Intrahippocampal spermidine administration improves inhibitory avoidance performance in rats.

Polyamines are polycations present at high concentrations in the mammalian brain. We investigated the effect of an intrahippocampal infusion of spermidine, a polyamine agonist, immediately post-training on the inhibitory avoidance learning paradigm in rats. Bilateral intrahippocampal microinjection of spermidine (0.02-20 nmol) caused an increase in test step-down latencies at low concentrations. Administration of arcaine (0.002-0.2 nmol), an antagonist of the N-methyl-D-aspartate (NMDA) receptor polyamine binding site, did not modify the test step-down latencies. In contrast, co-administration of arcaine and spermidine completely reversed the facilitatory effect of spermidine on the test step-down latencies. These results provide evidence that polyamines may be involved in learning and memory modulation.

[Late-presenting congenital diaphragmatic hernia: a possible cause of sudden respiratory distress in children] / Hérnia diafragmática congênita de apresentação tardia: uma possível causa de dificuldade respiratória aguda na criança.

OBJECTIVE: To emphasize that congenital defects of the diaphragm should be considered in the differential diagnosis of sudden onset of respiratory distress in children. MATHOD: Two illustrative cases of children (aged 2 years) with late presenting congenital diaphragmatic hernia who developed sudden respiratory distress and were managed at the University Hospital of Santa Maria are reported. The medical literature was reviewed to identify cases reports and other articles related to late presenting congenital diaphragmatic hernia. A computerized search was performed using the MEDLINE data base to identify papers published within the last 25 years. RESULTS: In both cases the initial clinical examination and plain chest X-rays were misinterpreted as another pleuropulmonary disease like pneumothorax/pneumatoceles. One of the children underwent to emergency chest tube placement without clinical improvement. The absence of respiratory symptoms that could justify this kind of pathology motivated a more careful investigation, involving fiberoptical endoscopy and intestinal seriography. This subsequent investigation revealed that the cause was late-presenting congenital diaphragmatic hernia. CONCLUSION: Although many congenital diaphragmatic hernias that present late have a history of chronic respiratory symptoms, some of them present with acute symptoms. A higher degree of attention is required to avoid confusion with other intrathoracic conditions, such as pneumatoceles and pneumothorax, if an incorrect diagnosis is to be avoided. Misinterpretation of the radiographs is likely if the possibility of a congenital diaphragmatic hernia is not considered, and may result in increased morbidity. Gastric atony may occur in the early postoperative period.

Intrahippocampal GMP administration improves inhibitory avoidance performance through GABAergic and glutamatergic mechanisms in rats.

Guanidino compounds play specific physiological and pathological roles in the central nervous system. We investigated the effect of an intrahippocampal infusion of GMP (a guanidino compound) administered immediately post-training on the inhibitory avoidance learning paradigm in rats. Bilateral intrahippocampal micro-injection of GMP (0-30 nmol) caused a dose-dependent increase in test step-down latencies which was completely reversed by intrahippocampal co-administration of muscimol or baclofen (GABA agonists) or preadministration (15 min pre-training, i.p.) of MK-801 (an NMDA antagonist). These results provide evidence for a participation of GABA and NMDA receptors in the GMP-induced increase in the test step-down latencies.