Fish oil improves anxiety-like, depressive-like and cognitive behaviors in olfactory bulbectomised rats.

Depression is increasingly present in the population, and its pathophysiology and treatment have been investigated with several animal models, including olfactory bulbectomy (Obx). Fish oil (FO) supplementation during the prenatal and postnatal periods decreases depression-like and anxiety-like behaviors. The present study evaluated the effect of FO supplementation on Obx-induced depressive-like behavior and cognitive impairment. Female rats received supplementation with FO during habituation, mating, gestation, and lactation, and their pups were subjected to Obx in adulthood; after the recovery period, the adult offspring were subjected to behavioral tests, and the hippocampal levels of brain-derived neurotrophic factor (BDNF), serotonin (5-HT) and the metabolite 5-hydroxyindoleacetic (5-HIAA) were determined. Obx led to increased anxiety-like and depressive-like behaviors, and impairment in the object location task. All behavioral changes were reversed by FO supplementation. Obx caused reductions in the levels of hippocampal BDNF and 5-HT, whereas FO supplementation restored these levels to normal values. In control rats, FO increased the hippocampal level of 5-HT and reduced that of 5-HIAA, indicating low 5-HT metabolism in this brain region. The present results indicate that FO supplementation during critical periods of brain development attenuated anxiety-like and depressive-like behaviors and cognitive dysfunction induced by Obx. These results may be explained by increased levels of hippocampal BDNF and 5-HT, two major regulators of neuronal survival and long-term plasticity in this brain structure.

Motor and non-motor features of Parkinson's disease - a review of clinical and experimental studies.

Classically, Parkinson's disease (PD) is considered to be a motor system affliction and its diagnosis is based on the presence of a set of cardinal motor signs (e.g. rigidity, bradykinesia, rest tremor and postural reflex disturbance). However, there is considerable evidence showing that non-motor alterations (e.g. anxiety, depression, sleep, gastrointestinal and cognitive functions) precede the classical motor symptoms seen in PD. The management of these nonmotor symptoms remains a challenge. A pattern of regional neurodegeneration that varies considerably depending upon the neuronal population affected may explain the different symptoms. In fact, differential mechanisms of neuronal vulnerability within the substantia nigra pars compacta (SNpc) suggests that factors other than location contribute to the susceptibility of these neurons. In this review we discuss how these factors interact to ultimately target the SNpc. Remarkably, this region consists of approximately 95% of the tyrosine hydroxylase (TH)-immunoreactive neurons in both human and rat brains, and consequently this implicates elevated levels of dopamine metabolites, free radicals and other hazard species in these neurons. An understanding of how these factors promote neuronal death may be useful for the development of novel neuroprotective and/or neurorestorative strategies for PD.

Middle-aged, but not young, rats develop cognitive impairment and cortical neurodegeneration following the four-vessel occlusion/internal carotid artery model of chronic cerebral hypoperfusion.

Permanent, stepwise occlusion of the vertebral arteries (VAs) and internal carotid arteries (ICAs) following the sequence VA→ICA→ICA, with an interstage interval (ISI, →) of 7 days, has been investigated as a four-vessel occlusion (4-VO)/ICA model of chronic cerebral hypoperfusion. This model has the advantage of not causing retinal damage. In young rats, however, 4-VO/ICA with an ISI of 7 days fails to cause behavioral sequelae. We hypothesized that such a long ISI would allow the brain to efficiently compensate for cerebral hypoperfusion, preventing the occurrence of cognitive impairment and neurodegeneration. The present study evaluated whether brain neurodegeneration and learning/memory deficits can be expressed by reducing the length of the ISI and whether aging influences the outcome. Young, male Wistar rats were subjected to 4-VO/ICA with different ISIs (5, 4, 3 or 2 days). An ISI of 4 days was used in middle-aged rats. Ninety days after 4-VO/ICA, the rats were tested for learning/memory impairment in a modified radial maze and then examined for neurodegeneration of the hippocampus and cerebral cortex. Regardless of the ISI, young rats were not cognitively impaired, although hippocampal damage was evident. Learning/memory deficits and hippocampal and cortical neurodegeneration occurred in middle-aged rats. The data indicate that 4-VO/ICA has no impact on the capacity of young rats to learn the radial maze task, despite 51% hippocampal cell death. Such resistance is lost in middle-aged animals, for which the most extensive neurodegeneration observed in both the hippocampus and cerebral cortex may be responsible.

Long-term treatment with fish oil prevents memory impairments but not hippocampal damage in rats subjected to transient, global cerebral ischemia.

Cerebral ischemia leads to neurodegeneration and cognitive impairment. Fish oil (FO) constitutes a rich dietary source of omega-3 polyunsaturated fatty acids especially docosahexaenoic acid (DHA). The objective of the present study was to investigate whether long-term treatment with commercial, high concentration DHA-containing FO could be effective in alleviating both the cognitive and neurodegenerative deficits caused by transient, global cerebral ischemia (TGCI) in rats. Naive rats were trained for 10 days in an 8-arm radial maze task and then subjected to TGCI for 15 minutes (4-VO model) 3 days later (day 13). Retention of the previously acquired cognition (ie, memory) was assessed weekly on days 20, 27, 34, 41, 48, and 55 and measured by 3 behavioral parameters as follows: (i) latency to find the goal box, (ii) number of reference memory errors, and (iii) number of working memory errors. The extent of pyramidal cell death in the hippocampus was examined at the end of the behavioral analysis on day 43. Fish oil (300 mg/kg DHA, gavage) administration occurred once daily beginning 3 days before TGCI (the last day of training) and continued until day 41. Transient, global cerebral ischemia markedly disrupted memory performance measured by all 3 parameters (P < .0001 vs sham). This amnesic effect of ischemia persisted until the end of the behavioral analysis. Treatment with FO progressively reversed the TGCI-induced retention deficit until rats achieved control levels. This protective effect of FO on learning/memory function was clearly observed after both daily and cumulative data analysis (P < .001-0.01 vs vehicle). Such memory improvements remained statistically significant, even after cessation of FO treatment, indicating a sustained effect of FO. In contrast, FO failed to prevent ischemia-induced hippocampal damage in areas CA1, CA2, or CA4. Therefore, the present findings suggest that long-term FO treatment is able to facilitate functional recovery after ischemic brain damage, an effect that was distinct from hippocampal damage.