Early free access to hypertonic NaCl solution induces a long-term effect on drinking, brain cell activity and gene expression of adult rat offspring.

Exposure to an altered osmotic environment during a pre/postnatal period can differentially program the fluid intake and excretion pattern profile in a way that persists until adulthood. However, knowledge about the programming effects on the underlying brain neurochemical circuits of thirst and hydroelectrolyte balance, and its relation with behavioral outputs, is limited. We evaluated whether early voluntary intake of hypertonic NaCl solution may program adult offspring fluid balance, plasma vasopressin, neural activity, and brain vasopressin and angiotensinergic receptor type 1a (AT1a)-receptor gene expression. The manipulation (M) period covered dams from 1 week before conception until offspring turned 1-month-old. The experimental groups were (i) Free access to hypertonic NaCl solution (0.45 M NaCl), food (0.18% NaCl) and water [M-Na]; and (ii) Free access to food and water only [M-Ctrol]. Male offspring (2-month-old) were subjected to iv infusion (0.15 ml/min) of hypertonic (1.5M NaCl), isotonic (0.15M NaCl) or sham infusion during 20 min. Cumulative water intake (140 min) and drinking latency to the first lick were recorded from the start of the infusion. Our results indicate that, after systemic sodium overload, the M-Na group had increased water intake, and diminished neuronal activity (Fos-immunoreactivity) in the subfornical organ (SFO) and nucleus of the solitary tract. They also showed reduced relative vasopressin (AVP)-mRNA and AT1a-mRNA expression at the supraoptic nucleus and SFO, respectively. The data indicate that the availability of a rich source of sodium during the pre/postnatal period induces a long-term effect on drinking, neural activity, and brain gene expression implicated in the control of hydroelectrolyte balance.

Determinacion de triptofano en suero total y en una fraccion precipitada con sulfato de amonio. / Determination of tryptophan in total serum and in an ammonium sulfate precipitated fraction

En este articulo se describe un procedimiento alternativo para investigar los niveles de triptofano libre en suero sanguineo. Para esto, se determinaron mediante un metodo fluorometrico la concentracion de triptofano en suero total y en fracciones precipitadas con sulfato de amonio a 30, 35, 40, 45, 50 y 55 por ciento de saturacion. La concentracion de triptofano en suero total fue siempre mayor que la de las fracciones estudiadas. Se encontrarion pocas variaciones entre la concentracion de triptofano en las fracciones que se obtuvieron a 30, 35 y 40 por ciento de saturacion se observo un ligero incremento en el contenido de triptofano. Los datos obtenidos sugieren que, a partir de estas mediciones, se puede determinar con precision y relativa facilidad el contenido de triptofano libre en suero