半胱胺对草鱼下丘脑-脑垂体组织共孵育中生长激素分泌的影响

采用静态孵育和放射免疫测定技术，研究了生长抑素抑制剂半胱胺盐酸盐对草鱼脑垂体组织单独孵育或下丘脑脑垂体组织共孵育中生长激素分泌的影响。结果表明：脑垂体组织单独孵育时，半胱胺盐酸盐(0．1、1和10mmol／L)对基础生长激素分泌无影响；而下丘脑脑垂体组织共孵育时，半胱胺盐酸盐(0．1、1和10mmol／L)对基础生长激素分泌有明显影响，且是剂量依存的。神经肽hGHRH、sGnRH—A和LHRH—A对CSH影响的下丘脑脑垂体组织共孵育中生长激素分泌均无协同作用。我们认为，半胱胺盐酸盐可在下丘脑水平调节生长激素释放，半胱胺盐酸盐调节草鱼离体生长激素分泌是由下丘脑途径介导的。

Effect of cysteamine hydrochloride on growth hormone secretion from hypothalamus-pituitary tissue in juvenile grass carp(Ctenopharyngodon idellus)

Effects of cysteamine hydrochloride (CSH), a somatostatin-inhibiting agent, on growth hormone (GH) secretion from pituitary fragments (PF) or hypothalamus-pituitary fragments (HPF) of juvenile grass carp ( Ctenopharyngodon idellus) under static incubation conditions were investigated. Different concentrations of CSH (0.1,1 and 10 mmol/L) had no influence on GH release from PF after 1 h and 6 h incubation, but were effective in stimulating GH release from HPF in a dose-dependent manner after 1 h and 6 h incubation. Prolonged treatment of HPF with CSH decreased the magnitude of enhancement of GH levels. CSH and neuropeptides {I. E. , human GH-releasing hormone (hGHRH, 100 nmol/L), luteinizing hormone-releasing hormone analog LHRH-A, (D-Trp6, Pro9) -LHRH, 100 nmol/L]} , or salmon gonadotropin-releasing hormone analogue sGnRH-A, (D-Ala6, Pro9) -LHRH, 100 nmol/L],alone and in combination stimulated GH release from HPF after 1 h static incubation. There was an additive, but not a synergistic effect of CSH and neuropeptides on GH release. These results demonstrate that CSH significantly stimulates GH secretion from HPF, not PF of grass carp under static incubation conditions, suggesting a hypothalamic pathway mediating the action of CSH.