Partial aortic ligature induces selective long-term c-fos like immunoreactivity in the organum vasculosum of the lamina terminalis, medial preoptic area and choroid plexus in the rat

c-fos induction in the choroid plexus, tanycytes and pars tuberalis is an early indicator of spontaneous arousal from torpor in a deep hibernator

Hibernation is an extreme state of seasonal energy conservation, reducing metabolic rate to as little as 1% of the active state. During the hibernation season, many species of hibernating mammals cycle repeatedly between the active (aroused) and hibernating (torpid) states (T-A cycling), using brown adipose tissue (BAT) to drive cyclical rewarming. The regulatory mechanisms controlling this process remain undefined but are presumed to involve thermoregulatory centres in the hypothalamus. Here, we used the golden hamster (Mesocricetus auratus), and high-resolution monitoring of BAT, core body temperature and ventilation rate, to sample at precisely defined phases of the T-A cycle. Using c-fos as a marker of cellular activity, we show that although the dorsomedial hypothalamus is active during torpor entry, neither it nor the pre-optic area shows any significant changes during the earliest stages of spontaneous arousal. Contrastingly, in three non-neuronal sites previously linked to control of metabolic physiology over seasonal and daily time scales - the choroid plexus, pars tuberalis and third ventricle tanycytes - peak c-fos expression is seen at arousal initiation. We suggest that through their sensitivity to factors in the blood or cerebrospinal fluid, these sites may mediate metabolic feedback-based initiation of the spontaneous arousal process.

Maternal pregnancy vomiting and offspring salt taste sensitivity and blood pressure

The purpose of this study was to investigate the relationship between salt taste perception and blood pressure (BP) in normotensive adolescents as modified by maternal fluid losses during the first trimester of gestation. Seventy-two healthy adolescents (42 boys) aged between 9.0-21.1 years, recruited from the population-based RICARDIN study, were included. A maternal questionnaire about the duration of pregnancy, birth weight and vomiting or diarrhoea in the first trimester of gestation was collected. The sample was categorized into: "vomiter descendents", those whose mother reported significant vomiting in the first trimester of gestation and "non-vomiter descendents" the remaining. Height, weight, and standardised BP measurement were recorded. Salt gustatory performance was assessed using a behavioral sensitivity test to determine the lower NaCl gustatory threshold, and a behavioral discrimination test, measuring the ability to distinguish among different saline solutions. Salt taste sensitivity showed a significant correlation with systolic BP (SBP) in "vomiter descendents" ( r = -0.66; P =0.003), but not in "non-vomiter descendents". Adjusted by gender, and actual height and weight, salt sensitivity performance remained significantly related to SBP. An association between descendents' SBP and maternal vomiting during gestation exists, adding a new element of evidence to the "Barker hypothesis".

Quantitative histochemical assessment of oxidative metabolism in the subfornical organ after partial aortic ligature in rats

Circumventricular organs are considered to be involved in hydromineral homeostatic responses. In this study we used quantitative histochemistry of cytochrome oxidase to evaluate the oxidative metabolic activity of the subfornical organ of rats with a partial aortic occlusion. These rats showed a significant increase in water intake from the second day after the ligature, while natriophilia was already significant on the first day. Greater levels of cytochrome oxidase activity were found in subfornical organs of partial aortic ligated rats when compared with control, providing further evidence for the involvement of this circumventricular structure in fluid homeostasis at least in this hyperdipsic, hypernatriophilic, hyperreninemic and hypertensive experimental model.