Behavior In Aged Rats Research Articles

2231 Effects of the ginseng on place learning behavior in aged rats

2231 Effects of the ginseng on place learning behavior in aged rats

Effects of the subacute administration of nefiracetam on abnormal behavior in aged rats

We investigated the effects of nefiracetam on learning and memory by the Morris water maze task and water-finding test, and on emotional behavior by forced swimming, hole-board and open-field tests in old male Kbl Wistar rats aged 90 and 108 weeks. In the water maze task, the acquisition of the task in aged rats was slower than that in young rats. Subacute administration of nefiracetam (1 and 3 mg/kg daily) for 24 days tended to shorten the goal latency to escape onto the platform in a dose-dependent manner in the retention test, conducted 24 days after acquisition training. Nefiracetam (1 mg/kg) administration for 49 days decreased the duration of immobility in aged rats in the forced swimming test. Locomotor activity in young rats during the dark period was significantly higher than that during the light period, while there was no difference in Locomotor activity between the light and dark periods in aged rats, suggesting that Locomotor activity during the dark period and nocturnal habits may be impaired in aged rats. Subacute administration of nefiracetam for 14 days significantly increased the Locomotor activity during the dark, but not light, period in a dose-dependent manner. In addition, nefiracetam given for 38 days, significantly shortened the increased time elapsed before animals started exploring the environment in aged rats compared with young rats in the water-finding tests. These findings suggest that nefiracetam may improve the impaired nocturnal habits and some of emotional behavior in aged rats.

Kami-untan-to (KUT) improves cholinergic deficits in aged rats

The Effects of the kampo (Japanese herbal) medicine, kami-untan-to (KUT)' on the central cholinergic system and passive avoidance behavior in aged rats (2 years old) were examined. When KUT was orally administered to aged rats, mean latency was significantly increased on passive avoidance test of step through type and choline acetyltransferase (ChAT) activity was increased in the frontoparietal cortex. Oral administration of KUT also increased ChAT mRNA levels in the basal forebrain and nerve growth factor (NGF) mRNA levels in the frontoparietal cortex as demonstrated by the reverse transcription-polymerase chain reaction (RT-PCR) method. These results suggest that oral administration of KUT improves age-related disturbance of memory via increasing effects of ChAT and NGF. KUT may be useful as a potential therapeutic agent in diseases caused by cholinergic deficit such as senile dementia of the Alzheimer type.

Chapter 30: Nerve growth factor affects the cholinergic neurochemistry and behavior of aged rats

The major central cholinergic systems include (1) the projection neurons of the medial septum and diagonal band of Broca (MS/DB) to the hippocampus; (2) the projection neurons of the nucleus basalis magnocellularis (NBM) to the amygdala and cerebral cortex; (3) the inter-neurons of the striatum. Although the basal forebrain projection neurons have been implicated in learning and memory, and the striatal inter-neurons in motor behaviors, it still is not clear how and to what extent the central cholinergic neurons are involved in specific behaviors. Similarly, relatively little is known about the cellular and molecular mechanisms that regulate animal behaviors mediated by the central cholinergic systems. Although acetylcholine (ACh) was the first neurotransmitter discovered in the central nervous system, it remains unclear how the synthesis, storage, and release of ACh are regulated, or how ACh neurochemistry might be altered by environmental stimuli or synaptic experience, both of which would impact on cholinergically mediated behaviors. The central cholinergic systems are particularly dysfunctional in Alzheimer's disease. Thus, our animal research on the regulation of central cholinergic transmission and behavior has focused on the deficits in the systems associated with senescence and the potential amelioration of age-related deficits by the administration of the neurotrophic protein, nerve growth factor (NGF). This chapter describes the current understanding of the regional regulation of ACh synthesis and release in young and old rats, and illustrates several correlations between age-related and NGF-induced alterations in cholinergic neurochemistry, electrophysiology, morphology, and behavior.

Effects of prenatal alcohol exposure on behavior of aged rats

Pregnant rats were intubated with alcohol (3.5 g/kg, twice daily) on gestation days 11–21. Control animals were intubated with an isocaloric sucrose solution and were pair-fed and pair-watered to alcohol-treated dams. At birth, offspring were placed with non-treated surrogate dams. When animals were slightly more than 1 year of age, they were tested for passive avoidance learning, spontaneous alternation and activity. Groups did not differ in passive avoidance learning or spontaneous alteration but animals prenatally exposed to alcohol were more active than controls. Additional studies showed that this increased activity was not affected by testing animals in the presence of environmental stimuli such as objects which could be manipulated, or by odors from mouse shavings from male and female mice.