Anatomical and behavioral impact of a lentiviral tool tapping onto hippocampal serotonin reuptake in rats

We aimed at the further characterization of rats in which SERT gene silencing was achieved by hippocampal injection of a lentiviral vector, carrying three si-RNA to block SERT mRNA at 66% of normal levels. Improved self-control and reduced restlessness were already demonstrated in these rats. Present further studies consisted of male adult rats, bilaterally inoculated within the hippocampus; control rats received lentivirus particles inactivated with heat. Both groups were maintained in isolation for 5 months, starting from inoculation. Neurochemical changes were studied by proton magnetic resonance spectroscopy (1H-MRS): we found increased hippocampal viability and bioenergetic potential; however, rats showed a behaviorally depressive pattern, also characterized by enhanced affiliation. Based on the extent of such effects, the whole lenti-SERT group was divided into two subgroups, termed intermediate- and extreme- phenotype profiles. While all rats had a widespread modification within dorsal/ventral striatum, amygdala, and hypothalamus, only the former subgroup showed an involvement of Raphé medialis, while, for the latter subgroup, an increase of SERT within hippocampus was unexpectedly caused. Within the less-affected “intermediate” rats, hippocampal 5-HT7 receptors were down-modulated, and also similarly within substantia nigra, septum, and neocortex. This picture demonstrates that additional rather than fewer neurobiological changes accompany a lower phenotypic expression. Overall, tapping hippocampal SERT affected the balance between habits versus strategies of coping by promoting morphogenetic processes indicative of a serotonergic fiber plasticity. Supplementary studies about serotonergic dynamics and neurogenesis within fronto-striatal circuits are needed.     

Prenatal stress‐related alterations in synaptic transmission and 5‐HT7 receptor‐mediated effects in the rat dorsal raphe nucleus are ameliorated by the 5‐HT7 receptor antagonist SB 269970

Early life adversity exerts a detrimental influence on developing brain neuronal networks and its consequences may include mental health disorders. In rats, prenatal stress may lead to anxiety and depressive‐like behavior in the offspring. Several lines of evidence implicated an involvement of prenatal stress in alterations of the brain serotonergic system functions, but the effects of prenatal stress on its core, the dorsal raphe nucleus (DRN), still remain incompletely understood. The present study was aimed at finding whether prenatal stress induces modifications in the glutamatergic and GABAergic inputs to DRN projection cells and whether it affects DRN 5‐HT₇ receptors, which modulate activity of these synapses. Prenatal stress resulted in an increase in basal frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and in a decrease in basal frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) recorded from putative projection neurons in DRN slices ex vivo. While there were no changes in the excitability of DRN projection neurons, the 5‐HT₇ receptor‐mediated reduction in the sEPSC frequency and rise in the sIPSC frequency, seen in control rats, were largely absent in slices obtained from prenatally stressed rats. Repeated administration of SB 269970, a 5‐HT₇ receptor antagonist, resulted in a reversal of prenatal stress‐induced alterations in 5‐HT₇ receptor‐mediated effects on the sEPSC/sIPSC frequency. Moreover, the treatment reversed prenatal stress‐induced alterations in basal excitatory transmission and partially reversed the effect of stress on basal inhibitory transmission in the DRN.     

5-羟色胺2A、2C受体基因多态性与难治性抑郁症的关联分析

目的：探讨中国汉族人群难治性抑郁症患者5-羟色胺2C（5-HT2C）受体基因与5-HT2A受体基因之间的关联性。方法：应用聚合酶链式反应（PCR）扩增技术及限制性片段长度多态性（RFLP）分别测定77例难治性抑郁症患者及90名正常人5-HT2C受体基因和5-HT2A受体基因的基因型和等位基因。结果：难治性抑郁症组-759野生型频率明显低于对照组。-759野生型／-697野生型频率也显著低于正常;患者组5-HT2A受体基因型杂合子组的-759野生型、-697野生型以及-759野生型／-697野生型均明显高于纯合子组。结论：-759野生型可能与难治性抑郁症的发病存在一定的相关性;5-HT2A受体基因与5-HT2C受体基因相互之间对难治性抑郁症易患性可能存在一定的关系。     

The biology of Nociceptin/Orphanin FQ (N/OFQ) related to obesity,stress, anxiety,mood, and drug dependence

Nociceptin/Orphanin FQ (N/OFQ) is a 17 amino acid peptide that was deorphanized in 1995. The generation of specific agonists, antagonists and receptor deficient mice and rats has enabled progress in elucidating the biological functions of N/OFQ. Additionally, radio-imaging technologies have been advanced for investigation of this system in animals and humans. Together with traditional neurobehavioral techniques, these tools have been utilized to identify the biological significance of the N/OFQ system and its interacting partners. The present review focuses on the role of N/OFQ in the regulation of feeding, body weight homeostasis, stress, the stress-related psychiatric disorders of depression and anxiety, and in drug and alcohol dependence. Critical evaluation of the current scientific preclinical literature suggests that small molecule modulators of nociceptin opioid peptide receptors (NOP) might be useful in the treatment of diseases related to these biological functions. In particular, the literature data suggest that antagonism of NOP receptors will produce anti-obesity and antidepressant activities in humans. However, there are also contradictory data discussed. The current literature on the role of N/OFQ in anxiety and addiction, on the other hand points primarily to a role of agonist modulation being potentially therapeutic. Some drug-like molecules that function either as agonists or antagonists of NOP receptors have been optimized for human clinical study to test some of these hypotheses. The discovery of PET ligands for NOP receptors, combined with the pharmacological tools and burgeoning preclinical data set discussed here bodes well for a rapid advancement of clinical understanding and potential therapeutic benefit.     

Altered vasoactive intestinal polypeptide gene expression in the fetal rat suprachiasmatic nucleus following prenatal serotonin deficiency

This study has evaluated the possible role of serotonin, a potential morphogen, in the regulation of vasoactive intestinal polypeptide (VIP) gene expression in the target neurons of the suprachiasmatic nucleus (SCN) before and after the onset of the serotonin neurotransmitter function. VIP gene expression was quantified by in situ hybridization of the corresponding mRNA on cryostat sections with subsequent film autoradiography and densitometry. The content of VIP mRNA was measured in the SCN in fetuses at the 21st embryonic day (E21) and in postnatal rats at day 11 (P11) following chronic depletion of serotonin by p-chlorophenylalanine, an inhibitor of serotonin synthesis. This inhibitor was daily injected to pregnant rats for E13–20 or to postnatal animals for P2–10. Results of this study indicate that prenatal serotonin depletion caused a significant increase in VIP mRNA content in the SCN compared to control fetuses. On the contrary, the same treatment performed postnatally did not change VIP mRNA levels in the SCN. These data suggest that the VIP gene expression in differentiating target neurons of the SCN might be under serotonin inhibitory control during prenatal neurogenesis, prior to the onset of the serotoninergic neurotransmission.     

递质受体相关候选基因与强迫谱系障碍

目的:了解多巴胺D2受体(DRD2)基因、D3受体(DRD3)基因、D4受体(DRD4)基因、多巴胺转运体(DAT1)基因、儿茶酚胺氧位甲基转移酶(COMT)基因、5-羟色胺2A受体(5-HTR2A)基因、5-羟色胺转运体(5-HTT)基因等与强迫谱系障碍(OCSDs)的连锁关系。方法:选取一个连续3代发病的强迫谱系障碍家系,共20名,量表采用遗传研究诊断问卷(DIGS)及遗传研究家族问卷(FIGS)。采集该家系中12个正常个体,8个受累个体的血样,选取DRD2、DRD3、DRD4、DAT1、COMT、5-HTR2A、5-HTT基因附近27对微卫星标记引物,采用两点和多点非参数分析的方法对该家系进行连锁分析。结果:27对微卫星标记位点的两点和多点非参数分析LOD值(NPL值)均未达到验证性连锁的阈值(NPL=1.2)。结论:未能验证DRD2、DRD3、DRD4、DAT1、COMT、5-HTR2A、5-HTT基因与OCSDs的连锁关系,但亦不能排除这些基因与OCSDs的相关性。