Feline bone marrow-derived mesenchymal stromal cells (MSCs) show similar phenotype and functions with regards to neuronal differentiation as human MSCs.

Mesenchymal stromal cells (MSCs) show promise for treatment of a variety of neurological and other disorders. Cat has a high degree of linkage with the human genome and has been used as a model for analysis of neurological disorders such as stroke, Alzheimer's disease and motor disorders. The present study was designed to characterize bone marrow-derived MSCs from cats and to investigate the capacity to generate functional peptidergic neurons. MSCs were expanded with cells from the femurs of cats and then characterized by phenotype and function. Phenotypically, feline and human MSCs shared surface markers, and lacked hematopoietic markers, with similar morphology. As compared to a subset of human MSCs, feline MSCs showed no evidence of the major histocompatibility class II. Since the literature suggested Stro-1 as an indicator of pluripotency, we compared early and late passages feline MSCs and found its expression in >90% of the cells. However, the early passage cells showed two distinct populations of Stro-1-expressing cells. At passage 5, the MSCs were more homogeneous with regards to Stro-1 expression. The passage 5 MSCs differentiated to osteogenic and adipogenic cells, and generated neurons with electrophysiological properties. This correlated with the expression of mature neuronal markers with concomitant decrease in stem cell-associated genes. At day 12 induction, the cells were positive for MAP2, Neuronal Nuclei, tubulin ßIII, Tau and synaptophysin. This correlated with electrophysiological maturity as presented by excitatory postsynaptic potentials (EPSPs). The findings indicate that the cat may constitute a promising biomedical model for evaluation of novel therapies such as stem cell therapy in such neurological disorders as Alzheimer's disease and stroke.

Role of IL-1 beta and 5-HT2 receptors in midbrain periaqueductal gray (PAG) in potentiating defensive rage behavior in cat.

Feline defensive rage, a form of aggressive behavior that occurs in response to a threat can be elicited by electrical stimulation of the medial hypothalamus or midbrain periaqueductal gray (PAG). Our laboratory has recently begun a systematic examination of the role of cytokines in the regulation of rage and aggressive behavior. It was shown that the cytokine, interleukin-2 (IL-2), differentially modulates defensive rage when microinjected into the medial hypothalamus and PAG by acting through separate neurotransmitter systems. The present study sought to determine whether a similar relationship exists with respect to interleukin 1-beta (IL-1 beta), whose receptor activation in the medial hypothalamus potentiates defensive rage. Thus, the present study identified the effects of administration of IL-1 beta into the PAG upon defensive rage elicited from the medial hypothalamus. Microinjections of IL-1 beta into the dorsal PAG significantly facilitated defensive rage behavior elicited from the medial hypothalamus in a dose and time dependent manner. In addition, the facilitative effects of IL-1 beta were blocked by pre-treatment with anti-IL-1 beta receptor antibody, while IL-1 beta administration into the PAG had no effect upon predatory attack elicited from the lateral hypothalamus. The findings further demonstrated that IL-1 beta's effects were mediated through 5-HT(2) receptors since pretreatment with a 5-HT(2C) receptors antagonist blocked the facilitating effects of IL-1 beta. An extensive pattern of labeling of IL-1 beta and 5-HT(2C) receptors in the dorsal PAG supported these findings. The present study demonstrates that IL-beta in the dorsal PAG, similar to the medial hypothalamus, potentiates defensive rage behavior and is mediated through a 5-HT(2C) receptor mechanism.

The neurobiological bases for development of pharmacological treatments of aggressive disorders.

Violence and aggression are major causes of death and injury, thus constituting primary public health problems throughout much of the world costing billions of dollars to society. The present review relates our understanding of the neurobiology of aggression and rage to pharmacological treatment strategies that have been utilized and those which may be applied in the future. Knowledge of the neural mechanisms governing aggression and rage is derived from studies in cat and rodents. The primary brain structures involved in the expression of rage behavior include the hypothalamus and midbrain periaqueductal gray. Limbic structures, which include amygdala, hippocampal formation, septal area, prefrontal cortex and anterior cingulate gyrus serve important modulating functions. Excitatory neurotransmitters that potentiate rage behavior include excitatory amino acids, substance P, catecholamines, cholecystokinin, vasopressin, and serotonin that act through 5-HT(2) receptors. Inhibitory neurotransmitters include GABA, enkephalins, and serotonin that act through 5-HT(1) receptors. Recent studies have demonstrated that brain cytokines, including IL-1beta and IL-2, powerfully modulate rage behavior. IL-1-beta exerts its actions by acting through 5-HT(2) receptors, while IL-2 acts through GABAA or NK(1) receptors. Pharmacological treatment strategies utilized for control of violent behavior have met with varying degrees of success. The most common approach has been to apply serotonergic compounds. Others included the application of antipsychotic, GABAergic (anti-epileptic) and dopaminergic drugs. Present and futures studies on the neurobiology of aggression may provide the basis for new and novel treatment strategies for the control of aggression and violence as well as the continuation of existing pharmacological approaches.

Amygdaloid kindled seizures can induce functional and pathological changes in thymus of rat: role of the sympathetic nervous system.

The present study sought to determine the effects of long-term kindled seizures of the basal amygdala upon immune function in rat, utilizing the thymus, as a principal target for study. Histopathology from kindled Sprague-Dawley rats revealed the presence of epithelial cell thymoma in 70% of these rats. The results revealed an increased rate of apoptosis and proliferation in thymic epithelial cells. Analysis of thymocytes indicated a decrease in the ratio of CD4 to CD8 positive T cells and reduced proliferative response to T-cell mitogens. To determine whether these effects were mediated through the sympathetic nervous system, animals were treated with guanethidine, which blocked the development of epithelial cell thymomas, while mifepristone treatment, employed to determine the possible role of the hypothalamic-pituitary axis, was ineffective in attenuating thymoma development. Thus, the present study demonstrated that functional and pathological changes in the thymus during kindled seizures are mediated through the sympathetic nervous system.

Long-term kindled seizures induce alterations in hematopoietic functions: role of serum leptin.

Recent studies conducted in our laboratory have demonstrated marked increases in both serum leptin levels and colony numbers in bone marrow progenitor cells following long-term kindled seizures in rats. The present study sought to determine whether such changes in hematopoietic functions following kindling are linked to increased serum leptin levels. Kindled stage V seizures were induced for 30 days in Sprague-Dawley rats by stimulation of the basal complex of amygdala. The results revealed colony numbers in colony forming units-granulocyte/macrophage (CFU-GM) cultures from kindled rats increased significantly, an effect that was blocked by the presence of an anti-leptin antibody. The results further demonstrated that the addition of serum obtained from kindled rats to CFU-GM cultures from control rats significantly increased the numbers of colonies relative to non-serum added cultures. Moreover, the proliferative effects of serum from kindled rats were also blocked by adding an anti-leptin antibody. These findings were confirmed from the observations that the long isoform of the leptin receptor, which is capable of signal transduction, was present only in kindled, but not in control rats. Thus, the results provide evidence that the hematopoietic changes observed following long-term kindling are directly associated with elevated serum leptin levels.

Effects of kindled seizures upon hematopoiesis in rats.

OBJECTIVE: Studies conducted in epilepsy patients and experimental animals have suggested a linkage between seizure activity and alterations in immune functions. However, little is known about the underlying mechanisms. The present study sought to determine whether chronic seizures result in changes in hematopoietic functions that contribute to alterations in immune function. MATERIALS AND METHODS: Sprague-Dawley rats were implanted with electrodes in the basal amygdala or frontal cortex for induction of focal seizures by kindling. After inducing stage 5 seizures for 30 days, rats were sacrificed and assays for colony-forming units granulocyte/macrophage (CFU-GM) were performed to study progenitor cell functions. Long-term culture-initiating culture (LTC-IC) assays were employed to determine the effects of kindling upon bone marrow stroma. A Western blot for caspase-3 and CFU-GM assays from peripheral blood were used to determine the cause of reduced cellularity of bone marrow. RESULTS: Kindled seizures of the basal amygdala resulted in decreases in bone marrow cellularity and hyperproliferation of colony-forming cells in peripheral blood and bone marrow. Modified LTC-IC assays, where co-cultures of bone marrow cells and stroma from experimental animals were employed, revealed that hyperproliferation of progenitor cells was not associated with alterations in stromal functions. The changes observed in this study were associated with seizure foci in the basal amygdaloid complex but not the frontal cortex. CONCLUSION: Kindled seizures of the basal amygdala induce hyperproliferation of bone marrow progenitor cells, suggesting that alterations in immunological functions observed following seizure activity may be due to changes in hematopoietic functions. Such changes appear to be site specific within the brain.

Effects of hemispheric lateralization and site specificity on immune alterations induced by kindled temporal lobe seizures.

The effects of kindled seizures elicited from sites in the left and right temporal lobes on mitogen-induced proliferation (LPS, Con A, PHA) and induction of representative TH1 (IFN-gamma) and TH2 (IL-10, IL-4) cytokines were determined in activated rat splenocytes. With reference to cell proliferation, the changes depended on the hemispheric side and location of kindling. Kindling of the left side mediated significant increase in cell proliferation by LPS. Left side kindling resulted in decreased cell proliferation by PHA. Although right side kindling showed no change when taken together, further analysis showed that the reduced proliferation by PHA was mediated when the pyriform cortex was kindled with no change from amygdaloid nuclei. Similar hemispheric polarization was observed in the production of IL-10 and IFN-gamma by Con A-stimulated splenocytes in left side kindled rats. Hence, kindled temporal lobe seizures induced changes in specific immune functions. These effects are not only lateralized but are also specific with respect to the particular region kindled. Since epileptic patients have altered immune functions, this report contributes to our understanding of this complex immune-brain cross-talk in epilepsy.