Cortical spreading depression reduces paraventricular activation induced by hippocampal neostigmine injection

ASICs as therapeutic targets for migraine

Migraine is the most common neurological disorder and one of the most common chronic pain conditions. Despite its prevalence, the pathophysiology leading to migraine is poorly understood and the identification of new therapeutic targets has been slow. Several processes are currently thought to contribute to migraine including altered activity in the hypothalamus, cortical-spreading depression (CSD), and afferent sensory input from the cranial meninges. Decreased extracellular pH and subsequent activation of acid-sensing ion channels (ASICs) may contribute to each of these processes and may thus play a role in migraine pathophysiology. Although few studies have directly examined a role of ASICs in migraine, studies directly examining a connection have generated promising results including efficacy of ASIC blockers in both preclinical migraine models and in human migraine patients. The purpose of this review is to discuss the pathophysiology thought to contribute to migraine and findings that implicate decreased pH and/or ASICs in these events, as well as propose issues to be resolved in future studies of ASICs and migraine. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'.

Autonomic nervous system in the control of energy balance and body weight: personal contributions

The prevalence of obesity is increasing in the industrialized world, so that the World Health Organization considers obesity as a "pandemia" in rich populations. The autonomic nervous system plays a crucial role in the control of energy balance and body weight. This review summarizes our own data and perspectives, emphasizing the influence exerted by autonomic nervous system on energy expenditure and food intake, which are able to determine the body weight. Activation of the sympathetic discharge causes an increase in energy expenditure and a decrease in food intake, while reduction of food intake and body weight loss determines a reduction of the sympathetic activity. On the other hand, pathophysiological mechanisms of the obesity involve alterations of the sympathetic nervous system in accordance with the "Mona Lisa Hypothesis," an acronym for "most obesities known are low in sympathetic activity." Furthermore, the parasympathetic influences on the energy expenditure are analyzed in this review, showing that an increase in parasympathetic activity can induce a paradoxical enhancement of energy consumption.

Procaine into the VMH inhibits IBAT activation caused by frontal cortex stimulation in urethane-anesthetized rats

This experiment tested the effect of procaine injection into the ventromedial hypothalamus on the sympathetic and thermogenic activation induced by frontal cortex stimulation. Oxygen consumption, firing rate of the sympathetic nerves to interscapular brown adipose tissue (IBAT), along with IBAT and colonic temperatures were monitored in fasted male Sprague-Dawley rats before and during 25 min after an electrical stimulation of the frontal cortex. The same variables were monitored in rats with administration of procaine into the ventromedial hypothalamus. The results show that cortical stimulation increases oxygen consumption, sympathetic firing rate, IBAT and colonic temperatures. The increase in sympathetic firing rate was reduced by procaine injection, and the increase in IBAT and colonic temperatures as well as oxygen consumption was fully inhibited by procaine. These findings suggest that the ventromedial nucleus plays an important role in the sympathetic and thermogenic changes induced by cortical stimulation.

Administration of muscimol into the posterior hypothalamus reduces hyperthermia induced by hippocampal neostigmine injection

The firing rate of the sympathetic nerves innervating interscapular brown adipose tissue (IBAT), IBAT and colonic temperatures (T(IBAT) and T(C)) and oxygen (O(2)) consumption were monitored in urethane-anesthetized male Sprague-Dawley rats. These variables were measured for 40 min before (baseline values) and 40 min after an injection of neostigmine (5 x 10(-7) mol in 1 microl of saline) into the hippocampus and a bilateral administration of a GABA(a)-agonist, muscimol (28 ng in 0.5 microl of saline, per side) into the posterior hypothalamus. The same variables were recorded in other rats, but the muscimol was replaced by saline. Control animals were used with muscimol or saline alone. The results show an increase of sympathetic firing rate, T(IBAT), T(C) and O(2) consumption after neostigmine injection. Muscimol significantly reduces this enhancement. The findings suggest that hippocampus controls the sympathetic and thermogenic activation induced by neostigmine through an influence on GABAergic tone of the posterior hypothalamus.