Similarity between the effects of suprachiasmatic nuclei lesions and of pinealectomy on gonadotropin release in ovariectomized,sulpiride-treated and melatonin-replaced rats

The aim of this study was to compare the effects of pineal indole treatments on LH and FSH release in pinealectomized and suprachiasmatic lesioned and ovariectomized rats rendered hyperprolactinemic by acute sulpiride treatment. pinealectomy or suprachiasmatic nuclei lesions in female rats both decreased plasma LH and FHS at 10, but not at 20 d after surgery, whereas the daily afternoon administration of melatonin effectively restored levels of both gonadotropins to control values. In ovariectomized rats, pinealectomy or suprachiasmatic nuclei lesions were ineffective in counteracting the high plasma levels of LH and FSH. However, sulpiride treatment in both pinealectomized and suprachiasmatic nuclei lesioned and castrated female rats significantly decreased the levels of LH and FSH, an effect which was counteracted by daily afternoon melatonin administration. Other pineal indoles tested, i.e., 5-hydroxy- and 5-methoxytryptophol, were ineffective in regulating gonadotropin levels. The results suggest that the pineal gland, through its hormone melatonin, can modulate gonadotropin secretion by acting on a dopamine mechanism independent of hypothalamic suprachiasmatic areas.     

云南主栽核桃品种功能成分综合评价

【目的】分析云南主栽核桃品种的功能活性成分差异,为云南核桃深加工提供理论依据。【方法】采用索氏提取仪、凯氏定氮仪、原子吸收光谱仪及荧光检测仪对云南省32个品种核桃果仁试样中粗脂肪含量、粗蛋白含量等10个指标进行主成分分析。【结果】第1主成分的贡献率较高,为27.597%,其中烟酰胺有较大的特征正向量值,Zn和Fe有较大的负向量值; 第2主成分的贡献率为22.562%,其中Ca和粗蛋白含量有较大的正向量值; 第3主成分的贡献率为14.192%,其中粗蛋白含量有较大的正向量值,维生素B₆有较大的负向量值; 第4主成分贡献率为10.582%,褪黑素含有较大的负向量; 前4个主成分的累积贡献率达到74.915%,说明前4个主成分基本概括核桃果仁中10个指标的主要信息。【结论】 云南主栽区核桃品种营养成分的综合评价为:‘云新64’>‘漾濞漾泡’>‘云新4-3’>‘鲁甸大麻2号’>‘云新云岭34号’>‘云新303’>‘云新36’>‘华宁大砂壳’>‘华宁大白壳’>‘云新306’>‘鲁甸大麻1号’>‘保山细香’>‘云新301’>‘永11’>‘云南小圆菠萝’>‘云新高原14’>‘云南大圆菠萝’>‘永泡1号’>‘大姚三台’>‘漾濞娘青’。云南不同地区及海拔漾泡核桃营养成分的综合评价为:‘迪庆漾泡’>‘双江漾泡’>‘漾濞’(1 902 m)>‘景东漾泡’>‘漾濞’(1 734 m)>‘漾濞’(2 563 m)>‘大理永平’>‘临沧漾泡’>‘漾濞’(2 300 m)>‘漾濞’(2 162 m)。     

A novel interplay between membrane and nuclear melatonin receptors in human lymphocytes: significance in IL-2 production

Human lymphocyte melatonin, through membrane and nuclear receptors binding, acts as an activator in IL-2 production. Antagonism of membrane melatonin receptors using luzindole exacerbates the drop of the IL-2 production induced by PGE₂ in peripheral blood mononuclear and Jurkat cells. This paper studies the melatonin membrane and nuclear receptors interplay in PGE₂-diminished IL-2 production. The decrease in IL-2 production after PGE₂ and/or luzindole administration correlated with downregulation in the nuclear receptor RORα. We also highlighted a role of cAMP in the pathway, because forskolin mimicked the effects of luzindole and/or PGE₂ in the RORα expression. Finally, a significant RORα downregulation was observed in T cells permanently transfected with inducible MT₁ antisense. In conclusion, we show a novel connection between melatonin membrane receptor signalling and RORα expression, opening a new way to understand melatonin regulation in lymphocyte physiology. Received 23 September 2008; received after revision 19 November 2008; accepted 21 November 2008     

Aging alters resynchronization of the circadian system in rats after a shift of the light-dark cycle

Summary Four days following an 8-h advance of the light-dark cycle, the circadian rhythms in the pineal N-acetyltransferase activity and melatonin content reappeared in 7-week-old rats, but were still abolished in 24-month-old animals.     

Lesions in suprachiasmatic nuclei simulate effects of pinealectomy on prolactin release in ovariectomized and sulpiride-treated female rats

Summary Previous studies indicate that the pineal gland alters prolactin secretion, and it was suggested that at least part of the effect of the pineal hormone melatonin on prolactin release may be mediated by the hypothalamic structures. In this study, pinealectomy and lesions of the suprachiasmatic nuclei were found to alter serum levels of prolactin in the same direction, an effect that was counteracted by daily afternoon melatonin administration. Melatonin, but not other pineal indoles, also prevented sulpiride-induced prolactin secretion in pinealectomized or suprachiasmatic nuclei-lesioned and ovariectomized rats, which suggested that the pineal gland can modulate prolactin secretion by acting through a dopamine mechanism independent of hypothalamic suprachiasmatic structures.The authors thank Ms Karen Shashok for revising the English style. This work was supported in part by a grant GG85-0168 from the Comisión Asesora de Investigación Cientifica y Ténica. The NIAMDD, through the National Pituitary Agency, supplied the radioimmunoassay materials for prolactin determinations.     

Sexual maturation in female rats: Hereditary,developmental and environmental aspects

Two physiological components of sexual maturation, vaginal opening and first estrus, apparently evolve similarly in Wistar and Sprague-Dawley rats. However, a bimodal distribution in the frequency of the days of vaginal opening is observed within a given strain, which is less related to heredity than to the timing and type of experiment. In addition, when the modulators of sexual maturation are reviewed, it can be observed that sensitivity to external stimuli can vary even within a strain. For a defined set of breeding conditions, one group of rats can be more susceptible to changes in the lighting regimen and not be affected by controlled stressors, while another group responds more to stress and less to light. The reason for susceptibility to one rather than another environmental factor under similar breeding conditions is not understood. In that context, it is difficult to evaluate the role of heredity when we cannot understand the full impact of the environment, not to mention maternal influence in fetal and early life. Using two lines of psychogenetically selected rats, it was possible to show that they had differences in sexual maturation, which strongly suggested a genetic predisposition. Nevertheless, the question arises as to whether the genetic locus directly affects organs implicated in sexual maturation or whether it acts on some unknown factor which only secondarily modifies sexual maturation. In summary, there is more need to understand the role of the environment, including that of the mother early in fetal and neonatal life. It is suggested that the mechanisms underlying organ growth are set for a given species, while developmental and environmental factors fix the timing of vaginal opening and first ovulation. In the rat, there appear to be two times which are preferred for vaginal opening, given the laboratory conditions that have been used in the last 20 or so years: an early period, at 31–35 days, and a late period, at 36–40 days. An explanation for this dichotomy would be that a combination of parameters (not necessarily always the same) is needed for vaginal opening. These parameters oscillate during sexual maturation with different frequencies, which can achieve resonance to lead to vaginal opening and ovulation only during given periods.     

褪黑素对IP诱导Tau过度磷酸化的保护作用

通过对大鼠海马双侧注射异丙肾上腺素(IP)或同时注射褪黑素(0．1μg,1μg),利用免疫组化、免疫印迹和Morris水迷宫等指标,在整体上观察褪黑素对IP诱导的骨架蛋白Tau过度磷酸化和动物保留记忆损伤的保护作用．结果显示0．1μg和1μg剂量的褪黑素能明显降低IP引起的海马骨架蛋白Tau Ser396／404位点的过度磷酸化;1μg褪黑素可明显改善IP引起的动物保留记忆损伤,提示褪黑素对大鼠学习记忆和海马骨架蛋白Tau有一定的保护作用．     

Nicotinamide-Induced Apoptosis Can Be Enhanced by Melatonin in Mouse Myeloma Cells

Introduction Apoptosis is a genetically controlled cell death process which is indispensable to embryogenesis, organ devel- opment, homeostasis, and pathological processes in the life cycle of living things. Apoptosis is characterized by a series of typic…     

电损毁树松果腺对生殖系统影响的研究

本文观察了在生殖季节末期利非生殖季节未期,损毁松果腺的26只树性腺和附性腺重量及组织学的变化.结果发现损毁树松果腺未见影响动物体重.在生殖季节末期损毁树松果腺,未见抑制性腺和附性腺重量减少,但见其在组织学水平上不衰退;在非生殖季节末期损毁树松果腺,未见性腺和附性腺提前增重,但见其在组织学水平上提前恢复.     

Central neural control of pineal melatonin synthesis in rat

Summary To investigate a possible central neural influence on nocturnal pineal metabolic activity, frontal transsections of the stria medullaris thalami were conducted. Enzymes involved in melatonin synthesis, i.e. N-acetyltransferase and hydroxyindole-O-methyl-transferase, exhibited reduced activities in operated animals when compared to controls. These results indicate a modulatory role of central structures on noctural pineal indole metabolism.This study was supported by the Deutsche Forschungsgemeischaft and the Stifung Volkswagenwerk. The technical assistance provided by M. Henschel, I. v. Graevenitz and G. Schlich is gratefuly acknowledged.