5-HT transporter function: Interaction of hormones and antidepressants

描述(由申请人提供)： 一些女性患严重抑郁障碍(MDD)的脆弱性与荷尔蒙波动有关。性腺激素的作用可能有助于MDD的发展(以及产后抑郁症)，这可能是MDD在女性中比在男性中更常见的部分原因。尽管如此，研究抗抑郁药物，特别是选择性5-羟色胺再摄取抑制剂(SSRI)对行为或神经化学参数影响的临床前研究主要是男性受试者。在我们的实验中，观察了SSRIs对雌性大鼠的影响。使用体内计时安培技术发现，系统地或局部地将卵巢激素(苯甲酸雌二醇(EB)或孕酮(P))急性注射到海马CA3区，会干扰SSRI抑制其大脑中最初的细胞靶标--5-羟色胺转运体(SERT)--功能的能力。此外，EB而不是P阻断了SERT的功能。此外，在调节雌二醇的这两种作用的机制上(S)似乎有一些不同。此外，EB的这两种作用预计将对雌二醇或雌二醇加孕酮的能力产生抵消作用，当与此类治疗结合使用时，雌二醇和孕酮可提高SSRIs的疗效。有证据表明，雌激素的这些作用是通过膜和核雌激素受体(ER)的激活来实现的。相比之下，黄体酮的作用似乎主要是由核受体介导的。这些先前的结果为当前提案中的研究提供了理论基础，其主要目标是使用神经化学或行为措施来扩展这些研究，看看是否可以获得进一步的证据，表明女性性激素治疗要么影响SERT功能，要么干扰SSRI抑制SERT的能力。实验将在去卵巢的雌性大鼠身上进行。将使用的新技术是体内微透析和强迫游泳试验(FST)。我们的假设是，雌激素或孕酮的急性治疗将阻断局部应用氟伏沙明的能力，即提高海马区细胞外5-羟色胺水平的能力，或其减少不动或增加FST游泳行为的能力。此外，为了研究激素效应的可能机制：(1)在突触体膜上进行生物素化研究，以检测激素处理后SERT的质膜分布；(2)利用计时电流法，将使用两种方法，即使用特定的雌激素受体(ER1或ER2)基因敲除小鼠和选择性雌激素受体激动剂在大鼠体内的作用，以研究这些雌激素受体亚型在调节雌激素效应中的作用；再次使用计时电流法(3)将通过使用脑源性神经营养因子受体的拮抗剂来研究作为中介的脑源性神经营养因子可能参与雌二醇对SSRI的作用。最后，我们将研究长期、临床上更合适的单独使用E2或E2+P治疗是否会改变SSRI的SERT功能和/或长期给药产生的影响。 公共卫生相关性： 随着最近在伊拉克和阿富汗的战斗部署，治疗退伍军人的精神卫生保健需求在未来几年将是一个持续的挑战。据估计，25%至30%的伊拉克和阿富汗战争退伍军人报告有精神障碍或认知功能障碍的症状(Seal等人。2007)。在过去的一年里，女性退伍军人经历严重抑郁发作的可能性是男性的两倍。帕蒂·默里参议员介绍了2008年《女退伍军人保健改进法案》(S.2799)，这进一步证明了妇女在军队中的作用越来越大。这项立法的要求将包括对在伊拉克现役的女退伍军人的健康进行长期研究，评估退伍军人制度中妇女保健的障碍，以及为护理遭受性创伤和创伤后应激障碍的妇女的提供者提供培训。我们的基础研究可能对MDD和/或PTSD患者具有治疗意义。

DESCRIPTION (provided by applicant): The vulnerability of some women to develop major depressive disorder (MDD) is associated with hormonal fluctuations. It is likely that effects of gonadal hormones contribute to the development of MDD (as well as postpartum depression) and this may be part of the reason why MDD is more common in females than in males. In spite of this, preclinical research examining the effects of antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs)- the drug class of choice for the treatment of MDD- on either behavioral or neurochemical parameters, have mainly used male subjects. In our experiments, effects of SSRIs in female rats were examined. It was found, using the technique of in vivo chronoamperometry, that acute administration of ovarian hormones (estradiol benzoate (EB) or progesterone (P)), either given systemically or locally into the CA3 region of the hippocampus, interferes with the ability of SSRIs to inhibit the function of what is widely considered their initial cellular target in brain- the serotonin transporter (SERT). In addition, EB but not P blocked the function of the SERT. Further, there appears to be some difference in the mechanism(s) mediating these two effects of estradiol. Further, these two effects of EB would be expected to exert counteracting effects on the ability of estradiol, or estradiol plus progesterone, to improve the efficacy of SSRIs when given in combination with such treatment. Evidence was obtained that these effects of estradiol are mediated via activation of membrane as well as nuclear estrogen receptors (ER). By contrast, the effect of progesterone seems to be mediated primarily by nuclear receptors. These previous results provide the rationale for the studies in the current proposal, whose principal goal is to extend these studies using neurochemical or behavioral measures to see if further evidence can be obtained that treatment with female sex hormones either influences SERT function and/or interferes with the ability of SSRIs to inhibit the SERT. Experiments will be carried out in ovariectomized female rats. The new techniques to be used are in vivo microdialysis and the forced swimming test (FST). Our hypotheses are that acute treatment with either estradiol or progesterone will block the ability of locally applied fluvoxamine, an SSRI, either to elevate extracellular levels of serotonin in the hippocampus or its ability to decrease immobility or increase swimming behavior in the FST. In addition, to examine possible mechanisms underlying the hormonal effects: (1) biotinylation studies on synaptosomal membranes will be carried out to examine the plasma membrane distribution of the SERT after hormone treatment; (2) using chronoamperometry, two approaches will be used, namely the use of specific estrogen receptor (ER1 or ER2) knockout mice and the effects of selective estrogen receptor agonists in rats, to study the role of these estrogen receptor subtypes in mediating the effects of estrogen; and again using chronoamperometry (3) the possible involvement of brain-derived neurotrophic factor (BDNF) as an intermediary in the effect of estradiol on the action of an SSRI will be examined by using an antagonist of the receptor for BDNF. Finally, we will investigate if longer-term, more clinically appropriate treatment with E2 alone or E2+P alters SERT function and/or effects produced by an SSRI given chronically. PUBLIC HEALTH RELEVANCE: With the recent combat deployments in Iraq and Afghanistan, treating the mental health care needs of veterans will be a continuing challenge for years to come. An estimated 25 to 30% of veterans of the wars in Iraq and Afghanistan have reported symptoms of a mental disorder or cognitive dysfunction (Seal et al. 2007). Female veterans were twice as likely as their male counterparts to have experienced a major depressive episode in the last year. Further evidence of the increasing role of women in the military is exemplified by Senator Patty Murray introducing the Women Veterans Health Care Improvement Act of 2008 (S. 2799). Requirements of the legislation would include a long-term study on the health of women veterans who served on active duty in Iraq, an assessment of barriers to health care for women in the VA system, and training for providers on the care of women who have suffered sexual trauma and those with PTSD. Our basic research studies could have treatment implications for patients with either MDD and/or PTSD.