鱼类尾部神经分泌系统研究进展

尾部神经分泌系统是鱼类特有的神经分泌系统,位于脊髓末端,是鱼类适应环境的关键。该系统作为应激系统的一部分,在鱼类生理和行为方式等多方面具有综合调节作用。综述了自19世纪末尾部神经分泌系统被发现以来,尤其是近年来生物学家在该系统形态结构及组成、主要内分泌细胞(Dahlgren细胞)及其分泌物的功能和生理调节、神经支配等方面的研究成果,以及一些环境变化引起的应激反应与尾部神经分泌系统的相关性的研究。为研究该系统相关分泌肽及其功能提供更为广泛的参考,同时为进一步了解相关分泌肽在高等脊椎动物甚至人类中的功能提供借鉴。

Folic acid contributes to peripheral nerve injury repair by promoting Schwann cell proliferation, migration, and secretion of nerve growth factor

After peripheral nerve injury, intraperitoneal injection of folic acid improves axon quantity, increases axon density and improves electromyography results. However, the mechanisms for this remain unclear. This study explored whether folic acid promotes peripheral nerve injury repair by affecting Schwann cell function. Primary Schwann cells were obtained from rats by in vitro separation and culture. Cell proliferation, assayed using the Cell Counting Kit-8 assay, was higher in cells cultured for 72 hours with 100 mg/L folic acid compared with the control group. Cell proliferation was also higher in the 50, 100, 150, and 200 mg/L folic acid groups compared with the control group after culture for 96 hours. Proliferation was markedly higher in the 100 mg/L folic acid group compared with the 50 mg/L folic acid group and the 40 ng/L nerve growth factor group. In Transwell assays, the number of migrated Schwann cells dramatically increased after culture with 100 and 150 mg/L folic acid compared with the control group. In nerve growth factor enzyme-linked immunosorbent assays, treatment of Schwa nn cell cultures with 50, 100, and 150 mg/L folic acid increased levels of nerve growth factor in the culture medium compared with the control group at 3 days. The nerve growth factor concentration of Schwann cell cultures treated with 100 mg/L folic acid group was remarkably higher than that in the 50 and 150 mg/L folic acid groups at 3 days. Nerve growth factor concentration in the 10, 50, and 100 mg/L folic acid groups was higher than that in the control group at 7 days. The nerve growth factor concentration in the 50 mg/L folic acid group was remarkably higher than that in the 10 and 100 mg/L folic acid groups at 7 days. In vivo, 80 μg/kg folic acid was intraperitoneally administrated for 7 consecutive days after sciatic nerve injury. Immunohistochemical staining showed that the number of Schwann cells in the folic acid group was greater than that in the control group. We suggest that folic acid may play a role in improving the repair of peripheral nerve injury by promoting the proliferation and migration of Schwann cells and the secretion of nerve growth factors.

In vitro study of neuroendocrine regulation over the testicular development in mud crabs Scylla serrata

The reproductive endocrine activities of neuroendocrine organs and androgenic glands (AG) in male Scylla serrata were investigated with co-incubation technology. In vitro studies show that: (1) the AG in Stage Ⅲ can significantly accelerate the development of seminiferous tubules and spermic matu- ration; (2) the brain, thoracic ganglia and optic ganglia have no direct influence over the testicular devel- opment; (3) the brain and thoracic ganglia can significantly promote the growth of the AG cells and highly significantly boost the ratio of Type B cells, while the optic ganglia have no such effects. It is the first time for in vitro investigations to confirm that the brain and thoracic ganglia can regulate testicular development through AG in male crustaceans.

INTRAPANCREATIC CHOLECYSTOKININ MEDIATES VAGALLY STIMULATED EXOCRINE SECRETION FROM THE RAT PANCREAS

Although cholecystokinin is localized within neuronal fibres of the pancreas, a physiological role for intrapancreatic cholecystokinin has not been identified. The strategy of this study was to elicit pure vagal stimulation electrically, and to use specific receptor antagonists to identify the mediators of exocrine pancreatic secretion. We conclude that vagal stimulation of the rat pancreas involves ganglionic neurotransmission and release of acetylcholine and cholecystokinin from intrapancreatic, postganglionic fibres. To our knowledge, this is the first study to demonstrate a physiological role for intrapancreatic cholecystokinin.

Functional Role of Neuropeptide Leucokininll in Growth Inhibition of Red Palm Weevil Rhynchophorus ferrugineus

Peptides are known to on act to discourage the growth of insects. In this perspective, authors studied the biological and physiological effects of LeucokininlI on the growth of Red Palm Weevil through adult insect feeding of the sugar cane treated with different concentrations （0.05%, 0. I%, 0.25%, 0.4%） and biological effects on the number of eggs, the percentage of hatching, the length of the generation and the proportion of deformation, Results showed that there is a significant reduction in the number of eggs laid by the insects as the average number of eggs/female 75.7, 63.5, 59.4, 55.1 egg for each of the concentrations, respectively, compared with the average 140.2 egg in the control group, and reduction of percentages of hatching in all treatment as 71.4%, 64.6%, 70% and 71.5% respectively, compared with 79.3% of the control group. The percentage of deformations in egg densities included 44.4%, 15.4%, 22.6%, 27.8% compared to the control group. The results showed that there are a number of large deformations in the resulting larvae for different treatments. The conclusion is drawn that this study using LeucokininlI confirmed inhibition growth and caused an imbalance in the development stages of different insects due to its effect on the hormones that control molting of insects. This conclusion is furthermore apparent in the larval stage, as it appeared that Leucokininll prevents the insect from completing its life cycle. Test results using LeucokininlI are encouraging, and its future potential use in reducing Red Palm Weevil deserves broader studies. If the spread of currently known that this LeucokininlI is without prejudice to the work of the hormonal system.

Lethal neuroendocrine carcinoma in ulcerative colitis

A 48-year old male with longstanding and extensive pancolitis developed a high grade and rapidly lethal malignant lesion in the ascending colon characterized by a neuroendocrine carcinoma.Prior biopsies obtained from multiple sites in the colon during endoscopic surveillance were reported to show only inflammatory changes without dysplasia.Although operator-dependent,repeated endoscopic studies may have limitations during surveillance programs because the biological behavior of some colonic neoplastic lesions may have a rapid and very aggressive clinical course.

Neuroendocrine differentiation in prostate cancer

Hormonal therapy is an important treatment for advanced/metastatic prostate cancer. But it can induce neuroen-docrine(NE) differentiation in prostate cancer cells. These NE cells will secrete manifold neural peptide or hormones which can lead to androgen-independent growth of non-NE tumor cells. When this happens,hormonal therapy becomes useless and indicates bad prognosis. In this paper,the mechanism of neuroendocrine differentiation and its relationship with andro-gen-independent were reviewed.

RAT EXOCRINE PANCREATIC SECRETION BYVAGAL STIMULATION OCCURSVIAMULTIPLEMEDIATORS

The vagus is a mixed nerve containing cholinerrgic and non-cholinergic neurons. Vagal fibers interact with peptidergic neurons of the enteric nervous system which stain immunohistochemically for cholecystokinin, vasoactive intestinal polypeptide, and gastrin releasing peptide. The contribution of these peptidergicneurons in the pancreatic response to vagal stimulation is unknown. We tested the effect of specific inhibitor of these stimulants against vagally mediated exocrine secretion in rats. The response to vagal stimulation was blocked significantly by each of the following:the ganglionic blocker hexamethonium (l00% inhibition); the muscarinic, cholinergic blocker atropine (85% inhibition); the specific cholecystokinin-A receptor blocker (91 % inhibition); and a vasoactive intestinal polypeptide polyclonal antibody (89% inhibition). This observation is consistent with the hypothesis that potentiating interactions among several agonists mediate the vagal response. Our study, however, dose not exclude acetylcholine as the final commommediator.