Effects of electrolytic lesion of medial septum on some immune responses in rats

Vitamin E Reduces Hypobaric Hypoxia-Induced Immune Responses in Male Rats

In hypobaric hypoxia (HH) at high altitude, the immune responses are changed probably due to oxidative stress-induced production of free radicals and nonradicals. Vitamin E is an antioxidant and protects the cells from oxidative damage. The present study was carried out to study the antioxidant role of vitamin E on the immune changes induced by oxidative stress in HH at high altitude. Select immune responses (phagocytic activity of white blood cell [WBC], cytotoxic activity of splenic mononuclear cells [MNCs], and delayed type of hypersensitivity [DTH]) and hematological changes (total count and differential count [DC] of WBC) were measured in male rats exposed to intermittent HH (at 5486.4 m in a simulated chamber for 8 hours/d for 6 consecutive days) and in normobaric condition with and without p.o. administration of vitamin E in three different doses (20, 40, and 60 mg/kg body weight). The increase of phagocytic activity of blood WBC, and reduction of cytotoxic activity of splenic MNC and DTH response were observed in rats exposed to HH. After the administration of vitamin E at different doses, the immune changes were blocked in a dose-dependent manner. Exposure to HH also led to the elevation of serum corticosterone (CORT), which was arrested after administration of vitamin E. The results indicate that the immune changes in HH at high altitude are probably mediated by the production of free radicals and nonradicals, and vitamin E can block these immune changes by its reactive oxygen species quenching effects.

Effects of stimulation of muscarinic acetylcholine receptors in medial septum on some immune responses in rats

OBJECTIVES

Though the immunomodulatory role of medial septum (MS) has been indicated, but the contribution of the muscarinic acetylcholine (mAch) receptors presented in the internal network of the neurons of MS in this regard is not known. The aim of the present study is to assess the contribution of mAch receptors of MS on some immunological parameters.

METHODS

Different immunological parameters i.e. phagocytic activity of peripheral leukocytes, adhesibility and cytotoxicity of splenic mononuclear cells (MNC), delayed type of hypersensitivity (DTH) responses, Total Count (TC) and Differential Count (DC) of WBC with serum corticosterone (CORT) concentration have been measured after stimulation and blocking of mAch receptors of MS in rats. Ach or atropine has been micro infused into MS of separate groups of rats for stimulating or blocking of the mAch receptors respectively.

RESULTS

In Ach or atropine microinfused rats, the TC of WBC remained unaltered in the present study. The percentage of neutrophil has increased and the percentage of lymphocyte has decreased in Ach microinfused rats, but these parameters remain unaltered in atropine microinfused rats. The observed immunological parameters have increased after microinfusion of 0.60μM and 0.12μM of Ach and serum CORT concentration has decreased in those animals. These immunological parameters have decreased and serum CORT has increased after microinfusion of atropine (2 and 4mM) in MS of rats.

CONCLUSION

It appears that the Ach receptors in MS can modulate the observed immunological parameters, and serum CORT plays an important role for these immune changes.

Effects of vitamin C on the hypobaric hypoxia-induced immune changes in male rats

Hypobaric hypoxia (HH) induces oxidative stress (OS) and is associated with the generation of reactive oxygen species (ROS). Vitamin C is an efficient antioxidant, and it is used in a high-altitude environment to reduce the OS. The present study explores the role of vitamin C on some HH-induced changes of immune parameters in rats which were exposed to HHc condition at 18,000 ft in a simulated chamber for 8 h/day for 6 days with and without vitamin C administration at three different doses (200, 400, and 600 mg/kg body wt). The phagocytic activity of circulating blood WBC was increased, and the cytotoxic activity of splenic mononuclear cell (MNC) and the delayed type of hypersensitivity (DTH) responses to bovine serum albumin (BSA) were decreased in rats exposed to HHc condition, but these immune changes were blocked after administration of vitamin C at 400 mg/kg body wt. The leukocyte adhesive inhibition index (LAI) was not altered either in HHc condition or after administration of vitamin C in HHc condition. The serum corticosterone (CORT) concentration was increased in rats exposed to HHc condition which was blocked after administration of vitamin C (400 mg/kg body wt). The immune parameters and serum CORT concentration, however, did not show any recovery after administration of vitamin C at the dose of 200 and 600 mg/kg body wt. The present study indicates that administration of vitamin C at a dose of 400 mg/kg body wt may prevent the HH-induced immunological changes but not at the lower dose (200 mg/kg body wt) or higher dose (600 mg/kg body wt) in rats.

Effects of naproxen on immune responses in a colchicine-induced rat model of Alzheimer's disease

BACKGROUND

The components of the immune system have been indicated to be linked with the neurotoxicity in Alzheimer's disease (AD). The participation of the immune system in the neurodegeneration in a rat model of colchicine-induced AD has not been explored.

METHODS

In the present study, hippocampal neurodegeneration along with reactive oxygen species (ROS), nitrite and TNF-α in the hippocampus and some systemic immune responses were measured after 15 and 21 days of intracerebroventricular colchicine injection in rats and again after oral administration of different doses of the anti-inflammatory drug naproxen in AD rats.

RESULTS

Chromatolysis and amyloid plaques were found along with higher ROS, nitrite and TNF-α levels in the hippocampus of colchicine-induced AD rats, and these changes were prevented by naproxen in a dose-dependent manner. Alterations in immunological parameters [increased phagocytic activity of white blood cells and splenic polymorphonuclear cells (PMN), increased cytotoxicity and decreased leucocyte adhesive inhibition index (LAI) of splenic mononuclear cells (MNC)] were also observed in colchicine-injected rats, which showed a dose-dependent recovery after oral administration of naproxen in AD rats. The number of plaques, chromatolysis of Nissl granules, TNF-α, nitrite and ROS levels in the hippocampus, phagocytic activity of splenic PMN and LAI of splenic MNC in AD rats showed greater changes in the 21- than in the 15-day study, and the recovery of these parameters after administration of naproxen differed between the two study durations.

CONCLUSION

The present study shows that colchicine-induced neurodegeneration is time dependent and mediated by cyclooxygenase-induced neuroinflammation, which is reflected in the systemic immunological responses.