Jérôme Roussel

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The effects of gamma-aminobutyric acid (GABA) on the spontaneous and TRH-induced TSH release were investigated in vitro on perifused rat pituitaries. The dynamic pattern of TSH release was measured in response to a 6-min pulse of TRH (10 nM) with or without GABA addition. GABA had no effect on spontaneous TSH release but exhibited a dual effect on(More)
Rat thyrotropin-releasing hormone (TRH) prohormone contains five copies of the TRH progenitor sequence Gln-His-Pro-Gly linked together by connecting sequences whose biological activity is unknown. Both the predicted connecting peptide prepro-TRH-(160-169) (Ps4) and TRH are predominant storage forms of TRH precursor-related peptides in the hypothalamus. To(More)
One week after stereotaxical implantation of a push-pull cannula into the median eminence (ME), rats were stressed by immobilization for 2 h daily for 7 days. Thereafter, ME was perfused for 1 h in basal, stress and recovery conditions, respectively, and somatostatin (SRIH) was measured in perfusate fractions. Pituitaries were in vitro perifused to assess(More)
This work was undertaken to investigate whether the inhibitory tone exerted by GABA on somatostatin (SRIH) release operates in the control of thyrotropin (TSH) secretion in both basal and cold-stimulated conditions. In a first group of animals (G1) undergoing both carotid and third ventricle push-pull cannulation, i.vt. injection of picrotoxin (10(-5) M)(More)
The effect of morphine perfusion into the median eminence on cold-induced TRH secretion was studied in unanesthetized rats by push-pull cannulation. Perfusion with 10(-6)M morphine blocked the cold-induced TRH peak occurring about 40 min after the transfer of rats from 24 degrees C to 4 degrees C. This inhibition by morphine was blunted by concomitant(More)
TRH and somatostatin (SRIH) are well known to stimulate and to inhibit TSH secretion respectively. However, the mechanisms underlying the effect of SRIH on thyrotrophs are still not understood. We have previously shown in vitro that the TSH response to TRH is potentiated in a Ca(2+)-dependent fashion through the activation of dihydropyridine (DHP)-sensitive(More)
The aim of the present study was to determine the functional relationship between blockade of potassium or calcium channel activity and the initial burst of TSH secretion in response to TRH. Perifused rat pituitary fragments were stimulated by a 6-min pulse of physiological concentration of TRH (10 nM) in the presence or absence of pharmacological blockers(More)
The stimulation of TSH secretion by TRH involves the phosphatidylinositol second messenger pathway via activation of phospholipase C. This effect is mediated by a GTP-binding protein and leads to a mobilization of intracellular Ca2+ stores and an activation of protein kinase C. However, TRH stimulation also results in an influx of extracellular Ca2+. Since(More)
The imidazole derivative KK-42 was applied in various experimental conditions to larvae and adult females of Locusta migratoria. The effect of this compound was monitored on the development of larvae, on oocyte growth in adult females and on the development of eggs laid by these females. KK-42 had only minor effects on postembryonic development;(More)