Hiromasa Ikegami

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Although gonadotropin-releasing hormone agonists (GnRHa) have been used in the therapy of the endocrine-dependent cancers, their biological mechanism remained obscure. We have studied the roles of mito-gen-activated protein kinase family in the antiproliferative effect of GnRHa on the Caov-3 human ovarian cancer cell line. Reverse transcription -PCR assays(More)
Cyclo(His-Pro) (CHP) is a cyclic dipeptide that is ubiquitously distributed through the central nervous system, including striatum. Many biologic effects of CHP seem to be mediated through a dopaminergic mechanism. To further examine the mechanism of action of this peptide, we have studied effects of chronic CHP treatment on the properties of nigro-striatal(More)
We investigated the effects of metabolites of arachidonic acid on the release of beta-endorphin-like immunoreactivity (beta-end-IR) from rat anterior pituitary cells. Anterior pituitary cells from female rats cultured with arachidonic acid released beta-end-IR in a dose- and time-dependent manner. To determine which metabolites of arachidonic acid(More)
The development of chronic graft-versus-host disease (GVHD), which is induced by the transfer of DBA/2 spleen cells into (C57BL/6 x DBA/2)F1 (BDF1) mice, is closely related to diminished donor anti-host CTL activity and host B cell hyperactivation. Therefore, an approach which activates donor CD8+ T cells or suppresses donor CD4+ T cell-host B cell(More)
The presence of estrogen-independent progesterone receptors (PgR) was demonstrated in a subline of a human endometrial cancer cell line, Ishikawa cells, although the original Ishikawa cells contained estrogen-inducible PgR. Scatchard plot analysis of cytoplasmic binding data in our subline (Ik W) revealed a high affinity binding site for R5020 (A'j, 1.0 UM)(More)
We have evaluated the effect of chronic nicotine intake on the age-associated loss of nigrostriatal dopaminergic neurons. The striatal density of dopamine (D1 and D2) receptors and DA-uptake sites decreased with age. Concomitant with these changes was a pronounced loss of many behavioral functions associated, at least in part, with dopaminergic(More)
Many biologic effects of TRH seem to be mediated via a dopaminergic mechanism. The present study examined the effects of chronic TRH administration on the properties of nigrostriatal dopaminergic neurons. Ten days, continuous subcutaneous TRH administration via an osmotic minipump led to a significant rise in striatal level of 3,4-dihydroxyphenylacetic(More)
In order to investigate the involvement of prolactin-dopamine and dopamine-gonadotropin interactions in the hypothalamo-pituitary axis of hyperprolactinemia, in vitro studies were performed using primary cultures of dispersed rat hypothalamic heterogeneous cells containing tubero-infundibular dopaminergic neurons or gonadotropin-releasing hormone (GnRH)(More)
Histidyl-proline-diketopiperazine [Cyclo (His-Pro) (CHP)] was discovered to be one of the metabolites of TRH. To understand the specific role of CHP in rat hypothalamic dopamine neurons, we examined the in vivo effects of intraventricular (icv) infusion of CHP on the release and synthesis of PRL in the rat pituitary and the 3,4-dihydroxyphenylacetic acid(More)
We have investigated the intracellular mechanisms underlying thyrotropin-releasing hormone (TRH)-mediated [3H]dopamine ([3H]DA) release from dispersed rat tuberoinfundibular dopaminergic (TIDA) neurons. The specific binding of [3H]Me-TRH to these cells is characterized by a single, high-affinity binding site (Kd = 1.2 nM) with a Bmax value of 178 fmol/mg(More)