Chronic maintenance of rat sperm reserves into old age by previous sexual contact

Summary Extensive copulatory experiences at a younger age provoked chronic changes in the reproductive physiology of old male rats. Continuous access to females was not necessary, sperm numbers were elevated in the 22-month-old males 7 months after a final sexual interaction.     

Plasma and hepatic antioxidant control and vitamin A nutritional status

Twenty-seven rats were divided into three groups and fed on diets containing 0.3, 6 or 60 RE (retinol equivalent) retinyl palmitate/g food. After 7 weeks, hepatic vitamin A uptake was found to be more efficient in vitamin A-deficient rats than in rats given adequate vitamin A. We showed that during the metabolic adaptation of the animals to the level of vitamin A in the diet, extensive modifications occur in the antioxidant defences of the organism. In parallel with the increase in the level of vitamin A, the decrease in the level of -tocopherol in the plasma can bring about a greater susceptibility of the lipoproteins to oxidative stress. Similarly, the decrease in the hepatic -tocopherol level and in glutathione peroxidase activity leads to the weakening of the liver's antioxidant defences.     

Bombesin promotes pancreatic growth in suckling rats

Summary The pancreatic growth promoting effect of long term administration of bombesin was investigated in suckling rats. The authors showed that bombesin given in 10 g/kg b.wt doses s.c. every 8 h for 10 days from the day of parturition stimulated pancreatic growth: it increased pancreatic weight, protein and DNA content, trypsin and amylase activity and trypsin/DNA ratio. Conclusion: Bombesin is an effective stimulator of pancreatic growth in suckling rats.     

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.     

Genetic and pharmacological models of cholinergic supersensitivity and affective disorders

Summary Increased muscarinic sensitivity has been associated with altered hormonal states (hypothyroidism and hyperadrenocorticism), chronic administration of muscarinic antagonists or antidepressants with muscarinic actions, selective breeding for anticholinesterase sensitivity, and certain inbred strains of rats and mice. Thus, both genetic and environmental factors may influence muscarinic receptor sensitivity. The reasonably detailed studies on the selectively-bred rats have revealed that the Flinders Sensitive Line (FSL) rats weigh less, are less active, are more sensitive to muscarinic agonists and to stressors, and have higher concentrations of hippocampal and striatal muscarinic receptors than normal, or the selectively-bred, Flinders Resistant Line (FRL) rats. Thus, there are a number of parallels between FSL rats and depressed humans. The FSL rats may be the first animal model of depression to mimic the actual trait of depression, and not just the state.     

Effect of continuous illumination on secretion of pregnane compounds by the rat ovary

Summary Differences in the secretion of pregnance compounds from rats with follicular polycystic ovaries under constant light and with normal preovulatory ovaries under light-dark conditions were compared. The injection of LH greatly increased the secretion of progesterone. 5-pregnane-3,20-dione and 3-hydroxy-5-pregnan-20-one, in both types of ovaries, but the response of the two progesterone metabolites in the polycystic ovaries was low, suggesting low 5-reductase activity.Acknowledgments. The authors thank the Endocrinology Study Section, NIADDK, Bethesda, MD, USA. for their gift of LH. This study was supported by Research Grant No. 466 154 from the Ministry of Education, Science, and Culture, Japan.     

基于AVR单片机的简易数码相框设计

数码相框是一种以数码照片的保存、回放和浏览为核心功能的产品,随着数码相机的发展,数码相框也出现在越来越多的家庭中。本文以Atmel公司生产的ATmega32A为控制核心,配合SD卡、外围电路和TFT液晶屏提出了一种数码相框的简易设计方案,实现了从SD卡读取bmp格式图片并在TFT液晶屏上显示的简易功能。它比普通的相框体积小、更灵活、更有动感,是现代家庭的必备装饰品。     

乙酰氨基己酸锌大鼠一般生殖毒性试验

目的:评价乙酰氨基己酸锌的一般生殖毒性。方法:采用Ⅰ段生殖毒性试验。设高剂量3.0mg?kg、中剂量1.5mg?kg、低剂量1.0mg?kg及溶剂(空白)对照组,对SD雌、雄性大鼠进行灌服给药。雄鼠交配前连续给药63天,交配过程中继续给药至剖检(约两周);雌鼠交配前连续给药14天,交配后(以孕0天开始计算)继续给药至妊娠8天,对照组灌服溶剂0.5%甲基纤维素。结果:表明乙酰氨基己酸锌各剂量对大鼠的体重和部分脏器有影响,表现为高剂组对雄性大鼠体重增长有所抑制,但未对交配率、生育率有影响,也未对生殖器脏器重量增加抑制;乙酰氨基己酸锌剂量组对雄大鼠心脏、肝脏增长有所抑制;乙酰氨己酸锌低剂组对雄大鼠肝脏增长有所抑制;但对食量、饮水量、交配率、生育率,孕鼠生育率、黄体数、着床数、活胎、死胎数及胎鼠体重、外观、内脏组织、骨骼等各指标均无影响。结论:受试剂量下,该药对雄鼠具有一般生殖毒作用。     

沙棘油口服液对游泳小鼠肝脏酯酶同工酶电泳谱带影响的实验研究

建立灌服沙棘油口服液小鼠的力竭性游泳训练实验模型,采用聚丙烯酰胺垂直板凝胶电泳的方法分析了不同组别小鼠肝脏酯酶同工酶。结果表明,组间的酶谱差异不大,三组对照组酶带数目为15条,而相应的沙棘油口服液组为16条,酶带强度（IN）和酶带强度变化率（PIC）也出现了适应性增强。