Anatomical and functional evidence for a stress-responsive, monoamine-accumulating area in the dorsomedial hypothalamus of adult rat brain.
The dorsomedial hypothalamus (DMH) plays an important role in relaying information to neural pathways mediating neuroendocrine, autonomic, and behavioral responses to stress. Evidence suggests that the DMH is a structurally and functionally diverse integrative structure that contributes to both facilitation and inhibition of the hypothalamo-pituitary-adrenal axis, depending on the nature of the stimulus and the specific neural circuits involved. Previous studies have determined that stress or stress-related stimuli elevate tissue concentrations of serotonin (5-hydroxytryptamine; 5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dopamine, and noradrenaline selectively within the DMH. In order to determine the specific region of the rat DMH involved, we used high-performance liquid chromatography with electrochemical detection to measure tissue concentrations of 5-HT, 5-HIAA, dopamine, and noradrenaline within five different subregions of the DMH in adult female Lewis and Fischer rats immediately or 4 h following a 30-min period of restraint stress. Compared to unrestrained control rats, restrained rats had elevated concentrations of 5-HT, 5-HIAA, dopamine, and noradrenaline immediately after a 30-min period of restraint and had elevated concentrations of 5-HT 4 h following the onset of a 30-min period of restraint stress. These effects were confined to a specific region that included medial portions of the dorsal hypothalamic area and dorsal ependymal, subependymal, and neuronal components of the periventricular nucleus. Furthermore, these effects were observed in Lewis rats, but not Fischer rats, two closely related rat strains with well-documented differences in neurochemical, neuroendocrine, autonomic, and behavioral responses to stress. These data provide support for the existence of a stress-responsive, amine-accumulating area in the DMH that may play an important role in the differential stress responsiveness of Lewis and Fischer rats.
Lowry
Christopher A
CA
University of Bristol, University Research Centre for Neuroendocrinology, Bristol, BS2 8HW, UK. c.a.lowry@bristol.ac.uk
Plant
Andie
A
Shanks
Nola
N
Ingram
Colin D
CD
Lightman
Stafford L
SL
D000367:Age Factors; D000818:Animals; D003345:Corticosterone / Q000097:blood; D004298:Dopamine / Q000378:metabolism; D004302:Dorsomedial Hypothalamic Nucleus / Q000033:anatomy & histology* / Q000378:metabolism*; D005260:Female; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D012701:Serotonin / Q000378:metabolism; D013045:Species Specificity; D013312:Stress, Physiological / Q000503:physiopathology*
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D004298:Dopamine; D003345:Corticosterone; D009638:Norepinephrine