NMDA receptor and nitric oxide synthase activity in the central amygdala is involved in the acquisition and consolidation of conditioned odor aversion.

Rats readily learn to avoid a tasteless odorized solution if they experience visceral malaise after consuming it. This phenomenon is referred to as conditioned odor aversion (COA). Several studies have shown that COA depends on the functional integrity of the amygdala, with most studies focusing on the basolateral nucleus. On the other hand, the role of the central amygdala (CeA) which is known to be involved in the consolidation of conditioned taste aversion (CTA) remains to be established. To address this issue, we evaluated the effect of inhibiting NMDA receptor activity in this structure on COA memory formation. Intra-CeA infusions of non-competitive NMDA receptor inhibitor MK-801 prevented memory formation both when administered before and up to 15 min after COA conditioning, while no effect of this drug was observed when given before long-term memory test. We next evaluated the role of one of the main downstream effectors of brain NMDA receptor signaling, nitric oxide synthase (NOS), known to play a key role in a wide variety learning tasks including some types of olfactory conditioning. Similar results were obtained with inhibition of either NOS or neuron-specific NOS; which proved to be required both during and after COA training, though for a shorter time span than NMDA receptors. Also, neither isoform showed to be required to memory retrieval. These results suggest that the US signaling during acquisition and the initial consolidation step of COA depends on glutamate-NO system activation in the CeA.

Association of stimuli at long intervals in conditioned odor aversion.

Rats learn to avoid a tasteless odorized solution if they experience visceral malaise after consuming it. This phenomenon is referred as Conditioned Odor Aversion (COA). It is widely accepted that an odor can only be associated with illness if the inter-stimulus interval (ISI) is shorter than 15 min. However, this conclusion is based on long-term memory tests usually made 48 h after conditioning, thus precluding the possibility to discriminate between a specific failure to make the odor-malaise association rather than the failure to consolidate the short-term association into long-term memory. In the present study, we compared the short-term and long-term memories for COA in rats trained with long ISIs. Independent groups of male rats were conditioned using 5, 15, 30, 60 or 90 min ISIs and tested either 4 or 48 h after conditioning. We found a reliable odor aversion at 5, 15, 30 and 60 min, but not at 90 min ISIs, when tested 4h after conditioning. In contrast, odor aversion was only found at 5 and 15 min ISIs in the groups tested 48 h after training. Our results show that COA can be acquired when malaise follows the odor CS by at least 60 min. This finding indicates that the lack of aversion at long ISIs is not due to an association failure, but rather to a limitation in consolidating short-term memory into long-term memory of COA.

Niveles séricos de colesterol y lipoproteínas y frecuencia de hipercolesterolemia en un grupo de adolescentes de la Ciudad de México / Cholesterol and lipoprotein levels and hypercholesterolemia in adolescents of the México City

Introducción. El objetivo de este estudio fue determinar los niveles séricos de colesterol y lipoproteinas en un grupo de adolescentes de la Ciudad de México. Material y métodos. Se determinaron niveles séricos de lípidos en un grupo de adolescentes. Se aplicó un cuestionario sobre antecedentes familiares de infarto agudo al miocardio, hipercolesterolemia o diabetes mellitus. Para el análisis estadístico se usó SPSS Y EPI DAT.V3. Resultados. Se estudió a 413 adolescentes, hombres y mujeres, con una edad promedio de 13 años, 14% tenían antecedentes familiares de hipercolesterolemia, 5% de infarto al miocardio y 24.7% de obesidad. El grupo presentó los siguientes valores promedio: colesterol 161 ± 36 mg/dL, triglicéridos 103.9 ± 63 mg/dL, LDL 91.6 ± 58 mg/dL, VLDL 32.3 ± 64 mg/dL y HDL 25.34 mg/dL, sin diferencia significativa entre ambos sexos; 259 (62%) adolescentes presentaron colesterol normal, 102 (24.6%) tuvieron niveles limítrofes altos y 52 (12.6%) hipercolesterolemia. Conclusión. Los niveles de lípidos encontrados muestran un incremento de 10% en el promedio de colesterol, 30% más en la frecuencia de colesterol limítrofe alto y 40% más de hipercolesterolemia en relación a lo reportado en estudios de los últimos 10 años.

Introduction. To know the cholesterol and lipoprotein levels in an adolescents group in Mexico City. Material and methods. We applied a questionnaire about family history of: myocardial infarction, hypercholesterolemia and diabetes mellitus. Cholesterol and lipoproteins measurement were performed in a group of adolescents. SPSS and EPID AT. V3 were used for statistics. Results. Four hundred thirty adolescents were studied, the mean age were 13 years old. We found 14% hypercholesterolemic family history, 5% coronary disease and 24.7% obesity. The mean lipid levels were: cholesterol 161.3 ± 36 mg/dL, triglycerides 103 ± 63 mg/dL, low density lipoprotein 91.6 ± 58 mg/dL, very low density lipoprotein 32.4 ± 64 mg/dL and high density lipoprotein 25.34 mg/dL, there were not difference between male and female; 259 (62%) adolescents presented normal cholesterol levels, 102 (24.6%) high borderline levels and 52 (12.6%) had hypercholesterolemia. Conclusion. The main cholesterol level found was 10% higher, frequency of high borderline cholesterol levels was 30% more and hypercholesterolemia frequency increase 40% in relation to previous reports.