Onset of pro-thyrotropin-releasing hormone gene expression in cultured rat anterior pituitary cells is expedited by dexamethasone

The early onset of proTRH gene expression in anterior pituitary (AP) cells in culture and its regulation by dexamethasone (DEX) were investigated. AP cells derived from 15-day-old rats were cultured for up to 4 days in the presence or absence of 10-7M DEX. TRH peptide levels, which could be detected only after 3 days of culture in control cells, were detectable after 1 day in DEX-treated cells. Levels rose from undetectable (<35 fmol/well/0.2 × 106 cells) to 121 ± 11 fmol/well in control cells and from 59 ± 3 to 2978 ± 88 fmol/well in DEX-treated cells (Day 1 to Day 4; means ± SEM, n = 6). ProTRH mRNA levels as analyzed by in situ hybridization showed an excellent correlation with TRH peptide levels: mRNA was already detectable on Day 1 in DEX-treated cells and on Days 2-3 in control cells. DEX stimulated proTRH mRNA levels as determined by Northern blot analysis within 4 h. The half-life of proTRH mRNA was calculated based on a first-order decay model by measuring mRNA levels after addition of 5 μg/ml actinomycin D with or without DEX. The ti of proTRH mRNA in control cells was 13.1 ± 2.8 h and was not influenced by DEX treatment (12.5 ± 2.8 h). Since DEX stimulated proTRH mRNA levels acutely without any increase in mRNA stability, we propose that DEX expedites proTRH gene expression in our AP cell culture system by acting at the transcriptional level

TRH-TSH test in patients with schistosomiasis chronic forms Prova do TRH-TSH em pacientes portadores de formas crônicas da esquistossomose mansônica

<abstract language="por">Diversas alterações na concentração sérica dos hormônios tiroidianos têm sido descritas em associação a doenças crônicas não-tiroidianas. Com relação às doenças hepáticas crônicas, a síndrome do T3 baixo foi descrita em pacientes cirróticos, enquanto a síndrome do T4 elevado foi encontrada em esquistossomóticos com a forma hepatoesplênica compensada. Com o intuito de verificar se as alterações relatadas na esquistossomose mansônica eram de origem "periférica" ou "central", realizamos a prova do TRH-TSH em 12 pacientes esquistossomóticos "puros" (6 hepatointestinais e 6 hepatoesplênicos compensados) e em 5 indivíduos controle. Os resultados obtidos demonstram que o eixo hipotálamo-hipofisário é normal nas formas crônicas da esquistossomose e que provavelmente as alterações previamente relatadas devem ser '"periféricas" e não " centrais"