Behavioral and hypothalamic-pituitary-adrenal responses to anterodorsal thalami nuclei lesions and variable chronic stress in maternally separated rats.

In maternally separated rats, variable chronic stress decreased the emotional reactivity and provoked a state of hypoactivity of the hypothalamic-pituitary-adrenal system at 3 months old but increased its activity after the open field test. The anterodorsal thalami nuclei control of the endocrine response under stress conditions was not manifested however its seems activate grooming behavior. The development of behavioral and endocrine response to stress is influenced by early postnatal environment. On the other hand, the anterodorsal thalami nuclei exert an inhibitory influence on the hypothalamic-pituitary-adrenal system under basal and stressful conditions. The aim of this work is to determine the magnitude of behavioral and hypothalamic-pituitary-adrenal responses to variable chronic stress in adult female rats with anterodorsal thalami nuclei lesions, previously isolated for 4.5 h daily during the first 3 weeks of life. The groups were: non-maternally separated sham and lesioned, maternally separated sham and lesioned with variable chronic stress with and without open field test. At 3 months old, under variable chronic stress, maternal separation provoked an increase in ambulation in sham and lesioned animals (P<0.01) but this parameter was not modified by lesion in either non-maternally separated or maternally separated groups. Neither the lesion nor the maternal separation changed the defecation and rearing parameter. Grooming behavior was lower in maternally separated lesioned rats (P<0.05). Under variable chronic stress maternal separation decreased adrenocorticotrophin hormone in comparison with non-maternally separated (P<0.001) and the lesion did not alter this response. Regarding corticosterone concentrations, maternal separation did not affect this hormone under variable chronic stress conditions and after the open field test there was an increase of this in both non-maternally separated and maternally separated sham and lesioned (P<0.001).

Lesion of the bulbospinal noradrenergic pathways blocks desipramine-induced inhibition of the C-fiber evoked nociceptive reflex in rats.

Desipramine-induced inhibition of spinal cord nociceptive transmission was studied in rats with or without lesion of the bulbospinal noradrenergic system by recording the C-fiber evoked nociceptive reflex from a hind limb. Bulbospinal noradrenergic projections were lesioned by injecting intrathecally 20 microg of 6-hydroxydopamine 2 weeks before the electrophysiological experiments. Results show that desipramine (5, 10 and 20 mg/kg intraperitoneally) produced dose-dependent inhibition of the C reflex response duration in rats having intact noradrenergic bulbospinal systems. The inhibitory effect of desipramine was reduced or even abolished in rats pre-treated with 6-hydroxydopamine. In addition, [3H]-noradrenaline uptake was significantly lower in spinal cord slices arising from 6-hydroxydopamine lesioned animals, as compared to that from intact rats. These observations support the notion that the antinociceptive activity of antidepressants with noradrenergic selectivity depends on a normal rate of endogenous noradrenaline released by bulbospinal neurons.

Megacolon: problemas pendientes y alternativas quirurgicas / Megacolon problems to resolve and surgical alternative

Se considera el tema del megacolon chagasico y no chagasico, como una de las patologias mas frecuentes de nuestro pais, señalando un enfoque evolutivo historico que condujo a precisiones etiopatogenicas, los problemas que todavia presiste para una mejor interpretacion y terapeutica y el deseo de sistematizar el comportamiento quirurgico proponiendo alternativas diferentes de acuerdo con algunos factores como las caracteristicas anatomicas individuales del megacolon su etiologia, las condiciones generales del paciente, los distintos grupos etareos en los que se presenta y las situacions de urgencia como el volvulo de asa sigmoide. Se señala tambien la necesidad de realizar investigaciones histopatologicas estadisticamente significativas, de comparacion entre piezas operatorias resecadas por las dos variedades de megacolon correlacionandolas con la informacion epidemiologica, clinica y serologica.