Right and left cortical lesions asymmetrically alter cerebrovascular permeability in the rat

Heartsick: psychiatric and inflammatory implications of cerebromicrovascular disease

BACKGROUND

Cerebromicrovascular disease (CMVD) strikes 87% of the population older than 65 years and is linked to an increased risk of ischemic stroke, depression, cognitive impairment, and Alzheimer's disease. Despite the wealth of knowledge on the consequences to the body stemming from poor vascular health, little focus has been placed on the consequences to the brain.

DESIGN

In this review, we present the preclinical and clinical evidence that supports the role of CMVD in behavioral dysfunction, argues for a clinical need for better recognition of the vascular depression phenotype, and calls for a more integrative translational approach to CMVD.

RESULTS AND CONCLUSIONS

Although the concept of cerebrovascular-induced behavioral change has existed for over 100 years, the difficulty of diagnosis, the slow progression of CMVD, and the lack of causative data have led to an underestimation of the patient population and poor treatment strategies. Preclinical studies have focused on the use of microsphere embolic models and vascular inflammation models to assess the mechanisms of, and treatment options for, CMVD. Though preclinical models provide support for correlative data collected in the clinic, translational reciprocity has not been established. The lack of clinical appreciation for the role of cerebrovascular health in brain function may result in missed diagnoses and inadequate treatment of underlying cardiovascular disease. Enhanced recognition of symptoms and disease presentation will allow for earlier prevention, detection, and identification of novel targets for drug development and other intervention strategies.

Hypoxic hypoxia induces different biochemical changes in the cortex of the right and left hemispheres of rat brain

The activity of acetylcholinesterase (AChE), adenylate cyclase (AC), 5'-nucleotidase (NT), Na+, K(+)-ATPase, as well as the contents of phospholipids (PL) and gangliosides (G) per mg of protein in homogenate, crude membrane (P2) fraction, and synaptosomes from the sensorimotor cortex of the right and left hemispheres of rat brain were analyzed under normal and hypoxic conditions. The authors found that under normal physiological conditions there are no significant differences of the studied parameters in homogenates of sensorimotor cortex from the right and left hemispheres. In P2 fractions, and especially in preparations of synaptosomes from the right and left cortex, differences in the activity of 5'-NT and AC were found. Hypoxia (pO2 = 7.8%) was shown to alter studied parameters (AChE, AC, Na+, K(+)-ATPase activity, and PL content) mainly in the right hemisphere.

Interactions between non-symmetric mechanical vector forces in the body and the autonomic nervous system: basic requirements for any mechanical technique to engender long-term improvements in autonomic function as well as in the functional efficiency of the respiratory, cardiovascular, and brain systems

There are known anatomical asymmetries in the respiratory, cardiovascular, and nervous system. The coupling mechanisms between each of these systems--lungs-heart, heart-brain, and lungs-brain--are also asymmetrical. There is a growing body of literature indicating that mechanical pressure asymmetrically applied to certain areas of the human body produces changes in the balance of autonomic parameters. These findings implicitly indicate that not only magnitude but also the direction and point of application of the force play a role in its influence upon the autonomic nervous system. Therefore, we suggest that asymmetrical vector forces resulting from the mechanical activity of the lungs, heart and blood moving throughout the circulatory system, will also produce a lateralization effect in autonomic balance. We postulate the existence of negative feedback loops between brain autonomic control and mechanical functions in the body as a fundamental part of the body's homeostatic mechanisms. It follows that any mechanical assist to the respiratory or cardiovascular system will be significantly reduced or even eliminated if these homeostatic mechanisms are not taken into account. Our hypothesis predicts that a long-term improvement in autonomic balance as well as in respiratory, cardiovascular, and brain function can be achieved if mechanical forces are applied to the body with the aim of reducing existing imbalances of mechanical force vectors. This technique implies continually controlling for precise timings resulting from physiological periodical forces as well as factors derived from anatomical and coupling asymmetries in the respiratory, cardiovascular, and nervous systems.

Interactions between non-symmetric mechanical vector forces in the body and the autonomic nervous system: basic requirements for any mechanical technique to engender long-term improvements in autonomic function as well as in the functional efficiency of the respiratory, cardiovascular, and brain systems

There are known anatomical asymmetries in the respiratory, cardiovascular, and nervous system. The coupling mechanisms between each of these systems--lungs-heart, heart-brain, and lungs-brain--are also asymmetrical. There is a growing body of literature indicating that mechanical pressure asymmetrically applied to certain areas of the human body produces changes in the balance of autonomic parameters. These findings implicitly indicate that not only magnitude but also the direction and point of application of the force play a role in its influence upon the autonomic nervous system. Therefore, we suggest that asymmetrical vector forces resulting from the mechanical activity of the lungs, heart and blood moving throughout the circulatory system, will also produce a lateralization effect in autonomic balance.

Early effects of right or left cerebral cortex ablation on mitogen-induced spleen lymphocyte DNA synthesis

The cerebral neocortex has been shown to modulate the immune system in an asymmetrical way. In mice, ablation of the left cortex decreases whereas a symmetrical right lesion enhances B and T cell-mediated responses measured at 6-8 weeks after lesioning. In order to study the possibility of neuronal reorganisation during the post-operative period, immunological parameters were determined as early as 2 weeks after right or left cortical ablation. Right lesions depressed lymphocyte DNA synthesis induced by concanavalin A (ConA) and phytohemagglutinin whereas left lesions only depressed ConA-induced blastogenesis. Right or left lesions had no effect on lipopolysaccharide-induced proliferation of B lymphocytes as well as on serum antibody levels. Comparisons between early and late effects of right or left cortical ablation on the immune system showed that each hemicortex differentially modulates lymphocyte subpopulations but also that the neuronal reorganisation following surgery can be different according to the side of cortex lesion.

Continuous infusion of tumor necrosis factor: mechanisms of toxicity in the rat

This study was designed to assess the toxicity of continuous infusion of tumor necrosis factor (TNF) in the rat model. The effect of TNF on cell membranes was assessed by diffusion of radiolabeled inulin (RI). The effect of concomitant administration of the cytoprotectant prostaglandin E1 (PGE1) was also assessed. Eighty rats were anesthetized and two osmotic pumps were implanted in the peritoneal cavity of each rat. One pump contained either TNF (0.1 mg/kg/day) or vehicle and the other either PGE1 (0.1 mcg/kg/min) or vehicle. Four groups resulted: vehicle alone, PGE1 alone, TNF alone, and TNF + PGE1. After 5 days, half of each group received intravenous RI and organ/blood radioactivity ratios were compared at sacrifice 7 min later. Remaining animals had serum drawn for CBC and electrolyte determination. Organ weights were determined in all animals. The effects of TNF and PGE1 were assessed by two-way ANOVA. Mortality in animals infused with TNF was 20%. One animal in the control group died. TNF infusion increased lung weight by 38% (697 +/- 49 vs 937 +/- 77 mg; P less than 0.05). Liver weight was also increased in animals infused with TNF (6.7 +/- 0.2 vs 7.0 +/- 0.3 g; P less than 0.05). TNF infusion increased blood urea nitrogen and decreased serum bicarbonate compared to controls. TNF had no effect on RI diffusion. PGE1 did not alter the response to TNF.

CONCLUSIONS

Continuous infusion of TNF does not affect membrane permeability as assessed by inulin diffusion. PGE1 does not cytoprotect against the toxicity of TNF. Evidence of direct hepatic toxicity suggests that regional therapy via the hepatic artery or portal vein is contraindicated.