Demas Gregory E, Bartness Timothy J, Nelson Randy J, Drazen Deborah L
Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Am J Physiol Regul Integr Comp Physiol. 2003 Oct;285(4):R873-9. doi: 10.1152/ajpregu.00209.2003.
Siberian hamsters (Phodopus sungorus) rely on photoperiod to coordinate seasonally appropriate changes in physiology, including immune function. Immunity is regulated, in part, by the sympathetic nervous system (SNS), although the precise role of the SNS in regulating photoperiodic changes in immunity remains unspecified. The goal of the present study was to examine the contributions of norepinephrine (NE), the predominant neurotransmitter of the SNS, to photoperiodic changes in lymphocyte proliferation. In experiment 1, animals were maintained in long [16:8-h light-dark cycle (16:8 LD)] or short days (8:16 LD) for 10 wk, and splenic NE content was determined. In experiment 2, in vitro splenocyte proliferation in response to mitogenic stimulation (concanavalin A) was assessed in spleen cell suspensions taken from long- or short-day hamsters in which varying concentrations of NE were added to the cultures. In experiment 3, splenocyte proliferation was examined in the presence of NE and selective alpha- and beta-noradrenergic receptor antagonists (phenoxybenzamine and propranolol, respectively) in vitro. Short-day animals had increased splenic NE content compared with long-day animals. Long-day animals had higher proliferation compared with short-day animals independent of NE. NE (1 microM) further suppressed splenocyte proliferation in short but not long days. Last, NE-induced suppression of proliferation in short-day hamsters was blocked by propranolol but not phenoxybenzamine. The present results suggest that NE plays a role in photoperiodic changes in lymphocyte proliferation. Additionally, the data suggest that the effects of NE on proliferation are specific to activation of beta-adrenergic receptors located on splenic tissue. Collectively, these results provide further support that photoperiodic changes in immunity are influenced by changes in SNS activity.
西伯利亚仓鼠（Phodopus sungorus）依靠光周期来协调包括免疫功能在内的季节性生理变化。免疫系统部分受交感神经系统（SNS）调节，尽管SNS在调节免疫光周期变化中的具体作用尚不清楚。本研究的目的是检验去甲肾上腺素（NE）（SNS的主要神经递质）对淋巴细胞增殖光周期变化的作用。在实验1中，将动物饲养在长日照[16:8小时明暗循环（16:8 LD）]或短日照（8:16 LD）条件下10周，然后测定脾脏NE含量。在实验2中，对来自长日照或短日照仓鼠的脾细胞悬液进行体外脾细胞增殖实验，实验中向培养物中添加不同浓度的NE以响应促有丝分裂刺激（伴刀豆球蛋白A）。在实验3中，在体外存在NE以及选择性α和β肾上腺素能受体拮抗剂（分别为酚苄明和普萘洛尔）的情况下检测脾细胞增殖。与长日照动物相比，短日照动物的脾脏NE含量增加。与短日照动物相比，长日照动物的增殖水平更高，且与NE无关。NE（1 microM）进一步抑制短日照而非长日照条件下的脾细胞增殖。最后，普萘洛尔可阻断NE诱导的短日照仓鼠增殖抑制，而酚苄明则不能。目前的结果表明，NE在淋巴细胞增殖的光周期变化中发挥作用。此外，数据表明NE对增殖的影响特定于脾脏组织上β肾上腺素能受体的激活。总体而言，这些结果进一步支持了免疫的光周期变化受SNS活动变化影响的观点。
