons is a key feature of Parkinson's disease. While dopamine (DA) can modulate α-syn aggregation, it is unclear which other factors can regulate the actions of DA on α-syn. In this study, we investigated the effect of solution conditions (buffer, salt and pH) on the oligomerization of α-syn by DA. We show that α-syn oligomerization is dependent on the oxidation of DA into reactive intermediates. Under acidic pH conditions, DA is stable, and DA-mediated oligomerization of α-syn is inhibited. From pH 7.0 to pH 11.0, DA is unstable and undergoes redox reactions, promoting the formation of SDS-resistant soluble oligomers of α-syn. We show that the reactive intermediate 5,6-dihydroxylindole mediates the formation of α-syn soluble oligomers under physiological conditions (pH 7.4). In contrast, under acidic conditions (pH 4.0), 5,6-dihydroxylindole promotes the formation of SDS-resistant insoluble oligomers that further associate to form sheet-like fibrils with β-sheet structure that do not bind the dye thioflavin T. These results suggest that distinct reactive intermediates of DA, and not DA itself, interact with α-syn to generate the α-syn aggregates implicated in Parkinson's disease.     

Effect of storage on amnesic shellfish poisoning (ASP) toxins in king scallops (Pecten maximus)

Since 1998, king scallops (Pecten maximus) obtained from Scottish offshore sites have been monitored for domoic acid (DA) and epi-domoic acid (epi-DA), the principal toxic compounds associated with amnesic shellfish poisoning (ASP). The presence of these toxins in king scallops harvested from Scottish waters at concentrations exceeding the current regulatory limit (20 μg g⁻¹ shellfish flesh) is a recurrent event. However, little information was available to determine the effects that different storage conditions experienced during sample transportation to the monitoring laboratory may have on the toxin concentrations, which are subsequently detected. Furthermore, the stability of DA and epi-DA in the solvents (methanol:water (1:1, v/v) and citric acid buffer (0.5 M, pH 3.2)) routinely used for their extraction from shellfish has not previously been assessed. Results from this study demonstrate that when king scallop samples were stored for 2–3 days at 12 °C, a significantly higher toxin concentration was detected in the gonad than when samples were stored at 4 °C and analysed within 48 h. This implies that monitoring programmes must consider transport and storage conditions between harvest and analysis. Stability studies showed rapid decomposition of DA and epi-DA in aqueous methanol extracts while DA and epi-DA seem acceptably stable when stored refrigerated in citrate buffer.     

Nicotinic receptor alpha7-subunits are coupled to the stimulation of nitric oxide synthase in rat dorsal root ganglion neurons

In dorsal root ganglia (DRG) intraganglionic communication takes place both among neurons and between neurons and satellite cells. One diffusible substance involved in this signalling is nitric oxide (NO), and acetylcholine (ACh) is a candidate for the stimulation of intraganglionic NO synthesis. DRG neurons react to ACh-receptor stimulation with NO-dependent cGMP production. Here, we investigated the role of the 7-subunit containing Ca²⁺-permeable nicotinic ACh receptors (nAChR) in this process. The 7-nAChR mRNA and the protein were expressed in virtually all lumbar DRG neurons as evidenced by laser-assisted cell picking and oligo cell RT-PCR, in situ hybridisation and immunohistochemistry. Strong 7-nAChR immunoreactivity was present in vanilloid receptor 1-immunoreactive, i.e. nociceptive, neurons. A neuronal production of NO in response to nicotine could be demonstrated in DRG slice preparations utilising the NO-sensitive fluorescent indicator diaminofluorescein diacetate (DAF-2DA). This stimulation of NO production was sensitive to inhibition of 7-nAChR by mecamylamine and -bungarotoxin, to inhibition of nitric oxide synthase (NOS) with L-NAME and L-NMMA, and to the blockade of voltage-operated Ca²⁺ channels by verapamil. The results show the presence of the 7-nAChR subunit in nociceptive rat DRG neurons and provide evidence for its coupling to NOS activation, indicating a role of this pathway in the intraganglionic communication in sensory ganglia.     

Effect of organotin compounds and hexachlorophene on brain adenosine cyclic 3',5'-monophosphate metabolism.

The effect of triethyltin (TET), triphenyltin (TPT), hexachlorophene (HCP) and cuprizone on adenosine cyclic 3',5'-monophosphate (cyclic AMP) production in rat brain was examined both in vitro and in vivo. TET and TPT inhibited basal adenylate cyclase activity of brain homogenate at a concentration as low as 1 microM in vitro but these compounds had no effect on norepinephrine (NE) and dopamine(DA)-stimluated enzyme activity. HCP and cuprizone failed to inhibit adenylate cyclase activity. In vivo TET given intravenously at a dose rate of 10 mg/kg decreased the cyclic AMP content of cerebrum, but not of medulla. TPT and HCP give intravenously and intraperitoneally respectively failed to decrease the cyclic AMP content of the cerebrum. In the case of TET the reduction in cyclic AMP content of the cerebrum was prevented by maintaining the rats normothermic after treatment. On the basis of these results the inhibition of adenylate cyclase produced by TET in brain homogenates in vitro would not appear to be involved in the development of nervous changes associated with acute TET toxicity, or in the production of progressive brain oedema caused by TET, HCP and cuprizone.     

多巴胺对血管平滑肌细胞钙激活钾通道的影响及其机制

目的：研究多巴胺对血管平滑肌细胞大电流、钙激活钾（ＢＫｃａ）通道的影响及其信息传递机制。方法用膜片钳细胞贴附式技术,记录细胞能液内灌流多巴胺受体激动剂、阻断剂以及第二信使及相关蛋白激酶拮机剂对猪冠状动脉血管平滑肌细胞ＢＫｃａ 爱道活动的影响。结果：多巴胺增加ＢＫｃａ通道活性（Ｐ〈０．０１）,并可被ＣＡ－１受体阻断剂ＳＣＨ２３３９０完全阻断,但不受β２受体阻断剂普藉洛尔的影响。腺苷酸环化酶抑制剂ＳＯ     

Genetic control of arthritis in rats

This study was specifically designed to analyse the genetic control of the chronic disease course for the development of arthritis. Arthritis models with a chronic erosive arthritis are collagen induced arthritis induced with homologous collagen in oil but also arthritis induced with certain non-immunogenic adjuvants such as pristane and avridine. In the presently described experiment we have used pristane induced arthritis. A single injection of 150 μl pristane induces severe chronic arthritis in DA rats. The disease mimics rheumatoid arthritis in many aspects such as the chronic disease course, an erosive inflammation of peripheral joints, symmetric involvement of the joints and the development of rheumatoid factors. To determine the genetic contribution we have used a number of inbred, recombinant inbred and congenic strains as well as specifically designed segregating crosses. An influence by the MHC region (designated Pia1 locus) on the chronic disease course was determined through the uses of MHC congenic LEW strains in which the RT1-f haplotype conferred highest susceptibility. To map genes outside of MHC we used an F2 cross between the highly susceptible DA and the resistant E3 strains. Loci exclusively associated with different phenotypes of the disease could be identified:

Arthritis onset (Pia2 and Pia3).

Severity and joint erosions (Pia4).

Chronicity (Pia5 and Pia6) and Pia1 (determined from MHC congenic (strains)

These findings demonstrates that a chronic self-perpetuative disease, mimicking rheumatoid arthritis, is controlled by different set of genes exclusively linked to different phases of the disease course such as arthritis onset, joint erosions, severity and chronicity.     

Mechanism of action of salsolinol on tyrosine hydroxylase

Tyrosine hydroxylase (TH) is the first and rate-limiting enzyme in dopamine synthesis. Dopamine regulates TH as an end-product inhibitor through its binding to a high and low affinity site, the former being abolished by Ser40 phosphorylation only, and the latter able to bind and dissociate according to intracellular dopamine levels. Here, we have investigated TH inhibition by a dopamine metabolite found in dopaminergic brain regions, salsolinol (SAL). SAL is known to decrease dopamine in the nigrostriatal pathway and mediobasal hypothalamus, and to also decrease plasma catecholamines in rat stress models, however a target and mechanism for the effects of SAL have not been found. We found that SAL inhibits TH activity in the nanomolar range in vitro, by binding to both the high and low affinity dopamine binding sites. SAL produces the same level of inhibition as dopamine when TH is non-phosphorylated. However, it produces 3.7-fold greater inhibition of Ser40-phosphorylated TH compared to dopamine by competing more strongly with tetrahydrobiopterin, the cofactor of this enzymatic reaction. SAL’s potent inhibition of phosphorylated TH would prevent TH from being fully activated to synthesise dopamine.     

抑郁症患者儿童期受虐对单胺类神经递质及相关因素的影响

目的：探索抑郁症患者儿童期受虐对血清5．羟色胺（5-hydroxytryptamine5-HT）、多巴胺（Dopamine DA）和去甲肾上腺素（Norepinephrine NE）水平及相关因素的影响。方法：对101例抑郁症患者采用儿童受虐问卷（CTQ）、24项汉密尔顿抑郁量表（HAMD24）、自杀意念量表（SIOSS）及Beck绝望量表（BHS）评定儿童期受虐程度,抑郁严重程度,自杀意念强度和绝望严重程度。采用酶联免疫吸附法（ELLSA）测定血清5-HT、DA和NE水平。根据CTQ评分将总分≥50分,分量表≥10分定为被虐待。结果：（1）情感忽视组血清5-HT和DA水平明显低于无忽视组（35．63±62．43,62．58±79．50;P〈0．05;4．08±6．30ng／1,7．61±11．47ng／1,P〈0．05）,受虐组血清NE水平虽高于无受虐组但无统计学意义;（2）情感受虐组和躯体受虐组的HAMD24评分明显高于无受虐组（30．60±9．84,26．77±6．54P〈0．05;31．00±9．59,27．79±8．23;P〈0．05）．遭受性虐待组SIOSS评分明显高于无虐待组（17．07±3．29,14．26±3．63,P〈0．01）。情感受虐组BHS评分明显高于无受虐组（12．13±3．32,10．35±4．30,P〈0．05）（3）儿童期情感被忽视和躯体被虐待评分与BHS评分呈明显正相关（r=0．22,r=0．23,P〈0．05）,被性虐待程度与SIOSS评分有明显相关（r=0．35,P〈0．01）。结论：儿童期情感被忽视的抑郁症患者血清5-HT和DA水平偏低,儿童期受虐的抑郁症患者可能存在下丘脑-垂体-肾上腺轴的不稳定。儿童期受虐是抑郁发作的危险因素并有更严重的抑郁症状。