Delay of constant light-induced persistent vaginal estrus by 24-hour time cues in rats

The normal ovarian cycle of female rats is typically replaced by persistent estrus when these animals are housed under constant light. Evidence presented here shows that the maintenance of periodicity in the environment can at least delay (if not prevent) the photic induction of persistent vaginal estrus. Female rats in constant light were exposed to vaginal smearing at random times or at the same time every day. In another experiment, female rats were exposed to either constant bright light, constant dim light, or a 24-hour photic cycle of bright and dim light. The onset of persistent vaginal estrus was delayed in rats exposed to 24-hour time cues even though the light intensities were the same as or greater than those for the aperiodic control groups. The results suggest that the absence of 24-hour time cues in constant light contributes to the induction of persistent estrus.     

光照控制对蒙古羊发情排卵及相关生殖激素分泌的影响

通过模拟绵羊繁殖季节前后的光照条件,研究光照控制对蒙古绵羊血液褪黑激素(MLT)、促卵泡素(FSH)、促黄体素(LH)浓度分泌的影响,探讨光照条件在控制绵羊繁殖季节中的作用.结果表明:光照控制可诱导蒙古羊在非繁殖季节发情并排卵,对蒙古羊血液MLT分泌影响显著,而对血液FSH和LH分泌没有显著影响.     

Melatonin induction of gonadal quiescence in pinealectomized Syrian hamsters

Pinealectomized Syrian hamsters were injected thrice daily with 25 micrograms of melatonin per injection. The injections were administered at 3-hour intervals either during the day or during the night of a photoperiodic cycle of 14 hours of light and 10 hours of darkness. After 6 weeks of treatment with melatonin during the night, both pinealectomized and intact hamsters had reduced testis weight, and pinealectomized hamsters showed decreased levels of serum gonadotropins. Injection of melatonin during the day for 7 weeks either once (75 micrograms) a day or thrice (25 micrograms per injection) daily caused a reduction in testis weight in pinealectomized hamsters. Both pinealectomized and intact females injected with melatonin thrice daily during the day became anovulatory by week 7 of treatment. These results are similar to those observed when hamsters are exposed to a short photoperiod, suggesting that melatonin may be acting as a hormone in mediating the effects of photoperiod on the reproductive system of the Syrian hamster.     

Ethanol preference in the rat as a function of photoperiod

Ethanol-drinking was induced in laboratory rats that were maintained in total darkness. The established preference for ethanol was not reversed under conditions of constant illumination although a decrease in ethanol intake occurred. Administration of melatonin to rats maintained under "normal" photoperiods (9 hours of darkness during a 24-hour day) also induced ethanol-drinking.     

神经肽Y在动情周期大鼠子宫中的分布

【目的】研究神经肽Y(Neuropeptide Y,NPY)免疫反应阳性物质在大鼠动情周期子宫中的分布情况及其变化规律。【方法】采用阴道涂片法鉴定发情周期,选取情期正常的20只雌性大鼠,均分为动情前期、动情期、动情后期和动情间期4组,处死各组大鼠,取子宫制作石蜡切片,经免疫组织化学SP法染色后,观察NPY在大鼠动情周期子宫中的分布及变化规律。【结果】在内膜层,大多数NPY免疫阳性产物位于细胞中,小部分位于点状和细丝状纤维中。在肌层,NPY免疫阳性产物主要位于NPY纤维中。NPY免疫阳性产物相对表达量的t检验结果表明,子宫内膜NPY在动情期和动情间期的表达较动情前期显著减少(P0.05),较动情后期极显著减少(P0.01);子宫肌层NPY在动情后期的表达较动情期显著回升(P0.05),在动情间期的表达较动情后期极显著减少(P0.01)。【结论】NPY在不同生理时期大鼠子宫中的表达分布存在一定规律性,可能与其生理调节功能有关。     

利用氯前列烯醇诱导奶牛同期发情及定时输精效果分析

[目的]建立一套适合奶牛同情发情及定时输精配种的实用技术,以达到缩短产犊间隔,提高受胎率和牛群的繁殖力。[方法]采用不同给药方式对奶牛进行同期发情处理,并比较研究了定时输精技术对受胎率的影响。[结果]①采用注射2次氯前列烯醇的试验Ⅱ组、试验Ⅴ组的同期发情率极显著高于采用注射1次氯前列烯醇的试验Ⅰ(P<0.01)、Ⅳ组(P<0.01);②采用子宫颈内注入氯前列烯醇的效果较好,试验Ⅵ组(子宫颈内注入2次)的同期发情率和受胎率均高于试验Ⅱ组(肌肉注射2次)(P>0.05),试验Ⅳ组(子宫颈内注入1次)的同期发情率和受胎率也高于试验Ⅰ组(肌肉注射1次)(P>0.05);③采用定时输精方法的试验Ⅲ组、试验Ⅵ组的受胎率分别显著高于试验Ⅱ(P<0.05)、Ⅴ组的受胎率(P<0.05),试验Ⅲ和Ⅵ组的受胎率差异不显著(P>0.05),试验Ⅱ和Ⅴ组的受胎率差异不显著(P>0.05)。[结论]定时输精技术不仅可以省去观察发情,还可以减少因发情鉴定不及时和隐性发情造成的漏配,具有很高的推广应用价值。     

Melatonin suppresses nighttime memory formation in zebrafish

Memory processes are modulated by the biological clock, although the mechanisms are unknown. Here, we report that in the diurnal zebrafish both learning and memory formation of an operant conditioning paradigm occur better during the day than during the night. Melatonin treatment during the day mimics the nighttime suppression of memory formation. Training in constant light improves nighttime memory formation while reducing endogenous melatonin concentrations. Treatment with melatonin receptor antagonists at night dramatically improves memory. Pinealectomy also significantly improves nighttime memory formation. We adduce that melatonin is both sufficient and necessary for poor memory formation during the night.     

褪黑素调控绵羊季节性发情的研究进展

褪黑素是松果腺细胞合成的吲哚胺类激素中生物活性最高的1种神经激素,该激素调节着体内的多种生理活动。对褪黑素的合成、代谢、作用机制以及对绵羊的季节性发情的影响进行了阐述。     

不同处理方法对新疆褐牛同期发情效果的影响

为新疆褐牛胚胎移植和人工授精选择高效的同期发情方法。经直肠检查,具有功能性黄体的新疆褐牛母牛149头,采用CIDR+FSH+PG、孕酮海绵栓+PMSG+PG、1次肌肉注射PG、2次肌肉注射PG、GnRH+PG方法进行同期发情处理,比较不同处理方法同期发情的效果。结果表明:1次肌肉注射PG与CIDR+FSH+PG、孕酮海绵栓+PMSG+PG、2次肌肉注射PG、GnRH+PG方法的同期发情率分别为48.28%与80.65%、75.00%、75.00%、72.41%,差异显著(p0.01)。可见处理方法以2次肌肉注射PG法为好,同期发情率高,简单易操作且成本低。     

补饲对喀斯特地区黄牛同期发情效果的影响

将地方黄牛分为补饲混合精料组、农户自由补饲组和不补饲组进行饲养,3个月后用氯前列烯醇分别按1次和2次注射氯前列烯醇的方法进行同期发情处理.结果表明:补饲混合精料组的发情率、受胎率及同期化程度都显著高于其他两组(p＜0.01),而不补饲组最差;1次和2次注射比较,在补饲的两组中,2次用药的发情率、受胎率及同期化程度都显著高于1次用药组(p＜0.01),而在不补饲组中,虽然2次用药高于1次,但差异不显著(p＞0.05).     

饲喂外源性褪黑素对蛋鸭产蛋性能及生殖激素的影响

为研究通过饲喂方式给予外源性褪黑素对蛋鸭产蛋性能的影响,选取３４只体况及产蛋性能一致的产蛋期山麻鸭,随机分为两组,试验组给予褪黑素每只每天３ｍｇ,对照组不添加;两组均维持２４ｈ的光照,试验期为７周,期间统计蛋鸭采食量、产蛋量及检测相关生殖血清激素水平．结果表明,２４ｈ光照条件下,给予蛋鸭褪黑素在一定程度上降低蛋鸭产蛋性能,同时使蛋鸭血液褪黑素水平上升,雌二醇、促黄体素、孕酮水平下降,但差异均不显著（Ｐ＞０.０５）,表明通过饲喂外源性褪黑素的方式对蛋鸭生殖激素水平影响不大．．     

产后乏情奶牛的诱导发情研究

 本研究用奶牛初乳、新斯的明、孕激素和孕马血清促性腺激素(PMSG)处理产后乏情奶牛,测定处理后24头奶牛乳汁中孕酮(P₄)和17β-雌二醇(17β-E₂)水平变化。结果表明:初乳对产后乏情奶牛的诱导发情作用,可能与处理后乳汁17β-E₂/P₄增加有关;注射初乳时,配合用新斯的明能提高发情率;产后乏情奶牛,用初乳十新斯的明+LRH-A₂方法处理,可有效地诱导发情,且受胎率较高。     

DDT administered to neonatal rats induces persistent estrus syndrome

The o,p'-isomer of the insecticide DDT when injected into neonatal female rats significantly advanced puberty, induced persistent vaginal estrus after a period of normal estrous cycles, and caused the ovaries to develop follicular cysts and a reduced number of corpora lutea. The uterotropic response to administered estradiol was reduced, and the female pattern of mating behavior was slightly disturbed. Residues of DDT in ovarian, brain, and adipose tissues of the adult animals were the same in both treated and control groups.     

外源褪黑素对低温弱光胁迫下茄子幼苗生理特性的影响

以‘春晨长红茄’为材料,采用不同浓度(50、100、150、200、250μmol/L)褪黑素(MT)喷施茄子幼苗叶片,以喷施清水为对照(置于自然光温下为CK,低温弱光下为CK1),研究MT对低温弱光胁迫下茄子幼苗生理特性的影响。结果表明:浓度低于200μmol/L的MT能保持低温弱光胁迫下茄子幼苗叶片中叶绿素和类胡萝卜素含量,当MT浓度为150μmol/L,茄子幼苗叶片叶绿素总量和类胡萝卜素含量分别比CK1高40.23%和75.00%;喷施MT,有助于提高PSII活性,增大光能捕获和转化效率;喷施MT能提高茄子幼苗叶片POD、SOD、CAT活性,降低MDA含量,促进脯氨酸和可溶性糖的积累,当MT浓度为150μmol/L时,与CK1相比,茄子幼苗叶片POD活性提高了108.66%,可溶性糖含量提高了50.61%。综合本研究结果,喷施MT能提高茄子幼苗叶片对低温弱光的抵抗力,且浓度为150μmol/L时效果较好。     

运用计步器鉴定泌乳盛期荷斯坦奶牛的发情效果研究

[目的]探讨运用计步器对泌乳高峰期荷斯坦奶牛发情的鉴定效果。[方法]利用人工观察鉴定和计步器监测对处于泌乳盛期荷斯坦奶牛进行发情鉴定。[结果]与人工观察鉴定相比,运用计步器监测泌乳盛期奶牛发情的检出率提高了24.01%,不但减少人工成本,而且提高了准确率。[结论]该研究可为奶牛发情鉴定提供可靠依据。     

MELATONIN SYNTHESIS IN THE PINEAL GLAND: CONTROL BY LIGHT

In rats placed in continuous darkness for 6 days, there is a striking increase in the activity of melatonin-synthesizing-enzyme (hydroxyindole-0-methyl transferase) in the pineal gland, but no change in the activity of monoamine oxidase. Since melatonin appears to have a hormonal role in mammals, and its synthesis is confined to the pineal gland, the inhibition of hydroxyindole-O-methyl transferase by light may constitute a mechanism of neuroendocrine regulation.     

Antidepressant and circadian phase-shifting effects of light

Bright light can suppress nighttime melatonin production in humans, but ordinary indoor light does not have this effect. This finding suggested that bright light may have other chronobiologic effects in humans as well. Eight patients who regularly became depressed in the winter (as day length shortens) significantly improved after 1 week of exposure to bright light in the morning (but not after 1 week of bright light in the evening). The antidepressant response to morning light was accompanied by an advance (shift to an earlier time) in the onset of nighttime melatonin production. These results suggest that timing may be critical for the antidepressant effects of bright light.     

高温强光下外源褪黑素对栝楼雌花生理生化特性的影响

为探讨高温强光下外源物质对栝楼雌花生理生化变化的影响,以2年生皖蒌9号为试验材料,研究叶面喷施200 μmol·L^-1褪黑素对高温强光下栝楼雌花的抗氧化酶活性、渗透调节物质、H₂O₂、相对电导率、花粉萌发率、坐果率和单果鲜质量的影响。结果表明,在高温强光下,外源物质褪黑素不仅能显著提高栝楼雌花SOD、POD、CAT和APX等抗氧化酶的活性,有效清除体内H₂O₂(与对照相比降低了34.5%),还能促进渗透调节物质合成和积累,与对照相比,外源褪黑素处理的雌花可溶性糖和脯氨酸含量分别增加了25.8%和45.5%。高温强光条件下,外源物质褪黑素还可有效提高栝楼花粉萌发率,促进栝楼坐果和果实膨大,栝楼坐果率提高了9.1百分点。综上,在高温强光下外源褪黑素能通过提高栝楼雌花抗氧化酶活性和渗透调节能力等,缓解高温危害,提高其坐果率。     

二仙汤抗化疗性卵巢早衰氧化应激的效应观察

目的 观察二仙汤对卵巢早衰（premature ovarian failure,POF）大鼠的抗氧化应激效应。方法 雌性SD大鼠40只,监测一周动情周期,筛选有正常动情周期的大鼠入组,随机分为4组：正常组、模型组、阳性药组和二仙汤组。除正常组外,其余3组使用顺铂注射液造POF模型,阳性药组和二仙汤组在造模同时进行药物干预,灌胃期间监测动情周期,15 d后麻醉取材,应用放免法检测血清性激素卵泡刺激素（follicle timulating hormone,FSH）、黄体生成素（luteinizing hormone,LH）及雌激素（estrogen,E₂）的水平以及氧化应激相关指标丙二醛（malondialdehyde,MDA）、抗氧化指标超氧化物歧化酶（superoxide dismutase,SOD）和过氧化氢酶（catalase,CAT）的含量,显微镜下观察各组卵巢组织的病理改变。结果 与正常组相比较,模型组大鼠动情周期及动情间期明显延长（P<0.01）,血清FSH、LH、MDA含量显著升高（P<0.01）,E₂、SOD及CAT水平显著降低（P<0.01）,卵巢组织中闭锁卵泡增多,窦卵泡数减少。与模型组相比,阳性药组与二仙汤组动情周期缩短（P<0.05或P<0.01）,血清FSH、LH、MDA含量显著降低（P<0.05或P<0.01）,E₂、SOD及CAT的含量显著上升（P<0.05或P<0.01）,闭锁卵泡数量减少,窦卵泡数增多。结论 二仙汤能通过调节POF大鼠的的抗氧化能力来改善卵巢功能,减少氧化应激带来的损伤从而治疗POF。     

Brain serotonin concentration: elevation following intraperitoneal administration of melatonin

The intraperitoneal administration of melatonin to rats caused an increase in brain serotonin concentration, especially in the midbrain. This effect could be demonstrated within 20 minutes of melatonin administration and was not associated with changes in norepinephrine concentration.