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11.
George B. Stefano Erica Braham Patrick Finn Edward Aiello Michael K. Leung 《Cellular and molecular neurobiology》1987,7(2):209-219
1. This report further demonstrates that etorphine influences presynaptic dopamine release, which in turn centrally modulates peripheral cilioinhibition. 2. In older animals cilioinhibition has become enhanced due to a lack of responsiveness to endogenous opioids which results in greater dopamine release, causing a higher level of cilioinhibition as demonstrated by challenging the visceral ganglia with etorphine or destroying the dopaminergic component with 6-hydroxydopamine. 3. Only the central cilioinhibitory, not the peripheral inhibitory response, mechanism appears to be altered in older animals. Thus, the alteration appears in the central integrative mechanisms involved with regulating ciliary activity. 4. The KCl-stimulated release of dopamine is unaltered in both young and old organisms, whereas the opiate inhibition of the KCl-stimulated release of dopamine is reduced in older organisms. Thus, the aging-associated alteration is associated with a specific process. 5. The reduction of opioid influence and the resulting enhanced cilioinhibitory activity may make the organisms more susceptible to environmental stress. 相似文献
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Stimulation of progesterone and prostaglandin E2 production by lipoxygenase metabolites of arachidonic acid 总被引:1,自引:0,他引:1
The role of several lipoxygenase metabolites of arachidonic acid in the action of luteinizing hormone-releasing hormone (LHRH) on ovarian hormone production was investigated. Like LHRH, treatment of rat granulosa cells with 5-HETE, 5-HPETE, 12-HETE, 15-HETE or 15-HPETE stimulated progesterone (P) and prostaglandin E2 (PGE2) production. 12-HEPE was most potent and stimulated P and PGE2 equally well. By contrast, 5-HETE stimulated P better than PGE2, while 15-HETE was a potent stimulator of PGE2 but not of P. Stimulation of P and PGE2 by LHRH or 12-O-tetradecanoylphorbol 13-acetate (TPA) was further augmented by several HETEs and HPETEs. Like protein kinase C, arachidonic acid metabolites appear to mediate the multiple actions of LHRH in the ovary. 相似文献
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Biochemical and ultrastructural characterization of the 1,4-dihydropyridine receptor from rabbit skeletal muscle. Evidence for a 52,000 Da subunit 总被引:10,自引:0,他引:10
A T Leung T Imagawa B Block C Franzini-Armstrong K P Campbell 《The Journal of biological chemistry》1988,263(2):994-1001
The 1,4-dihydropyridine receptor purified from rabbit skeletal muscle contains four polypeptide components of 175,000 Da (nonreduced)/150,000 Da (reduced), 170,000, 52,000, and 32,000 Da (Leung, A. T., Imagawa, T., and Campbell, K. P. (1987) J. Biol. Chem. 262, 7943-7946). A monoclonal antibody specific to the 52,000-Da polypeptide component of the dihydropyridine receptor has been produced and used in immunoprecipitation and immunoblotting experiments to demonstrate that the 52,000-Da polypeptide is an integral subunit of the purified dihydropyridine receptor. Peptide mapping experiments with 32P-labeled dihydropyridine receptor have also demonstrated that the 52,000-Da polypeptide is distinct from and not a proteolytic fragment of the 170,000-Da subunit. Densitometric scanning of Coomassie Blue-stained sodium dodecyl sulfate-polyacrylamide gels of the purified dihydropyridine receptor has demonstrated that the 52,000-Da polypeptide exists in a 1:1 stoichiometric ratio with the 170,000-, 175,000/150,000-, and 32,000-Da subunits of the dihydropyridine receptor. Electron microscopy of the freeze-dried, rotary-shadowed dihydropyridine receptor has shown that the preparation contains a homogeneous population of 16 x 22-nm ovoidal particles large enough to contain all four polypeptides of the dihydropyridine receptor. The particles have two distinct components of similar size which may represent the location in the molecule of the two larger subunits. 相似文献
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K Leung K E Kim R A Maurer T D Landefeld 《Molecular endocrinology (Baltimore, Md.)》1988,2(3):272-276
Cyclic changes in the production of the pituitary gonadotrophic hormones, LH and FSH are essential events in the maintenance of the reproductive system of female mammals. While studies have examined changes in the secretion of LH and FSH during the estrous cycle and demonstrated the importance of these hormones in regulation of ovarian development and gametogenesis, considerably less is known concerning the regulation of the biosynthesis of these hormones. Although initial studies have examined changes in LH subunit mRNA concentrations during the rat and ovine estrous cycles, no information concerning the physiological regulation of FSH beta mRNA concentrations has been available. In the present study we have examined the relationship between pituitary concentrations of LH and FSH subunit mRNAs and the serum concentrations of these gonadotropins. The results demonstrate a very different pattern of change for FSH beta subunit mRNA than that observed for alpha and LH beta subunit mRNAs. In fact, FSH beta mRNA concentration decline substantially during the preovulatory period, reaching minimal values at a time when alpha and LH beta mRNA levels are near maximal. Furthermore, this decline in FSH beta mRNA amounts occurs when serum FSH concentrations are maximal. Thus, FSH beta mRNA concentrations follow a very different pattern than that of serum FSH. In contrast, LH beta mRNA and serum LH concentrations tend to increase at the same time. These findings provide evidence that concentrations of LH beta and FSH beta mRNAs are likely regulated by different mechanisms. 相似文献
20.
HSPA6 is a member of the human heat-shock protein gene family, encoding a basic 70-kDa protein, with unique induction characteristics (Leung et al., 1990, Biochem. J. 267: 125-132). Hybridization analyses with a somatic cell hybrid DNA panel localized the gene to chromosome 1q. The highly related HSPA7 DNA sequence (Voellmy et al., 1985, Proc. Natl. Acad. Sci. USA 82: 4949-4953) colocalized. Both HSPA6 and HSPA7 represent functional genes, as determined by analyses of mRNA from heat-shocked human cells using specific oligonucleotides, although their pattern of expression differed. Neither mRNA was detected in the absence of heat stress. A BamHI polymorphism in the HSPA7 gene was present in a predominantly Asian population. 相似文献