Neurohumoral activation in heart failure: role of paraventricular nucleus.

1. A number of neurohumoral processes are activated in heart failure (HF), including an increase in the plasma concentration of noradrenaline. 2. Few studies have been performed to examine the role of the central nervous system (CNS) in the activation of sympathetic outflow during HF. In the present paper we review the limited studies performed to examine the role of the CNS in the activation of sympathetic outflow, with particular emphasis on our recent study that examined the activity of discrete regions of the brain as assessed by histological localization and photodensitometric quantification of the metabolic enzyme hexokinase during HF. 3. There were significant increases in hexokinase activity in the parvocellular (pPVN) and magnocellular (mPVN) divisions of the paraventricular nucleus of the hypothalamus and in the locus coeruleus (LC) in rats with HF. No changes in hexokinase activity were observed in the median preoptic area, supraoptic nucleus (SON) or posterior hypothalamus. 4. We conclude that HF is associated with changes in specific areas in the brain and that alterations in the activation of neurons in the pPVN, mPVN and LC are likely to be related to alterations in vasopressin production, blood volume regulation and sympathoexcitation observed in the HF state.