Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Experiments were done in cats to determine the anatomical and functional organization of neural circuits in the hypothalamus involved in mediating afferent renal nerve information to the neurohypophysis and to spinal autonomic centers. In the first series of experiments immunohistochemical staining with antibodies directed against arginine vasopressin and oxytocin provided a comprehensive analysis of the topographical distribution and morphological characteristics of vasopressin and oxytocin immunoreactive perikarya in the paraventricular nucleus of the hypothalamus. In the second series of experiments, to determine the location of paraventriculo-neurohypophysial and paraventriculo-spinal projecting neurons injections of retrograde tracers (horseradish peroxidase or True Blue) were made into either the neurohypophysis or the thoracic spinal intermediate gray region.;In the third series of experiments, to investigate some of the electrophysiological properties of paraventriculo-neurohypophysial and paraventriculo-spinal projecting neurons, regions of the paraventricular nucleus shown to contain retrogradely labeled neurons from the neurohypophysis and spinal cord, were systematically explored for extracellularly recorded single units antidromically activated by electrical stimulation of the neurohypophysis or the spinal cord in chloralose anesthetized, paralyzed and artificially ventilated cats. These antidromically identified units were then tested for their orthodromic response to electrical stimulation of afferent renal nerves and the buffer nerves (carotid sinus and aortic depressor nerves).;To determine whether afferent renal nerve input onto magnocellular neurosecretory neurons in the paraventricular nucleus influenced the release of vasopressin, a fourth series of experiments was done on cats with the aortic depressor, carotid sinus, vagus and cervical sympathetic nerves cut bilaterally. Afferent renal nerves were electrically stimulated with a 10 s train of pulses (10-100 Hz, 500 {dollar}\mu{dollar}A, 2-5 ms pulse duration). Stimulation of afferent renal nerves consistently elicited a pressor response that had two components: a primary (1{dollar}\sp\circ{dollar}) component and a secondary (2{dollar}\sp\circ{dollar}) component that outlasted the 10 s stimulation period by 2-3 min.;These experiments provide anatomical and physiological evidence for the existence of neurons in the paraventricular nucleus of the hypothalamus that function as components of long-loop reflex pathways involved in the integration of afferent inputs from the kidneys and peripheral cardiovascular receptors and which function in the control of systemic arterial pressure and vasopressin release. (Abstract shortened with permission of author.)



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