Interaction between repeated restraint stress and concomitant midazolam administration on sweet food ingestion in rats

Emotional changes can influence feeding behavior. Previous studies have shown that chronically stressed animals present increased ingestion of sweet food, an effect reversed by a single dose of diazepam administered before testing the animals. The aim of the present study was to evaluate the response of animals chronically treated with midazolam and/or submitted to repeated restraint stress upon the ingestion of sweet food. Male adult Wistar rats were divided into two groups: controls and exposed to restraint 1 h/day, 5 days/week for 40 days. Both groups were subdivided into two other groups treated or not with midazolam (0.06 mg/ml in their drinking water during the 40-day treatment). The animals were placed in a lighted area in the presence of 10 pellets of sweet food (Froot loops(r)). The number of ingested pellets was measured during a period of 3 min, in the presence or absence of fasting. The group chronically treated with midazolam alone presented increased ingestion when compared to control animals (control group: 2.0 +/- 0.44 pellets and midazolam group: 3.60 +/- 0.57 pellets). The group submitted to restraint stress presented an increased ingestion compared to controls (control group: 2.0 +/- 0.44 pellets and stressed group: 4.18 +/- 0.58 pellets). Chronically administered midazolam reduced the ingestion in stressed animals (stressed/water group: 4.18 +/- 0.58 pellets; stressed/midazolam group: 3.2 +/- 0.49 pellets). Thus, repeated stress increases appetite for sweet food independently of hunger and chronic administration of midazolam can decrease this behavioral effect

Memory consolidation of a habituation task: role of n-methyl-D-aspartate, cholinergic muscarinic and gaba-a receptors in different brain regions

The immediate post-training microinjection of the N-methyl-D-aspartate receptor antagonist amino-5-phosphonopenmtaanoic acid (5 ug) or of scopolamine, the cholinergic muscarinic antagonist (2 ug), into the dorsal hippocampus of rats caused retrograde amnesia for habituation to a novel environment, as measured by the number of rearings and crossings performed in a test session. In contrast, picrotoxin (0.08 ug), the indirect GABA-A antagonist, caused retrograde memory facilitation. Receptor agonist administered into the hippocampus had effects opposite to those of the respective antagonists: glutamate (5 ug) and oxotremorine (2 ug) enhanced memory and muscimol (0.03 ug) was amnestic. Aminophosphonopentanoic acid, scopolamine and picrotoxin had no effect when injected into the amygdala mor medial septum. Our result contrasted with the recent report of an inhibitory avoidance task in which these drugs, at the doses used here, were effective when injected post-training into any of the three structures. These findings suggest that similar neurotransmitter mechanisms operate in different brain regions in order to regulate memory consolidation processes; however, there is a specialization of these brain regions in relation to different types or components of memory

The use of a new non-verbal test in the evaluation of recent memory

A test for recent memory was developed using non-verbal material. The present report describes a series of experiments conducted to evaluate its reproducibility and the influences of changes in the interval between acquisition and tetrieval, and age and level of instruction, and its sensitivity to the integrity of memory function. A total of 114 subjects participated in 5 experiments. The test of recent memory is reproducible over a period of at least 5 months and can be used with training-testing intervals of 24 to 48h. The performance of the test is affected by age and level of instruction. Moreover, thre memory test is sensitive to differences in the integrity of memory function. Thus, the memory test developed in this study may be used to evaluate the effects of behavioral and/or pharmacological manipulations on recent memory in homogeneous groups of subjects