抗乙酰胆碱受体单链抗体基因克隆与表达

目的重建含有抗乙酰胆碱受体(AChR)单链抗体1929#(single-chain Fv antibody 1929#,scFv1929#)基因的载体并在大肠杆菌(E.coli)进行表达,提高scFv1929#的可溶性表达量。方法用聚合酶链反应法(PCR)扩增载体pHEN1中的scFv1929#结构基因,将扩增产物定向克隆至载体pET32a(+)的多克隆位点中构建新的载体pET32a(+)-scFv1929#,经EcoR v和NotⅠ双酶切后进行鉴定,并将所构建载体转化入表达宿主E.coli BL21(DE3)plysS菌株内诱导表达后集菌并裂菌,将诱导前菌体、诱导后菌体,以及裂菌后所得诱导后上清、诱导后沉淀进行十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)分析,并采用Western blot(WB)法进行鉴定。结果鉴定结果显示载体pET32a(+)-scFv1929#中所插入的scFv1929#基因片段大小为730bp,与预计相符,经测序确定该基因序列无误。SDS-PAGE电泳结果显示37℃下诱导前菌体、诱导后菌体、诱导后上清、诱导后沉淀中均可在相对分子质量(Mr)接近44 000处见到蛋白条带,其中诱导后菌体及诱导后沉淀中的条带较粗大。经WB法证实融合蛋白scFv1929#具有较高特异性。结论 scFv1929#表达载体pET32a(+)-scFv1929#被成功构建,并可在大肠杆菌中高效表达,其表达产物具有较好特异性。     

Adolescent Intermittent Ethanol Exposure Is Associated with Increased Risky Choice and Decreased Dopaminergic and Cholinergic Neuron Markers in Adult Rats

Background:

Binge drinking is prevalent during adolescence and may have effects on the adult brain and behavior. The present study investigated whether adolescent intermittent ethanol exposure alters adult risky choice and prefrontal dopaminergic and forebrain cholinergic neuronal marker levels in male Wistar rats.

Methods:

Adolescent (postnatal day 28–53) rats were administered 5g/kg of 25% (vol/vol) ethanol 3 times/d in a 2-days–on/2-days–off exposure pattern. In adulthood, risky choice was assessed in the probability discounting task with descending and ascending series of large reward probabilities and after acute ethanol challenge. Immunohistochemical analyses assessed tyrosine hydroxylase, a marker of dopamine and norepinephrine in the prelimbic and infralimbic cortices, and choline acetyltransferase, a marker of cholinergic neurons, in the basal forebrain.

Results:

All of the rats preferred the large reward when it was delivered with high probability. When the large reward became unlikely, control rats preferred the smaller, safe reward, whereas adolescent intermittent ethanol-exposed rats continued to prefer the risky alternative. Acute ethanol had no effect on risky choice in either group of rats. Tyrosine hydroxylase (prelimbic cortex only) and choline acetyltransferase immunoreactivity levels were decreased in adolescent intermittent ethanol-exposed rats compared with controls. Risky choice was negatively correlated with choline acetyltransferase, implicating decreased forebrain cholinergic activity in risky choice.

Conclusions:

The decreases in tyrosine hydroxylase and choline acetyltransferase immunoreactivity suggest that adolescent intermittent ethanol exposure has enduring neural effects that may lead to altered adult behaviors, such as increased risky decision making. In humans, increased risky decision making could lead to maladaptive, potentially harmful consequences.     

Pharmacology of Ultrasonic Vocalizations in adult Rats: Significance,Call Classification and Neural Substrate

Pharmacological studies of emotional arousal and initiation of emotional states in rats measured by their ultrasonic vocalizations are reviewed. It is postulated that emission of vocalizations is an inseparable feature of emotional states and it evolved from mother-infant interaction. Positive emotional states are associated with emission of 50 kHz vocalizations that could be induced by rewarding situations and dopaminergic activation of the nucleus accumbens and are mediated by D1, D2, and partially D3 dopamine receptors. Three biologically significant subtypes of 50 kHz vocalizations have been identified, all expressing positive emotional states: (1) flat calls without frequency modulation that serve as contact calls during social interactions; (2) frequencymodulated calls without trills that signal rewarding and significantly motivated situation; and (3) frequency-modulated calls with trills or trills themselves that are emitted in highly emotional situations associated with intensive affective state. Negative emotional states are associated with emission of 22 kHz vocalizations that could be induced by aversive situations, muscarinic cholinergic activation of limbic areas of medial diencephalon and forebrain, and are mediated by M2 muscarinic receptors. Two biologically significant subtypes of 22 kHz vocalizations have been identified, both expressing negative emotional sates: (1) long calls that serve as alarm calls and signal external danger; and (2) short calls that express a state of discomfort without external danger. The positive and negative states with emission of vocalizations are initiated by two ascending reticular activating subsystems: the mesolimbic dopaminergic subsystem as a specific positive arousal system, and the mesolimbic cholinergic subsystem as a specific negative arousal system.     

The Role of Muscarinic Receptors in the Pathophysiology of Mood Disorders: A Potential Novel Treatment?

The central cholinergic system has been implicated in the pathophysiology of mood disorders. An imbalance in central cholinergic neurotransmitter activity has been proposed to contribute to the manic and depressive episodes typical of these disorders. Neuropharmacological studies into the effects of cholinergic agonists and antagonists on mood state have provided considerable support for this hypothesis. Furthermore, recent clinical studies have shown that the pan-CHRM antagonist, scopolamine, produces rapid-acting antidepressant effects in individuals with either major depressive disorder (MDD) or bipolar disorder (BPD), such as bipolar depression, contrasting the delayed therapeutic response of conventional mood stabilisers and antidepressants. This review presents recent data from neuroimaging, post-mortem and genetic studies supporting the involvement of muscarinic cholinergic receptors (CHRMs), particularly CHRM2, in the pathophysiology of MDD and BPD. Thus, novel drugs that selectively target CHRMs with negligible effects in the peripheral nervous system might produce more rapid and robust clinical improvement in patients with BPD and MDD.     

Mammary gland sympathetic innervation is a major component in type 1 deiodinase regulation

Recent observations have shown that in lactating rats previously deprived of suckling, either suckling stimulus or ip injection of norepinephrine was capable of increasing mammary deiodinase type 1 (M-D1) mRNA content and enzyme activity. In the present work, we show that intact efferent sympathetic mammary innervation is required to restore both mammary D1 mRNA content and enzyme activity, whereas suckling-induced secretion of catecholamines from the adrenal glands does not seem to participate in M-D1 enzyme regulation. The data also indicate that the sympathetic reflex activation in response to suckling involves two complementary autonomic components: (1) activation, presumably through mammary segmental arrangement affecting neighboring mammary glands; and (2) an individual reflex regulatory mechanism capable of maintaining M-D1 activity within each mammary gland. In addition to these findings, we show that the suckling-induced sympathetic activation of M-D1 activity could be blocked by prior activation of ductal mechanoreceptors. This set of regulatory and counterregulatory mechanisms seems to ensure the optimal control of mammary energetic expenditure according to litter size.