{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,1]],"date-time":"2025-10-01T16:31:23Z","timestamp":1759336283441},"reference-count":39,"publisher":"American Physiological Society","issue":"4","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Regulatory, Integrative and Comparative Physiology"],"published-print":{"date-parts":[[2004,10]]},"abstract":"<jats:p> The presence of endomorphin-like immunoreactivity has been reported in the nucleus tractus solitarius (NTS). It was hypothesized that endomorphins may play a role in cardiovascular regulation in the medial subnucleus of the NTS (mNTS). Endomorphin-2 (E-2, 0.1\u20134 mmol\/l) was microinjected (100 nl) into the mNTS of urethane-anesthetized, artificially ventilated, adult male Wistar rats. E-2 (0.2 mmol\/l) elicited decreases in mean arterial pressure (40 \u00b1 3.5 mmHg) and heart rate (50 \u00b1 7.0 beats\/min). These responses were blocked by prior microinjections of naloxonazine (1 mmol\/l) into the mNTS. Responses to microinjections of E-2 into the mNTS were abolished by prior combined microinjections of d-2-amino-7-phosphonoheptanoic acid (an NMDA receptor antagonist, 5 mmol\/l) and 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[ f]quinoxaline-7-sulfonamide disodium (a non-NMDA receptor antagonist, 2 mmol\/l) into the mNTS. These results were confirmed by extracellular neuronal recordings. Blockade of GABA receptors in the mNTS by prior combined microinjections of gabazine (a GABA<jats:sub>A<\/jats:sub> receptor antagonist, 2 mmol\/l) and 2-hydroxysaclofen (a GABA<jats:sub>B<\/jats:sub> receptor antagonist, 100 mmol\/l) also blocked the responses to E-2. It was concluded that 1) the depressor and bradycardic responses to microinjections of E-2 into the mNTS are mediated via \u03bc<jats:sub>1<\/jats:sub>-opioid receptors as well as ionotropic glutamate receptors, 2) GABAergic neurons in the mNTS, which may inhibit the release of glutamate from nerve terminals, are inhibited by E-2 via \u03bc<jats:sub>1<\/jats:sub>-opioid receptors, and 3) disinhibition caused by the inhibition of GABAergic neurons by E-2 may result in an increase in the glutamate release from nerve terminals, which, in turn, may elicit depressor and bradycardic responses. <\/jats:p>","DOI":"10.1152\/ajpregu.00642.2003","type":"journal-article","created":{"date-parts":[[2004,9,15]],"date-time":"2004-09-15T21:17:48Z","timestamp":1095283068000},"page":"R715-R728","source":"Crossref","is-referenced-by-count":16,"title":["Depressor and bradycardic responses to microinjections of endomorphin-2 into the NTS are mediated via ionotropic glutamate receptors"],"prefix":"10.1152","volume":"287","author":[{"given":"Ken","family":"Kasamatsu","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Vineet C.","family":"Chitravanshi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hreday N.","family":"Sapru","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"24","reference":[{"key":"R1","unstructured":"Ciriello J, Hochstenbach SL, and Roder S. 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