Effect of thyroid status and paraventricular area lesions on the release of thyrotropin-releasing hormone and catecholamines into hypophysial portal blood. 1988

J M Rondeel, and W J de Greef, and P van der Schoot, and B Karels, and W Klootwijk, and T J Visser
Department of Endocrinology, Growth and Reproduction, Medical Faculty, Erasmus University, Rotterdam, The Netherlands.

TRH is a potent stimulator of pituitary TSH release, but its function in the physiological regulation of thyroid activity is still controversial. The purpose of the present study was to investigate TRH and catecholamine secretion into hypophysial portal blood of hypothyroid and hyperthyroid rats, and in rats bearing paraventricular area lesions. Male rats were made hypothyroid with methimazole (0.05% in drinking water) or hyperthyroid by daily injections with T4 (10 micrograms/100 g BW). Untreated male rats served as euthyroid controls. On day 8 of treatment they were anesthetized to collect peripheral and hypophysial stalk blood. In euthyroid, hypothyroid and hyperthyroid rats plasma T3 was 1.21 +/- 0.04, 0.60 +/- 0.04, and 7.54 +/- 0.33 nmol/liter, plasma T4 50 +/- 3, 16 +/- 2, and 609 +/- 74 nmol/liter, and plasma TSH 1.58 +/- 0.29, 8.79 +/- 1.30, and 0.44 +/- 0.03 ng RP-2/ml, respectively. Compared with controls, hyperthyroidism reduced hypothalamic TRH release (0.8 +/- 0.1 vs. 1.5 +/- 0.2 ng/h) but was without effect on catecholamine release. Hypothyroidism did not alter TRH release, but the release of dopamine increased 2-fold and that of noradrenaline decreased by 20%. Hypothalamic TRH content was not affected by the thyroid status, but dopamine content in the hypothalamus decreased by 25% in hypothyroid rats. Twelve days after placement of bilateral electrolytic lesions in the paraventricular area plasma thyroid hormones and TSH levels were lower than in control rats (T3: 0.82 +/- 0.05 vs. 1.49 +/- 0.07 nmol/liter; T4: 32 +/- 4 vs. 66 +/- 3 nmol/liter; TSH: 1.08 +/- 0.17 vs. 3.31 +/- 0.82 ng/ml). TRH release in stalk blood in rats with lesions was 15% of that of controls, whereas dopamine and adrenaline release had increased by 50% and 40%, respectively. These results suggest that part of the feedback action of thyroid hormones is exerted at the level of the hypothalamus. Furthermore, TRH seems an important drive for normal TSH secretion by the anterior pituitary gland, and thyroid hormones seem to affect the hypothalamic release of catecholamines.

UI MeSH Term Description Entries
D006980 Hyperthyroidism Hypersecretion of THYROID HORMONES from the THYROID GLAND. Elevated levels of thyroid hormones increase BASAL METABOLIC RATE. Hyperthyroid,Primary Hyperthyroidism,Hyperthyroidism, Primary,Hyperthyroids
D007037 Hypothyroidism A syndrome that results from abnormally low secretion of THYROID HORMONES from the THYROID GLAND, leading to a decrease in BASAL METABOLIC RATE. In its most severe form, there is accumulation of MUCOPOLYSACCHARIDES in the SKIN and EDEMA, known as MYXEDEMA. It may be primary or secondary due to other pituitary disease, or hypothalamic dysfunction. Central Hypothyroidism,Primary Hypothyroidism,Secondary Hypothyroidism,TSH Deficiency,Thyroid-Stimulating Hormone Deficiency,Central Hypothyroidisms,Deficiency, TSH,Deficiency, Thyroid-Stimulating Hormone,Hormone Deficiency, Thyroid-Stimulating,Hypothyroidism, Central,Hypothyroidism, Primary,Hypothyroidism, Secondary,Hypothyroidisms,Primary Hypothyroidisms,Secondary Hypothyroidisms,TSH Deficiencies,Thyroid Stimulating Hormone Deficiency,Thyroid-Stimulating Hormone Deficiencies
D008297 Male Males
D009638 Norepinephrine Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic. Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D010286 Paraventricular Hypothalamic Nucleus Nucleus in the anterior part of the HYPOTHALAMUS. Hypothalamic Paraventricular Nucleus,Paraventricular Nucleus,Hypothalamic Nucleus, Paraventricular,Nucleus, Hypothalamic Paraventricular,Nucleus, Paraventricular,Nucleus, Paraventricular Hypothalamic,Paraventricular Nucleus, Hypothalamic
D010902 Pituitary Gland A small, unpaired gland situated in the SELLA TURCICA. It is connected to the HYPOTHALAMUS by a short stalk which is called the INFUNDIBULUM. Hypophysis,Hypothalamus, Infundibular,Infundibular Stalk,Infundibular Stem,Infundibulum (Hypophysis),Infundibulum, Hypophyseal,Pituitary Stalk,Hypophyseal Infundibulum,Hypophyseal Stalk,Hypophysis Cerebri,Infundibulum,Cerebri, Hypophysis,Cerebrus, Hypophysis,Gland, Pituitary,Glands, Pituitary,Hypophyseal Stalks,Hypophyses,Hypophysis Cerebrus,Infundibular Hypothalamus,Infundibular Stalks,Infundibulums,Pituitary Glands,Pituitary Stalks,Stalk, Hypophyseal,Stalk, Infundibular,Stalks, Hypophyseal,Stalks, Infundibular
D011919 Rats, Inbred Strains Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding. August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D012016 Reference Values The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality. Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
D004298 Dopamine One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action. Hydroxytyramine,3,4-Dihydroxyphenethylamine,4-(2-Aminoethyl)-1,2-benzenediol,Dopamine Hydrochloride,Intropin,3,4 Dihydroxyphenethylamine,Hydrochloride, Dopamine
D004837 Epinephrine The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS. Adrenaline,4-(1-Hydroxy-2-(methylamino)ethyl)-1,2-benzenediol,Adrenaline Acid Tartrate,Adrenaline Bitartrate,Adrenaline Hydrochloride,Epifrin,Epinephrine Acetate,Epinephrine Bitartrate,Epinephrine Hydrochloride,Epinephrine Hydrogen Tartrate,Epitrate,Lyophrin,Medihaler-Epi,Acetate, Epinephrine

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