title: Microdialysis measurement of monoamine and amino acid release from the medial preoptic region of the sheep in response to heat exposure.
abstract: Concentrations of monoamines and metabolites and amino acids were measured in microdialysis samples taken from the medial preoptic area of 5 conscious sheep before, during and after exposure to an ambient temperature of 45 degrees C. Concentrations of dopamine, noradrenaline and aspartate significantly increased, and those of the serotonin metabolite, 5-hydroxyindole-3-acetic acid (5-HIAA), significantly decreased during heat exposure and although panting was induced, body temperature did not change. Concentrations of noradrenaline and aspartate declined and 5-HIAA increased to preheat exposure levels during the 60 min after the ambient temperature was reduced but levels of dopamine and its metabolite, homovanillic acid, remained elevated. Dopamine, noradrenaline, 5-HIAA and aspartate concentrations were not significantly altered by isolation stress and did not show significant changes in the cortex following heat exposure. These experiments provide further support for the proposed roles of dopamine, noradrenaline, serotonin and aspartate in the neural control of autonomic thermoregulatory responses.
authors.affiliation: AFRC Institute of Animal Physiology and Genetics Research Cambridge Research Station, Babraham, UK.
authors.forename: K M
authors.initials: KM
authors.lastname: Kendrick
authors.forename: C
authors.initials: C
authors.lastname: De la Riva
authors.forename: M
authors.initials: M
authors.lastname: Hinton
authors.forename: B A
authors.initials: BA
authors.lastname: Baldwin
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D015306:Biogenic Monoamines / Q000378:metabolism*; D001833:Body Temperature Regulation; D006358:Hot Temperature; D008297:Male; D011301:Preoptic Area / Q000378:metabolism* / Q000503:physiopathology; D012756:Sheep
chemical_list: D000596:Amino Acids; D015306:Biogenic Monoamines