Modulation of the consolidation and reconsolidation of fear memory by three different serotonin receptors in hippocampus.

The process of memory formation is complex and highly dynamic. During learning, the newly acquired information is found in a fragile and labile state. Through a process known as consolidation, which requires specific mechanisms such as protein synthesis, the memory trace is stored and stabilized. It is known that when a consolidated memory is recalled, it again becomes labile and sensitive to disruption. To be maintained, this memory must undergo an additional process of restabilization called reconsolidation, which requires another phase of protein synthesis. Memory consolidation has been studied for more than a century, while the molecular mechanisms underlying the memory reconsolidation are starting to be elucidated. For this, is essential compare the participation of important neurotransmitters and its receptors in both processes in brain regions that play a central role in the fear response learning. With focus on serotonin (5-HT), a well characterized neurotransmitter that has been strongly implicated in learning and memory, we investigated, in the CA1 region of the dorsal hippocampus, whether the latest discovered serotonergic receptors, 5-HT5A, 5-HT6 and 5-HT7, are involved in the consolidation and reconsolidation of contextual fear conditioning (CFC) memory. For this, male rats with cannulae implanted in the CA1 region received immediately after the training or reactivation session, or 3h post-reactivation of the CFC, infusions of agonists or antagonists of the 5-HT5A, 5-HT6 and 5-HT7 receptors. After 24h, animals were subjected to a 3-min retention test. The results indicated that in the CA1 region of the hippocampus the 5-HT5A, 5-HT6 and 5-HT7 serotonin receptors participate in the reconsolidation of the CFC memory 3h post-reactivation. Additionally, the results suggest that the 5-HT6 and 5-HT7 receptors also participate in the consolidation of the CFC memory.

PACAP modulates the consolidation and extinction of the contextual fear conditioning through NMDA receptors.

Pituitary adenylate cyclase-activating polypeptide (PACAP) has a broad spectrum of biological functions including neurotransmitter, neurotrophic and neuroprotective. Moreover, it has been suggested that PACAP plays a role in the modulation of learning and memory as well as on the modulation of glutamate signaling. Thus, in the current study we investigated in the CA1 region of hippocampus and in the basolateral amygdala (BLA) the role of PACAP in the consolidation and extinction of contextual fear conditioning (CFC) and the interaction between PACAP and NMDA receptors. Male rats with cannulae implanted in the CA1 region of the hippocampus or in the BLA received immediately after the training or extinction training of the CFC infusions of the Vehicle, PACAP-38 (40 pg/side), PACAP 6-38 (40 pg/side) or PACAP 6-38 plus D-serine (50 µg/side). After 24h, the animals were subjected to a 3-min retention test. The results indicated that in the CA1 region of hippocampus, PACAP participates in the consolidation and extinction of the CFC, and in the BLA, PACAP participates only in the consolidation of the CFC. Additionally, the results suggest that the action of PACAP on the consolidation and extinction of the CFC is mediated by the glutamate NMDA receptors.

Exigência nutricional de proteína bruta para codornas japonesas (Coturnix coturnix japonica) na fase de postura / Nutritional requirement of crude protein for japanese quail (Coturnix coturnix japonica) in the production phase

O objetivo do trabalho foi determinar o melhor nível de proteína bruta na alimentação de codornas japonesas em fase de produção. Foram utilizadas 300 codornas com 16 semanas de idade, alojadas em gaiolas, em um delineamento inteiramente casualizado, com cinco tratamentos, seis repetições e dez aves por unidade experimental. Os níveis avaliados foram 14, 17, 20, 23 e 26 por cento de proteína bruta, e as dietas foram formuladas para serem isoenergéticas. Foi verificado efeito quadrático para consumo de ração, peso de ovo, massa de ovo, ingestão de energia, eficiência energética por dúzia de ovo, coeficiente de digestibilidade de nitrogênio, retenção de nitrogênio, peso de gema, casca e albúmen. Efeito linear foi verificado para produção de ovos, ingestão de proteína, conversão alimentar por massa de ovos, eficiência energética por massa de ovo em kg, peso final e gravidade específica. Não houve efeito significativo para conversão alimentar por dúzia e concentração sérica de ácido úrico. Recomenda-se nível de 20 por cento de proteína bruta para codornas japonesas em fase de postura...

The aim of this study was to determine the best level of crude protein in the diet of Japanese quails in the production phase. A total of 300 quails at 16 weeks of age in cages, in a completely randomized design with five treatments and six replicates of ten birds per experimental unit was used. The levels evaluated were 14, 17, 20, 23 and 26 percent crude protein and diets were formulated to be isoenergetic. A quadratic effect was observed for feed intake, egg weight, egg mass, energy intake, energy efficiency per dozen eggs, nitrogen digestibility, shell percentage, nitrogen retention, weight of yolk, albumen and shell. A linear effect was observed for egg production, protein intake, feed conversion by egg mass, energy efficiency per egg mass in kg, final weight and yolk percentage and specific gravity. There was no significant effect on feed conversion per dozen, percentage of albumen, shell thickness and serum uric acid. The recommendation is of a 20 percent crude protein level for Japanese quail during the laying phase...