二甲苯胺噻唑对家兔血液、脑脊液、垂体及下丘脑中β－内啡肽浓度的影响

用放射免疫分析法（ＲＩＡ）研究二甲苯胺噻唑（静松灵）对家兔血液、脑脊淮、垂体及下丘脑中β－内啡肽（β－Ｅｐ）浓度的影响。给家兔肌注静松灵（３４ｍｇ／ｋｇ）后，家兔血液及脑脊液中β－Ｅｐ在用药后１．５ｈ增至最高值，即由用药前的７２．０８±４．０５ｐｇ／ｍＬ增至２８９．５４±１０．０４（Ｘ±ＳＥ，ｎ＝５，Ｐ＜０．０１），升高了７５．１１％；脑脊液中β－Ｅｐ在注药后１ｈ增至最高值，即由５３３．４９±１６．５５ｐｇ／ｍＬ增至１９０８．８０±２８．３６ｐｇ／ｍＬ（Ｘ±ＳＥ，ｎ＝５，Ｐ＜０．０１）增高了７２．０８％，经统计分析差异极显著，而对照组，注射前后家兔血液及脑脊液中β－Ｅｐ浓度未见明显变化。给药后家兔垂体及下丘脑中β－Ｅｐ浓度与给药前比较是动态变化规律，垂体中β－Ｅｐ在给药后３０ｍｉｎ降至最低值，即由２４６．６５±４．４２ｐｇ／ｍｇ降至１２０．５０±８．０９ｐｇ／ｍｇ（Ｘ±ＳＥ，ｎ＝３，Ｐ＜０．０１）降低了５１．１５％，以后是回开趋势，给药后３ｈ增至最高值：３３８．６０±１４．７８ｐｇ／ｍｇ，增加了２７．２６％，经统计分析，差异极显著；下丘脑中β－Ｅｐ浓度在给药后３０ｍｉｎ降至最低值，即由３２．１４±１．３０ｐ?     

A drop in ambient temperature results in a transient reduction of interrenal ACTH responsiveness in the gilthead sea bream (Sparus aurata, L.)

This study investigated the effects of a drop in water temperature (18 °C to 9 °C in 24 h) on the pituitary and interrenal hormones of the gilthead sea bream Sparus aurata. The in vitro sensitivity of the interrenal tissue to ACTH, plasma levels of cortisol, ACTH, -MSH, GH, glucose, lactate and ions were determined. In vitro ACTH, stimulated the release of cortisol from isolated interrenal glands from control gilthead sea bream in a concentration dependent fashion. However, the interrenal cells were less sensitive to ACTH as soon as 24 h following the onset of the temperature drop. At this time, plasma cortisol and ACTH levels were raised, and plasma GH concentrations were decreased, whereas no significant changes were found in plasma -MSH. After 96 h plasma ACTH levels had recovered whereas plasma cortisol levels were still higher than controls after 8 days of the beginning of the experiment. Interrenal sensitivity had recovered after 8 days. The results may help to clarify the relationship between the stress response and the aetiology of the winter syndrome in sea bream.     

浅色黄姑鱼脑垂体cDNA文库的构建

以浅色黄姑鱼脑垂体为材料,应用SMART~(TM) cDNA library construction技术,构建以真核表达载体pcD- NA3．1( )为基础的浅色黄姑鱼cDNA文库。利用含Sfi I B酶切位点的oligo(dT)引物合成cDNA第一链,利用含Sfi I A酶切位点的SMART核苷酸作为cDNA第一链在mRNA5′端延伸出去的模板,采用LD PCR引物合成双链cDNA,双链cDNA用Sfi I酶切和过柱分级分离后,与引入Sfi I酶切位点的pcDNA3．1( )-Sfi I载体进行连接,转化大肠杆菌TOP10感受态细胞,构建成脑垂体全长cDNA文库。经过质量鉴定,得到的原始cDNA文库含有约1×10~5个重组子,重组率为90%,插入cDNA片段长度范围约为0．4～3kb。研究为深入开展浅色黄姑鱼的生长发育相关基因的研究奠定了良好的基础。     

The reproductive brain in fish

In fish as in other vertebrates, the brain is actively involved in the control of reproduction, first by participating, under the influence of external factors, in the establishment of an appropriate endocrine status, but also by allowing synchronization of the partners by the time of spawning. It is now well established that the pituitary gonadotropic function is controlled by multiple stimulatory and inhibitory factors, originating mainly from the preoptic region and the mediobasal hypothalamus, both target regions for sexual steroids. Little is known about the mechanisms involved in the mediation of external and internal factors, however there is indication that internal factors, such as androgens and melatonin, known to trigger particular behavioural and endocrine responses, act both at the level of neuroendocrine territories, but also on sensorial systems, which are the actual sites of action for external factors. This paper represents an attempt to summarize and integrate the recent literature devoted to the different aspects of the brain as a major participant in the complex endocrine and behavioural mechanisms of reproduction in fish.     

Development of the hypophysis of the arctic lamprey,Lampetra japonica

The hypophysis of early larval stages, from the moment of hatching on the 18th day after fertilization to the 101st day of larval life, of the arctic lamprey Lampetra japonica was studied with scanning and transmission electron microscopes. A solid cord of cells of the distal part of the nasopharyngeal duct represents the early adenohypophysis. On the 20th day after fertilization, several of the epithelial cells of this structure showed first indications of secretory activity with an extensive Golgi apparatus and small electron-dense secretory granules. On the 26th day, non-secretory, stellate (=supporting) cells and secretary cells can be distinguished. Already on the 39th day, two different parts can be distinguished in the adenohypophysis: the pars distalis with cells containing small dense granules, and the pars intermedia with cells containing larger granules of medium density. The number of granulated cells increases steadily; on the 101st day two pars distalis cell types can be distinguished. The neurohypophysis consists of a thin anterior and a thick posterior part. Already on the 20th day single nerve terminals in the ependymal layer of the diencephalic (=infundibular) floor contain dense elementary granules. The number of granule-containing terminals increases steadily; on the 101st day almost all terminals contain granules. The present observations suggest an early secretory function of the lamprey hypophysis.     

Gonadotropins I and II in juvenile coho salmon

The present study was designed to obtain basic endocrine information on GTH I and GTH II in previtellogenic and prespermatogenic coho salmon (immature). Levels of GTH II in pituitary extracts were 6.5 ± 2.0 and 6.7 ± 2.0 pg/μg pituitary protein in male and female fish, respectively. In contrast, the pituitary content of GTH I was approximately 100-fold higher than GTH II (1.302 ± .22 and 1.173 ± .21 ng/μg pituitary protein in male and female fish, respectively). Plasma levels of GTH II in immature salmon were not detectable by RIA whereas plasma GTH I levels were approximately 0.62 ± 0.12 and 0.78 ± 0.13 ng/ml in male and female fish, respectively. Highly purified coho salmon GTH I and GTH II stimulated testicular testosterone production and ovarian estradiol productionin vitro in a similar manner, though GTH II appeared more potent than GTH I. Therefore, it appears that although the salmon pituitary contains predominantly GTH I prior to puberty, the gonad can respond to both GTH I and GTH II.     

Fundulus heteroclitus Gonadotropin(s) 2. Year-round husbandry of animals with active pituitaries and responsive follicles

Mummichogs (Fundulus heteroclitus) were exposed to various regimens of temperature and photoperiod in order to develop a routine husbandry procedure so as to have throughout the year a population of reproductively healthy fish with a good quantity and quality of prematuration follicles (1.2–1.5 mm) suitable for carrying out homologous bioassays ofF. heteroclitus gonadotropin. During the fall and winter months, wild fish in the field all had regressed ovaries (gonadosomatic index <1). On the other hand, laboratory-maintained fish, with or without cold temperature (15°C) and short photoperiod (10 h light/day) pretreatment, generally had sexually mature ovaries (GSI>10) when maintained on a warm temperature (25°C) and long photoperiod (14 h light) protocol. Ovarian follicles retrieved from laboratory fish were responsive toF. heteroclitus pituitary extract stimulation, and underwent germinal vesicle breakdown normallyin vitro. Hence these ovarian follicles served well as a bioassay forF. heteroclitus gonadotropin even outside of the normal breeding season. The pituitary glands retrieved from laboratory fish in winter also retained high gonadotropic potencies, in terms of maturational and steroidogenic activities. Our results thus demonstrated that active gametogenesis in laboratory-maintained fish can be extended five months beyond the end of the normal breeding season. Apparently,F. heteroclitus in Florida is potentially a continuous breeder when under favorable conditions, but has a reproductive quiescent period imposed upon it by some environmental stressor(s). Although the design of the present experiments did not determine the relative importance of nutritional factors, temperature, and photoperiod on the annual reproductive cycle ofF. heteroclitus, there are indications that diatary factors may play a much more dominant role in the reproductive cycle than previously recognized.