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V Rausell

Publications and source records attributed to V Rausell.

4 recordsLinked to original sources
PubMed1999

Identification of the TRH-like peptides pGlu-Glu-Pro amide and pGlu-Phe-Pro amide in rat thyroid: regulation by thyroid status.

Rat thyroid contains thyrotropin-releasing hormone (TRH) and TRH-like peptides which react with TRH antisera. We have identified the TRH-like peptides in the thyroid and examined whether their levels are influenced by thyroid status. The peptides were extracted from the thyroid glands of five hyperthyroid rats and purified by ion-exchange chromatography on SP-Sephadex C25 and reversed-phase high performance liquid chromatography. The principal TRH-immunoreactive component exhibited the same retention on HPLC as synthetic pGlu-Glu-Pro amide and a secondary component corresponded to synthetic pGlu-Phe-Pro amide. In agreement with these assignments the main peptide was shown to be acidic when chromatographed on DEAE-Sephadex A25 and the second peptide neutral. The levels of TRH and TRH-like peptides in the thyroid were investigated in hyper-, hypo- and euthyroid rats. Hyperthyroidism was induced by chronic subcutaneous administration of triiodothyronine (T3) and hypothyroidism was produced by addition of propylthiouracil (PTU) to the drinking water. The amounts of the peptides were determined by radioimmunoassay with a TRH-antiserum, carried out after extraction from the tissues and purification by ion exchange chromatography. The mean concentration of TRH-like peptides in the thyroids of the hyperthyroid rats was 95.5+/-25.5 pmol/g, the mean concentration in the hypothyroid rats was 11.7+/-3.4 pmol/g, and in the euthyroid rats 17.6+/-3.2 pmol/g. The concentrations of TRH were less influenced by thyroid status: the values in hyper-, hypo- and euthyroid rats were 47.5+/-9.4, 42.1+/-6.3, and 17.2+/-1.6 pmol/g respectively. The results show that the levels of the TRH-like peptides in rat thyroid are highly sensitive to thyroid status, suggesting a possible involvement in thyroid regulation.

Animals↗
PubMed1998

The thyrotropin-releasing hormone-like peptides pGlu-Phe-Pro amide and pGlu-Glu-Pro amide increase plasma triiodothyronine levels in the mouse; the activity is sensitive to testosterone.

Three naturally occurring peptides, pGlu-Glu-Pro amide, pGlu-Phe-Pro amide and pGlu-Gln-Pro amide, with similar structures to thyrotropin releasing hormone (TRH) have recently been identified but no studies of their in vivo activities have been reported previously. We describe here the ability of pGlu-Phe-Pro amide and pGlu-Glu-Pro amide to influence thyroid status. Subcutaneous administration of these 'TRH-like' peptides in male and female CDI mice led to increased levels of triiodothyronine (T3) and to a lesser extent tetraiodothyronine (T4) in the circulation. pGlu-Phe-Pro amide was more potent than pGlu-Glu-Pro amide; it exhibited a similar potency to pGlu-His-Pro amide (TRH). pGlu-Phe-Pro amide, pGlu-Glu-Pro amide and TRH produced significantly greater effects in the female than in the male. Castration of male mice led to increased activities, with potencies comparable to those seen in the female; in contrast treatment of female mice with testosterone resulted in reduced activities, similar to those observed in the control male. The effects of potassium deprivation on the activities of the TRH-like peptides were also investigated. This diet, which results in decreased testosterone levels in the male, led to increased activities of the TRH-like peptides and TRH, approaching the potencies observed in the female. The results demonstrate that the TRH-like peptides pGlu-Phe-Pro amide and pGlu-Glu-Pro amide which occur naturally in the thyroid gland exhibit biological activity in influencing thyroid status in vivo. The activities are sensitive to testosterone.

Animals↗