Environmental enrichment improves cognitive function, learning, memory and anxiety-related behaviours in rodent models of dementia: Implications for future study.

Environmental enrichment (EE) is a process of brain stimulation by modifying the surroundings, for example, by changing the sensory, social, or physical conditions. Rodents have been used in such experimental strategies through exposure to diverse physical, social, and exploration conditions. The present study conducted an extensive analysis of the existing literature surrounding the impact of EE on dementia rodent models. The review emphasised the two principal aspects that are very closely related to dementia: cognitive function (learning and memory) as well as psychological factors (anxiety-related behaviours such as phobias and unrealistic worries). Also highlighted were the mechanisms involved in the rodent models of dementia showing EE effects. Two search engines, PubMed and Science Direct, were used for data collection using the following keywords: environmental enrichment, dementia, rodent model, cognitive performance, and anxiety-related behaviour. Fifty-five articles were chosen depending on the criteria for inclusion and exclusion. The rodent models with dementia demonstrated improved learning and memory in the form of hampered inflammatory responses, enhanced neuronal plasticity, and sustained neuronal activity. EE housing also prevented memory impairment through the prevention of amyloid beta (Aß) seeding formation, an early stage of Aß plaque formation. The rodents subjected to EE were observed to present increased exploratory activity and exert less anxiety-related behaviour, compared to those in standard housing. However, some studies have proposed that EE intervention through exercise would be too mild to counteract the anxiety-related behaviour and risk assessment behaviour deficits in the Alzheimer's disease rodent model. Future studies should be conducted on old-aged rodents and the duration of EE exposure that would elicit the greatest benefits since the existing studies have been conducted on a range of ages and EE durations. In summary, EE had a considerable effect on dementia rodent models, with the most evident being improved cognitive function.

Pubertal anabolic androgenic steroid exposure in male rats affects levels of gonadal steroids, mating frequency, and pregnancy outcome.

Background Testosterone, nandrolone, and stanozolol are among the highly consumed anabolic androgenic steroids (AASs). Although the desired effects of AAS are being achieved by the abusers, unfortunately, this leads to numerous physical and physiological side effects. The present study was designed to investigate and determine whether early pubertal exposure to AAS treatment had detrimental effects on blood testosterone and estradiol concentrations, mating behavior, and pregnancy outcome during the pubertal period in male rats. Materials Early pubertal rats (PND41) were given two doses (2.5 mg/kg and 5 mg/kg) each of testosterone, nandrolone, and stanozolol subcutaneously for 6 weeks. Upon completion, three rats with the highest weight were chosen from each group for mating with the females, in a ratio of one male to two females for 10 days. After 10 days, all male rats were sacrificed to obtain the testes for weight recording, and blood samples were collected for testosterone and estradiol quantitation. Pregnant females were housed separately until birth, and the number of offsprings produced was counted. Results The results clearly show a reduction in reproductive hormonal and behavioral parameters between testosterone and nandrolone, and testosterone and stanozolol. Stanozolol administration exhibited suppressing effects in all parameters including testicular weight deterioration, serum testosterone and estradiol reduction, low mating preferences, and declined pregnancy outcome. Conclusions AAS exposure during the onset of puberty results in reproductive detrimental effects, which are postulated to affect the pregnancy rate.

Histological changes in testes of rats treated with testosterone, nandrolone, and stanozolol.

BACKGROUND: Anabolic androgenic steroids (AAS) is being used in medical treatments, but AAS also was identified to have the risks of adverse effects towards patients and consumers health. OBJECTIVE: Present study was conducted to observe the effects of testosterone, nandrolone, and stanozolol (forms of AAS) intake during onset of puberty on the rat testicular histology. MATERIALS AND METHODS: Juvenile male Sprague-Dawley (SD) rats (n=42) were divided into seven groups and were injected subcutaneously with medium dose of polyethylene glycol-200 (PEG-200) (control), testosterone, nandrolone, and stanozolol for six weeks (PND 41-87). The animals were weighed daily and sacrificed on PND 88. Testes were removed, weighed, and prepared for histological assessment and finally specimens were observed under microscope. RESULTS: The results showed an insignificant increase in mean daily body weight with highest and lowest body weight gained was of 177.6±1.69 gr and 140.0±12.26 gr respectively. There was significant decrease in the testes absolute weight (p≤0.01) in all experimental groups except in the nandrolone 2.5 mg/kg/week treated group. Testicular histology of rats treated with AAS also showed slight changes in the uniformity of arrangements of seminiferous tubules. CONCLUSION: Data from present study suggests that AAS have been initiating the adverse effects on testicular normal functions in rats during onset of puberty.