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Ibotenate Lesions of the Diagonal Band of Broca Attenuate Baroreceptor Sensitivity of Rat Supraoptic Vasopressin Neurons
Author(s) -
Cunningham J. Thomas,
Nissen Ralph,
Renaud Leo P.
Publication year - 1992
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.1992.tb00172.x
Subject(s) - diagonal band of broca , vasopressin , baroreceptor , supraoptic nucleus , ibotenic acid , medicine , endocrinology , chemistry , hypothalamus , neuroscience , preoptic area , central nervous system , biology , blood pressure , heart rate , cholinergic neuron
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.