Determining the biological basis for phenotypic sex differences in kappa opioid receptor function

κ阿片受体（KOR）是脊椎动物中四种相关阿片受体蛋白之一。KOR激动剂既镇痛又烦躁。我以前已经表明，一部分KOR镇痛是由于参与烦躁不安的途径，导致应激诱导的镇痛。因此，全身KOR镇痛是由这些镇痛和应激途径的会聚介导的。KOR系统也值得注意的是一个突出的性别差异，其中女性显着低于男性镇痛。目前尚不清楚在KOR激动剂的应激效应中是否存在类似的性别二分法，以及这可能如何影响KOR镇痛。性二型性状可能是由于性腺激素（睾酮或雌激素）的影响或X或Y染色体上表达的基因的互补。历史上，切除性腺（睾丸或卵巢）被用来检查性别差异。然而，这种方法无法揭示性染色体上表达的基因的影响，因为性染色体只在其相应的性腺中表达（X与卵巢，Y与睾丸）。为了克服这一局限性，我采用了两种创新的遗传方法来操纵性染色体的表达与性腺激素。我测试的假设，女性表现出较低的KOR介导的镇痛由于X染色体基因介导的应激反应的差异。 对于第一个目标，我测试的假设，即KOR镇痛的差异是由于压力反应的差异，通过使用各种行为测试的疼痛和焦虑结合药理学操纵的压力反应。在第二个目标中，我将使用转基因小鼠模型来分离和评估性腺激素和性染色体在介导这些性别差异中的贡献。这些模型通过性腺操纵X和Y染色体的表达（即：产生具有睾丸的XX小鼠和具有卵巢的XY小鼠）。这个强大的工具使我能够同时测试性腺激素和性染色体对观察到的性别差异的影响。 现在人们普遍认为，正常和病理性的大脑功能表现出重要的，但知之甚少的性别差异。本研究直接解决了这个问题，通过检查的神经生物学基础的差异，在KOR功能的男性和女性之间。从这些实验中获得的见解可以用来阐明男性和女性在压力和疼痛处理方面的根本差异。这些信息不仅将提高我们对女性基本神经生物学的理解，而且将促进未来男女疼痛和镇痛疗法的发展。最后，这项研究计划将使我能够为这些遗传模型建立育种群体，从而将我的实验室定位为一个精英培训环境，研究许多表型模式中性别差异的机制基础。

The kappa opioid receptor (KOR) is one of four related opioid receptor proteins in vertebrates. KOR agonists are both analgesic and dysphoric. I have shown previously that a portion of KOR analgesia is due to engagement of dysphoric pathways leading to stress-induced analgesia. Therefore, systemic KOR analgesia is mediated by a convergence of these analgesic and stress pathways. The KOR system is also notable for a prominent sex-difference, where females show significantly less analgesia than males. It is unknown if a similar sexual dichotomy exists in the stress effects of KOR agonists, and how this might impact KOR analgesia. Sexually dimorphic traits can be due to either the influence of gonadal hormones (testosterone or estrogen) or the complement of genes expressed on the X or Y chromosome. Historically, removal of the gonads (testes or ovaries) has been used to examine sex differences. However, the influence of genes expressed on the sex chromosomes cannot be revealed by this approach, because the sex chromosomes are only ever expressed with their appropriate gonad (X with ovaries, Y with testes). To overcome this limitation, I employ two innovative genetic approaches to manipulate the expression of sex chromosome with gonadal hormones. I test the hypothesis that females exhibit lower KOR-mediated analgesia due to differences in the stress response mediated by X chromosome genes. For the first aim, I test the hypothesis that differences in KOR analgesia are due to differences in stress response by using a variety of behavioral tests of pain and anxiety in combination with pharmacological manipulation of the stress response. In the second aim, I will use transgenic mouse models to isolate and assess the contribution of gonadal hormones and sex chromosomes in mediating these sex differences. These models manipulate the expression of X and Y chromosomes with the gonads (i.e: generate XX mice with testes and XY mice with ovaries). This powerful tool allows me to test, simultaneously, the impact of gonadal hormones and sex chromosomes on the observed sex difference. It is now widely accepted that normal and pathological brain function exhibits important yet poorly understood sex differences. This study directly addresses this issue by examining the neurobiological basis for the difference in KOR function between males and females. Insights gleaned from these experiments can be used to illuminate fundamental differences in stress and pain processing between males and females. Not only will this information improve our understanding of basic neurobiology in females, but will improve the development of future therapies for pain and analgesia in both sexes. Finally, this research program will allow me to establish breeding colonies for these genetic models, thus positioning my lab to be a an elite training environment examining the mechanistic basis for sex differences across many phenotypic modalities.