title: Thyrotropin-releasing hormone in rat brain: nyctohemeral variations.
abstract: The concentration of thyrotropin-releasing hormone (TRH) was measured by specific radioimmunoassay in three different brain regions of rats sacrificed every 4 h over a 24 h period. TRH concentration reached a zenith at 1200 h both in the hypothalamus and  the amygdala but did not vary in the forebrain. These results indicate that a nyctohemaral variation of TRH levels exists in hypothalamic and extrahypothalamic brain areas.
mesh_terms: D000679:Amygdala / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002940:Circadian Rhythm; D004027:Diencephalon / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D051381:Rats; D013687:Telencephalon / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
chemical_list: D013973:Thyrotropin-Releasing Hormone