Effects of neonatal antithyroid treatment on brain [3H]‐imipramine binding sites

Vaccari, Andrea

doi:10.1111/j.1476-5381.1985.tb16160.x

Cited by 9 publications

(4 citation statements)

References 19 publications

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“…There was no effect of hyperthyroidism on these uptake sites. In contrast, no change in 3H-IMI binding was seen in rats treated chronically with antithyroid drugs [42], However, in an another study [43], an increase in 3 H-IMI binding was reported following treatment with antithyroid agents.…”

Section: Discussionmentioning

confidence: 80%

Time Course of Altered Thyroid States on 5-HT1A Receptors and 5-HT Uptake Sites in Rat Brain: An Autoradiographic Analysis

Tejani‐Butt¹,

Yang²,

Kaviani³

1993

Neuroendocrinology

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Although a link between the hypothalamic-pituitary-thyroid (HPT) axis and affective disorder has been established, the mechanism underlying this relationship remains unclear. Since the serotonin (5-HT) system appears to be involved in the pathophysiology of mood disorders, the time course of the effects of thyroidectomy (TXT) with or without thyroxine (T₄) replacement on 5-HT1a receptors and 5-HT uptake sites was examined. TXT caused a significant increase in ³H-8-hydroxy-2-(di-n-propylamino)-tetralin (³H-DPAT) binding to 5-HT1a receptors in the cortex and hippocampus at 7 days and this increase was also evident at 35 days following TXT. By contrast, TXT did not have a significant effect on ³H-DPAT binding in the hypothalamus or in the dorsal raphe nucleus. TXT did not affect the binding of ³H-cyanoimipramine (³H-CN-IMI) to 5-HT uptake sites in any of the brain regions analyzed, or at any of the time points studied. Administration of high-dose T₄ for 28 days caused the binding of ³H-DPAT to recover to sham levels in the cortex, to increase in the hippocampus and hypothalamus, and had no effect in the dorsal raphe nucleus. Replacement with high-dose T₄ had no effect on ³H-CN-IMI binding to 5-HT uptake sites when compared to sham-operated animals at all time points examined. These results suggest that a neuromodulatory link may exist between the HPT axis and 5-HT1a receptors in the limbic regions of the rat brain. Depending on the brain region examined, a differential response to circulating levels of thyroid hormone was observed.

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Section: Discussionmentioning

confidence: 80%

Time Course of Altered Thyroid States on 5-HT1A Receptors and 5-HT Uptake Sites in Rat Brain: An Autoradiographic Analysis

Tejani‐Butt¹,

Yang²,

Kaviani³

1993

Neuroendocrinology

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“…We have previously shown (Vaccari, 1985) (Palkovits et al, 1981;Fuxe et al, 1983). Furthermore, when the binding reaction of [3HJ-imipramine was run in the presence of low concentrations of MMI, there was a consistent increase in the number of brain imipramine binding sites compared to controls.…”

Section: Introductionmentioning

confidence: 57%

“…In a companion paper (Vaccari, 1985) we have described the effects of a chronic antithyroid treatment with MMI on brain imipramine binding sites. Since MMI is a thiol compound (1-methyl-2-mercaptoimidazole), and alterations of either disulphide bridges and/or SH groups in the receptor subunit or on associated proteins, may be functionally significant for ligand-receptor interactions (Bennett & Snyder, 1976;Fillion & Fillion, 1980;Suen et al, 1980;Wennogle et al, 1981;Hamon et al, 1983;Peterson & Bartfai, 1983;Woodruff et al, 1984), the in vitro effects of membrane-active reagents on central [3H]-imipramine binding sites and on additional putative receptors have been studied here in detail.…”

Section: Discussionmentioning

confidence: 99%

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Selective effects of thiol reagents on the binding sites for imipramine and neurotransmitter amines in the rat brain

Biassoni

Vaccari

1985

British J Pharmacology

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IThe action of the antithyroid drugs methimazole (MMI) and propylthiouracyl (PTU) on 4 The effects ofNEM on imipramine recognition sites and on the uptake of 5-HT could be prevented by DTT; protection was not obtained in other receptor systems.5 Three groups of receptors have been, thus, postulated, based upon their different sensitivity towards alterations in membrane [disulphide bridges = SHJ equilibrium: Group I, including imipramine recognition sites and the uptake system for 5-HT; Group II, including 5-HT,-receptors; Group III, including 5-HT2-and D2-receptors.

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[3H]Tyramine binding: A comparison with neuronal [3H]-dopamine uptake and [3H]mazindol binding processes

Vaccari

Gessa

1989

Neurochem Res

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[3H]Spiperone [( 3H]SPI) binding sites in rat or bovine striata have been solubilized using CHAPS or digitonin detergents. Solubilized sites retained the binding characteristics of those in native membrane preparations. The same solubilized material, however, did not bind [3H]tyramine [( 3H]PTA), thus indicating that [3H]PTA binding sites and DA receptors are different chemico-physical entities. In membrane preparations or crude synaptosomes obtained from the c.striatum of neonatally-rendered hypothyroid rats, when central DA-pathways are impaired, both [3H]PTA binding and [3H]DA uptake processes were markedly decreased, with no effect on [3H]mazindol [( 3H]MAZ) binding, compared to euthyroids. Reserpine, a well-known inhibitor of DA-uptake into a variety of secretory vesicles, and a potent in vivo and in vitro inhibitor of [3H]PTA binding, did not affect the [3H]MAZ binding process. This further supported the suggestion that while [3H]PTA binding sites are almost totally associated with the vesicular transporter for DA, [3H]MAZ does label a site involved in the DA-translocation across the neuronal membrane. The latter process seems to be rather insensitive to thyroid hypofunction, when however the intracellular storage of DA might be consistently impaired. In conclusion, PTA might be well exploited as a marker of the DA vesicular transporter through its molecular characterization, whenever possible.

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Effects of neonatal antithyroid treatment on brain [³H]‐imipramine binding sites

Cited by 9 publications

References 19 publications

Time Course of Altered Thyroid States on 5-HT<sub>1A</sub> Receptors and 5-HT Uptake Sites in Rat Brain: An Autoradiographic Analysis

Time Course of Altered Thyroid States on 5-HT<sub>1A</sub> Receptors and 5-HT Uptake Sites in Rat Brain: An Autoradiographic Analysis

Selective effects of thiol reagents on the binding sites for imipramine and neurotransmitter amines in the rat brain

[3H]Tyramine binding: A comparison with neuronal [3H]-dopamine uptake and [3H]mazindol binding processes

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