TY - JOUR
T1 - Ibotenate Lesions of the Diagonal Band of Broca Attenuate Baroreceptor Sensitivity of Rat Supraoptic Vasopressin Neurons
AU - Cunningham, Joseph Thomas
AU - Nissen, Ralph
AU - Renaud, Leo P.
PY - 1992/1/1
Y1 - 1992/1/1
N2 - Previous electrophysiological studies in the rat suggest that neurons in the diagonal band of Broca participate in baroreceptor‐induced suppression of the spontaneous activity of vasopressin‐secreting neurons in the hypothalamic supraoptic nucleus. In order to test this hypothesis, extracellular recordings were obtained from phasically‐active vasopressin neurons in the supraoptic nucleus of anesthetized rats injected at least 3 days previously with ibotenic acid (1.25 μg/250 nl) in the diagonal band of Broca, the medial and lateral septum, or the median preoptic nucleus. In normal rats, brief increases in blood pressure produced by injections of metaraminol (10 μg/10 μl iv) that were sufficient to activate peripheral baroreceptors, suppressed the activity of a majority (21 tested, 19 suppressed) of phasically‐active vasopressin‐secreting neurons. In rats with ibotenic acid lesions of the diagonal band of Broca, the number of phasically‐active neurons that were baroreceptor‐sensitive was significantly reduced (21 tested, 8 suppressed) while lesions of the medial and lateral septum (17 tested, 16 suppressed) or the median preoptic nucleus (21 tested, 20 suppressed) had no effect. The results support the hypothesis that diagonal band of Broca neurons participate in a central pathway mediating the inhibitory effects of peripheral baroreceptor stimulation on the activity of vasopressin‐secreting neurons in the rat supraoptic nucleus.
AB - Previous electrophysiological studies in the rat suggest that neurons in the diagonal band of Broca participate in baroreceptor‐induced suppression of the spontaneous activity of vasopressin‐secreting neurons in the hypothalamic supraoptic nucleus. In order to test this hypothesis, extracellular recordings were obtained from phasically‐active vasopressin neurons in the supraoptic nucleus of anesthetized rats injected at least 3 days previously with ibotenic acid (1.25 μg/250 nl) in the diagonal band of Broca, the medial and lateral septum, or the median preoptic nucleus. In normal rats, brief increases in blood pressure produced by injections of metaraminol (10 μg/10 μl iv) that were sufficient to activate peripheral baroreceptors, suppressed the activity of a majority (21 tested, 19 suppressed) of phasically‐active vasopressin‐secreting neurons. In rats with ibotenic acid lesions of the diagonal band of Broca, the number of phasically‐active neurons that were baroreceptor‐sensitive was significantly reduced (21 tested, 8 suppressed) while lesions of the medial and lateral septum (17 tested, 16 suppressed) or the median preoptic nucleus (21 tested, 20 suppressed) had no effect. The results support the hypothesis that diagonal band of Broca neurons participate in a central pathway mediating the inhibitory effects of peripheral baroreceptor stimulation on the activity of vasopressin‐secreting neurons in the rat supraoptic nucleus.
KW - baroreceptors
KW - body fluid balance
KW - neurosecretion
KW - vasopressin
UR - http://www.scopus.com/inward/record.url?scp=0026751103&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2826.1992.tb00172.x
DO - 10.1111/j.1365-2826.1992.tb00172.x
M3 - Article
C2 - 21554610
AN - SCOPUS:0026751103
SN - 0953-8194
VL - 4
SP - 303
EP - 309
JO - Journal of Neuroendocrinology
JF - Journal of Neuroendocrinology
IS - 3
ER -