Walker R F, Sparks D L, Slevin J, Rush M E
J Pineal Res. 1986;3(1):33-40. doi: 10.1111/j.1600-079x.1986.tb00724.x.
The purpose of this study was to examine the temporal effects of norepinephrine (NE) stimulation on pineal serotonin (5HT) in vitro. Rat pineal glands were individually incubated in nutrient media for 6 h. After a 2-h preincubation, the glands were exposed to tryptophan (TRYP) or TRYP + norepinephrine (10(-4)M each) for 4 additional h. Media and pineals were then analyzed for 5HT and 5HIAA content. Initial exposure to TRYP increased 5HT levels in the media. Norepinephrine increased media 5HT concentrations further and also caused 5HIAA levels to rise significantly. These findings suggest that 5HT secretion and/or oxidation is an early response to stimulation of the pineal gland by NE. Following prolonged NE exposure, media 5HT declined to control values while 5HIAA remained high. Similarly, intrapineal levels of 5HT fell after prolonged stimulation with NE. Thus, pineal responses to initial and continued stimulation with NE are differentiable as early and late effects upon 5HT. Early effects may include secretion and/or oxidation of 5HT followed later by utilization of 5HT in N-acetylation pathways such as that leading to melatonin synthesis. The finding that 5HT is secreted in response to NE suggests that the indoleamine may be a hormone of the pineal gland. Based upon its known influence on physiologic rhythms, daily secretion of 5HT from the pineal may be an important part of the gland's time-keeping function.
本研究的目的是检测去甲肾上腺素（NE）刺激对体外培养的松果体血清素（5HT）的时间效应。将大鼠松果体分别在营养培养基中孵育6小时。预孵育2小时后，将松果体再暴露于色氨酸（TRYP）或TRYP + 去甲肾上腺素（各10⁻⁴M）中4小时。然后分析培养基和松果体中的5HT和5HIAA含量。最初暴露于TRYP可增加培养基中的5HT水平。去甲肾上腺素进一步提高了培养基中5HT的浓度，还导致5HIAA水平显著升高。这些发现表明，5HT的分泌和/或氧化是NE刺激松果体的早期反应。在长时间暴露于NE后，培养基中的5HT降至对照值，而5HIAA仍保持较高水平。同样，用NE长时间刺激后，松果体内的5HT水平下降。因此，松果体对NE初始和持续刺激的反应可区分为对5HT的早期和晚期效应。早期效应可能包括5HT的分泌和/或氧化，随后是5HT在N - 乙酰化途径（如导致褪黑素合成的途径）中的利用。5HT响应NE分泌的发现表明，吲哚胺可能是松果体的一种激素。基于其对生理节律的已知影响，松果体每日分泌5HT可能是该腺体计时功能的重要组成部分。
