Preparation of &lt;sup&gt;3&lt;/sup&gt;H-[3-Me-His&lt;sup&gt;2&lt;/sup&gt;]TRH as an Improved Ligand for TRH Receptors

Taylor, Richard; Burt, David R.

doi:10.1159/000123177

Cited by 45 publications

(2 citation statements)

References 21 publications

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“…Homogenates of 2-3 glands were pooled for the binding assay, and an aliquot was frozen at -20 °C forTSH measurement. The remai ning homogenate was centrifuged at 1,100 g for 10 min at 4 °C, and the supernatant was further centrifuged at 30.000 g for 30 min at 4 "C. The pellet containing the crude membrane preparation was resuspended in cold 20 mM sodium phosphate buffer (pH 7.4; 200 pi).The binding assay was performed according to the procedure described by Burt and Snyder [5], except for the use of !H-MeTRH as ligand [TRH(.3-Me-HisJ), 41.3 Ci/mmol; New England Nuclear, Boston, Mass., USA], a TRH analogue with greater binding alTinity than TRH [37,40]. The incubation mixture contained the mem brane preparation (about 40 pg protein) and various concentra tions of 'H-MeTRH (0.6-9 n Af).…”

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Influence of Age on the Control of Thyrotropin Secretion by Thyrotropin-Releasing Hormone in the Male Rat

Donda¹,

Reymond²,

Lemarchand-Béraud³

1989

Neuroendocrinology

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Alterations with age in the control of thyrotropin (TSH) secretion by thyrotropin-releasing hormone (TRH) were evaluated at the hypothalamic and pituitary levels in young (3–5 months) and old (22–24 months) male rats. In the hypothalamus, TRH was quantified in the median eminence and in the mediobasal hypothalamus; in the adenohypophysis the membrane receptors for TRH were evaluated as well as the accumulation of TRH in the gland. As for TSH, its concentration was determined in the anterior pituitary gland and in plasma. In the hypothalamus, the concentration of TRH did not differ between young and old rats in the whole mediobasal hypothalamus, but it was significantly less in the old rats at the level of the median eminence (29.9 ± 2.8 vs. 52.2 ± 4.3 ng/mg protein). In the adenohypophysis, the density of receptors for TRH was greater in the old than in the young rats (23.2 ± 3.2 vs. 13.7 ± 1.1 fmol MeTRH/mg gland)-with no change in the affinity constant - and the amount of TRH detected was larger (10.8 ± 1.8 vs. 2.8 ± 0.6 pg/mg gland), illustrative of an age-related increase in TRH accumulation in the pituitary gland. The latter results are contrasting with the findings of unchanged pituitary and plasma concentrations of TSH as well as unmodified TSH response to TRH in old rats. The present data concerning TRH and the analogy with previous observations regarding dopamine in old rats are indicative of reduced neuronal activities with age at the hypothalamic level associated with impairments in the processing of the hypothalamic hormones at the pituitary level.

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confidence: 99%

Influence of Age on the Control of Thyrotropin Secretion by Thyrotropin-Releasing Hormone in the Male Rat

Donda¹,

Reymond²,

Lemarchand-Béraud³

1989

Neuroendocrinology

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“…x were obtained from male Sprague-Dawley rats. Radioreceptor assa~s were performed using (SH)[3-Me-His2]TRH (NEN) as the radioligand (19). Bnefly, tissue sam.ples were homogenized (Brinkman Polytron) in 25 vol.…”

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Biological activities of thionated thyrotropin-releasing hormone analogs

Łankiewicz

Bowers

Reynolds

et al. 1992

Biochemical and Biophysical Research Communications

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SUMMARY:Analogs of thyrotropin-releasing hormone (Glp-His-Pro--NH2, TRH) have been prepared which contain thioamide moieties in the pyroglutamic acid ring, the carboxyamide proline terminus, andin both positions (dithio). These compounds have been tested für TSH-releasing activities (in vitro and in viuo), and for binding to TRH receptors in rat pituitary and cortex. The monothionated analoge showed no significant differences in TSH-releasing potency from TRH either in vitro or in vivo. However, with two thioamide replacements the potency decreases about 50%. Significantly, in terms of receptor selectivity, thionation has resulted in differentiation between brain receptors (p~tuitary and cortex). The Pro'V[CSNH2) and dithio analogs were more selective (higher affinity to pituitary receptors) than the parent hormone, while the analog containing a thioamide replacement in the pyroglutamyl ring had lower affinity and was not selective. These results suggest that the subtle exchange of sulphur for oxygen can have an important impact on both receptor selectivity and affinity within 8 biologically active peptide. 0 1992 Academic Press, Inc.

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Ethopharmacological studies differentiate the effects of various serotonergic compounds on aggression in rats

Olivier

Tulp

1992

Drug Development Research

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Mos, J., B. Olivier, and M.Th.M. Tulp: Ethopharmacological studies differentiate the effects of various serotonergic compounds on aggression in rats. Drug Dev. Res. 26:343-360. 1992.A series of experiments was performed to investigate the effects on aggression of various drugs affecting serotonergic transmission in rats. Using ethologically derived behavioural categories, the behaviour of treated animals was described. Drug effects were observed in two aggression models: resident-intruder aggression (RI) in male rats, and maternal aggression in lactating females during the postpartum period (MA). The 5-HT,, agonists, buspirone, ipsapirone, and 8-OH-DPAT, decreased aggression in RI and MA but simultaneously led to a marked decrease in social interest and activity, indicative of a nonspecific anti-aggressive profile. Nonselective 5-HT agonists, such as RU 24969, eltoprazine (DU 28853), and TFMPP, reduced aggression quite specifically and did not decrease social interest or exploration, but sometimes even increased these behaviours. In RI and MA, the behavioural effects of these drugs were roughly similar. By contrast, MA was more sensitive to the treatment with the 5-HT reuptake blocker fluvoxamine, which blocked RI aggression only nonspecifically at the highest dose. DOI, a 5-HT2 and 5-HT,c agonist, decreased aggressive behaviour and increased inactivity, without affecting social interest and exploration in RI as well as MA. This was, however, accompanied by "wet dog shaking," characteristic of 5-HT2-receptor stimulation. The nonspecific 5-HT agonist (and 5-HT3 antagonist) quipazine also induced "wet dog shaking" at doses that suppressed aggression,

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Preparation of <sup>3</sup>H-[3-Me-His<sup>2</sup>]TRH as an Improved Ligand for TRH Receptors

Cited by 45 publications

References 21 publications

Influence of Age on the Control of Thyrotropin Secretion by Thyrotropin-Releasing Hormone in the Male Rat

Influence of Age on the Control of Thyrotropin Secretion by Thyrotropin-Releasing Hormone in the Male Rat

Biological activities of thionated thyrotropin-releasing hormone analogs

Ethopharmacological studies differentiate the effects of various serotonergic compounds on aggression in rats

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