Substance P immunoreactivity released from rat spinal cord after kainic acid excitation of the ventral medulla oblongata: a correlation with increases in blood pressure.
Kainic acid injections into the ventral medulla oblongata of sodium pentobarbital-anesthetized rats caused an almost immediate increase in mean arterial pressure which reached hypertensive levels (greater than 200 mm Hg). Correlated with this rise in blood pressure was a two-fold increase in the amount of SP-like immunoreactivity (SPLI) in spinal cord superfusion samples. Baseline values obtained from a pool of two rats went from approximately 10 pg/10 min to approximately 20 pg/10 min. Rats pretreated with intracerebroventricular injections of the serotonin neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT), were also given kainic acid injections into the ventral medulla. 5,7-DHT did not block pressure response to kainic acid nor the elevation of SPLI in spinal cord superfusates. However, baseline levels of SPLI were decreased by approximately 50% in 5,7-DHT-treated rats. These findings show that activation of the ventral medulla oblongata causes an elevation of SPLI in spinal cord superfusates concomitant with an elevation in mean arterial blood pressure. These responses appear to be independent of serotonergic systems.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001931:Brain Mapping; D004525:Efferent Pathways / Q000502:physiology; D007608:Kainic Acid / Q000494:pharmacology*; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D011759:Pyrrolidines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000502:physiology*; D013373:Substance P / Q000502:physiology*
D011759:Pyrrolidines; D015116:5,7-Dihydroxytryptamine; D013373:Substance P; D007608:Kainic Acid