Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thyrotropin-releasing hormone (TRH) stimulates pituitary thyrotropin synthesis and release and also regulates autonomic nervous system functions by acting as a neuromodulator and neurotransmitter. In experimental animals a stimulation of ventilation by thyrotropin-releasing hormone was shown when applied at central nervous system sites that affect respiratory motor output. It was the goal of our study to investigate the respiratory properties of thyrotropin-releasing hormone on basal and stimulated (i.e. CO2-rebreathing) conditions following systemic thyrotropin-releasing hormone application in healthy humans. Thyrotropin-releasing hormone (200 micrograms, 400 micrograms intravenous) initiated a rapid short lasting rise of minute volume, ventilatory air-flow and alveolar oxygen tension under steady state breathing (P less than 0.001). Breathing frequency was less affected, heart rate rose concomitantly (P less than 0.001). While breathing with increasing concentrations of carbon dioxide, minute volume was higher under thyrotropin-releasing hormone than under placebo alone. Further effects (e.g. nausea, dizziness, palpitations) mostly appeared later than respiratory changes and thus may not be responsible for their initiation. Our findings prove systemic thyrotropin-releasing hormone to be a strong respiratory stimulant in man. Response in respiratory output was also accompanied by central nervous system-effects (e.g. dizziness, restlessness, augmented vigilance). The mode of thyrotropin-releasing hormone effects on respiration after peripheral administration is still speculative. An augmented sympathetic output or a direct receptor mediated action at central nervous system sites may be responsible, while a peripheral effect cannot be excluded.
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PMID:Thyrotropin-releasing hormone has stimulatory effects on ventilation in humans. 190 74

14 normal volunteers, 23 patients with euthyroid goiter, 9 patients with hypothyroidism and 17 patients with hyperthyroidism were injected with 400 micrograms thyroliberin (thyrotropin releasing hormone, TRH). The documented side effects were the same in all the 4 groups studied. Subjective symptoms such as flushing, nausea, urinary urgency, dizziness and headache in decreasing sequence were mentioned by 86% of subjects. Shortly after thyroliberin injection, a mean increase of 26 +/- 13 mm Hg for systolic and 14 +/- 6 mm Hg for diastolic blood pressure as well as an increased heart rate by 7.2 +/- 6.6 min-1 was demonstrated. Plasma catecholamines were lowered in patients with euthyroid goiter and hyperthyroidism and raised in patients with hypothyroidism, compared with the controls. Thyroliberin administration was associated with an activation of the sympathoadrenal system. The increments in plasma epinephrine and norepinephrine concentrations were proportional to initial values, but were insufficient to affect blood pressure. The mean increase of 28% for plasma epinephrine and 21% for norepinephrine were maximal in the second to the forth minute, where subjective symptoms, blood pressure and heart rate were already decreasing. In view of the rapid onset of the subjective symptoms as well as the chronotropic and the pressor response, thyroliberin may partly exert these effects centrally or directly on the vascular system, independently of catecholamines. Since individual systolic blood pressure increased by as much as 64 mm Hg, caution is advised in selecting patients with risk factors for testing.
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PMID:[Adverse reactions and changes in norepinephrine and epinephrine in the plasma after intravenous thyroliberin in persons with normal and abnormal thyroid function]. 311 48