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为了评价下丘脑以外脑部促甲状腺素释放激素(TRH)与下丘脑的相应关系,我们研究了大鼠下丘脑和下丘脑以外TRH的成熟情况。7天龄大鼠整个脑部和下丘脑以外脑部TRH的绝对增大均达到了3个月成年水平,然而龄大下丘脑的TRH浓度则在23天龄时才与成年水平一样。加之,7天龄大鼠纹状体、海马、脑桥、延髓和小脑的TRH浓度比成年水平高;斯时中脑和大脑皮质者也与成年水平相类似。这些材料表明了下丘脑和下丘脑以外TRH发育的差异,并暗示下丘脑以外TRH的成熟是独立于下丘脑的。本研究提示,下丘脑以外TRH在早年幼龄中枢神经系统内可能起着神经生理学的作用,此时,下丘脑TRH的内分泌作用还不成熟。促甲状腺素释放激素(TRH),最早是从下丘脑分离出来的,而且它的分布遍及整个脑(Winokur & Utiger等1974,Mori等1982)。TRH除了有内分泌作用外,还具有神经药理学和与行为有关的性质(Wilber等1976年)。现已假定脑肽在神经元细胞体内合成并聚集成颗粒,然后经轴突输送到神经末梢(Mckelvy &Epelbaum 1978)。上述这些研究提出了如下可能性,即起源于下丘脑“促甲状腺素区”的神经分泌细胞体(Greer 1951,Hal’asz等1962,Martin等1972)可能发出的轴突不仅到达正中隆起以调节脑垂体分泌的促甲状腺素(TSH),而且也到达下丘脑以外的若干脑区以主要地发挥神经生理作用。在整个新生时期,下丘脑的TRH已经大量成熟(Fisher等1977),并与TSH分泌的增大相关联(Dussault & Labrie 1975)。可是,关于下丘脑以外TRH之发育变化和它的那些最早起源处,能获得的资料还有限。对机械地切除传入神经束(Brownstein等1975)和电解损伤下丘脑(Jackson & Reichlin 1977)所观测到的TRH在下丘脑内减少、在下丘脑以外不减少的结果,导出了TRH除从下丘脑产生外、下丘脑以外亦可产生这个令人感兴趣的设想。不过,这些手术性的破坏性操作可能在手术处遗留下神经分泌细胞的非生理性退变(Lincoln1978,Metthews等1960,Powell & Erulkar 1962)。为了阐明下丘脑和下丘脑以外TRH在成熟期间彼此间的特殊关系,我们觉得必须查明TRH是否在下丘脑以外发育的同时在下丘脑内相随地发育。本材料表明,大鼠下丘脑以外TRH数量上的成熟是先于下丘脑的TRH。
To evaluate the hypothalamic response of hypothalamus to thyrotropin-releasing hormone (TRH) other than the hypothalamus, we investigated the TRH maturation outside the hypothalamus and hypothalamus of rats. The absolute increase of TRH in brain and hypothalamus outside of 7-day-old rats reached 3 months of adulthood, whereas the age-old hypothalamic TRH concentrations were only as high as adulthood at 23 days of age. In addition, TRH concentrations in striatum, hippocampus, pons, medulla oblongata and cerebellum in 7-day-old rats were higher than those in adults; midsagos and cerebral cortex were also similar to adult levels. These materials show differences in TRH development outside the hypothalamus and hypothalamus and suggest that TRH maturation outside the hypothalamus is independent of the hypothalamus. This study suggests that TRH outside the hypothalamus may play a neurophysiological role in early childhood central nervous system, at this time, the hypothalamic TRH endocrine role is not yet mature. Thyrotropin releasing hormone (TRH) was first isolated from the hypothalamus and distributed throughout the brain (Winokur & Utiger et al. 1974, Mori et al. 1982). In addition to its endocrine role, TRH has neuropharmacology and behavior-related properties (Wilber et al. 1976). It has been hypothesized that brain peptides are synthesized in neuronal cells and aggregated into granules, which are then delivered to nerve endings via axons (Mckelvy & Epelbaum 1978). These studies raise the possibility that axons, which may originate in the neurotrophoblast body of the hypothalamic “thyrotropin domain” (Greer 1951, Hal’asz et al 1962, Martin et al 1972) not only reach the median bulge to regulate Thyrotropin (TSH), secreted by the pituitary gland, also reaches several brain regions outside the hypothalamus to exert mainly neurophysiological effects. TRH has been well-matured in the hypothalamus throughout the neonatal period (Fisher et al. 1977) and is associated with an increase in TSH secretion (Dussault & Labrie 1975). However, there is limited information available on the developmental changes of TRH outside the hypothalamus and its earliest origins. The observed decrease of TRH in the hypothalamus and no decrease in the hypothalamus outside of the afferent nerve bundle (Brownstein et al. 1975) and the electrolytic injury hypothalamus (Jackson & Reichlin 1977) leads to the formation of TRH in addition to the hypothalamus In addition, hypothalamus can produce this interesting idea. However, these surgical destructive procedures may leave non-physiological degeneration of neurosecretory cells at the surgical site (Lincoln 1978, Metthews et al 1960, Powell & Erulkar 1962). To elucidate the specific relationship TRH has with each other during maturation in the hypothalamus and hypothalamus, we feel it necessary to find out whether TRH develops concomitantly in the hypothalamus while developing outside of the hypothalamus. This material shows that the number of TRH outside of the hypothalamus in rats matures prior to TRH in the hypothalamus.