Background Fetal alcohol spectrum disorders (FASD) result from fetal exposure to alcohol and are the leading cause of mental retardation in the United States. There is currently no effective treatment that targets the causes of these disorders. Thus, novel therapies are critically needed to limit the neurodevelopmental and neurodegenerative pathologies associated with FASD. Methods A neonatal mouse FASD model was used to examine the role of the neuroimmune system in ethanol-induced neuropathology. Neonatal C57BL/6 mice were treated with ethanol, with or without pioglitazone, on postnatal days 4 through 9 and tissue was harvested one day post-treatment. Pioglitazone is a peroxisome proliferator-activated receptor (PPAR)-γ agonist that exhibits anti-inflammatory activity and is neuroprotective. We compared the effects of ethanol with or without pioglitazone on cytokine and chemokine expression and microglial morphology in the hippocampus, cerebellum, and cerebral cortex. Results In ethanol-treated animals compared to controls, cytokines IL-1β and TNF-α mRNA levels were increased significantly in the hippocampus, cerebellum, and cerebral cortex. Chemokine CCL2 mRNA was increased significantly in the hippocampus and cerebellum. Pioglitazone effectively blocked the ethanol-induced increase in the cytokines and chemokine in all tissues to the level expressed in handled-only and vehicle-treated control animals. Ethanol also produced a change in microglial morphology in all brain regions that was indicative of microglial activation, and pioglitazone blocked this ethanol-induced morphological change. Conclusions These studies indicate that ethanol activates microglia to a pro-inflammatory stage and also increases the expression of neuroinflammatory cytokines and chemokines in diverse regions of the developing brain. Further, the anti-inflammatory and neuroprotective PPAR-γ agonist pioglitazone blocked these effects. It is proposed that microglial activation and inflammatory molecules expressed as a result of ethanol treatment during brain development contribute to the sequelae associated with FASD. Thus, pioglitazone, and anti-inflammatory pharmaceuticals more broadly, have potential as novel therapeutics for FASD.

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The initial discovery thatob/obmice become obese because of a recessive mutation of the leptin gene has been crucial to discover the melanocortin pathway to control appetite. In the melanocortin pathway, the fed state is signaled by abundance of circulating hormones such as leptin and insulin, which bind to receptors expressed at the surface of pro-opiomelanocortin (POMC) neurons to promote processing of POMC to the mature hormone α-melanocyte-stimulating hormone (α-MSH). The α-MSH released by POMC neurons then signals to decrease energy intake by binding to melanocortin-4 receptor (MC4R) expressed by MC4R neurons to the paraventricular nucleus (PVN). Conversely, in the ‘starved state’ activity of agouti-related neuropeptide (AgRP) and of neuropeptide Y (NPY)-expressing neurons is increased by decreased levels of circulating leptin and insulin and by the orexigenic hormone ghrelin to promote food intake. This initial understanding of the melanocortin pathway has recently been implemented by the description of the complex neuronal circuit that controls the activity of POMC, AgRP/NPY and MC4R neurons and downstream signaling by these neurons. This review summarizes the progress done on the melanocortin pathway and describes how obesity alters this pathway to disrupt energy homeostasis. We also describe progress on how leptin and insulin receptors signal in POMC neurons, how MC4R signals and how altered expression and traffic of MC4R change the acute signaling and desensitization properties of the receptor. We also describe how the discovery of the melanocortin pathway has led to the use of melanocortin agonists to treat obesity derived from genetic disorders.

Seizures are the manifestation of highly synchronized burst firing of a large population of cortical neurons. Epileptiform bursts with an underlying plateau potential in neurons are a cellular correlate of seizures. Emerging evidence suggests that the plateau potential is mediated by neuronal canonical transient receptor potential (TRPC) channels composed of members of the TRPC1/4/5 subgroup. We previously showed that TRPC1/4 double-knockout (DKO) mice lack epileptiform bursting in lateral septal neurons and exhibit reduced seizure-induced neuronal cell death, but surprisingly have unaltered pilocarpine-induced seizures. Here, we report that TRPC5 knockout (KO) mice exhibit both significantly reduced seizures and minimal seizure-induced neuronal cell death in the hippocampus. Interestingly, epileptiform bursting induced by agonists for metabotropic glutamate receptors in the hippocampal CA1 area is unaltered in TRPC5 KO mice, but is abolished in TRPC1 KO and TRPC1/4 DKO mice. In contrast, long-term potentiation is greatly reduced in TRPC5 KO mice, but is normal in TRPC1 KO and TRPC1/4 DKO mice. The distinct changes from these knockouts suggest that TRPC5 and TRPC1/4 contribute to seizure and excitotoxicity by distinct cellular mechanisms. Furthermore, the reduced seizure and excitotoxicity and normal spatial learning exhibited in TRPC5 KO mice suggest that TRPC5 is a promising novel molecular target for new therapy.

Canonical transient receptor potential channels (TRPCs) are receptor-operated cation channels that are activated in response to phospholipase C signaling. Although TRPC1 is ubiquitously expressed in the brain, TRPC4 expression is the most restrictive, with the highest expression level limited to the lateral septum. The subunit composition of neuronal TRPC channels remains uncertain because of conflicting data from recombinant expression systems. Here we report that the large depolarizing plateau potential that underlies the epileptiform burst firing induced by metabotropic glutamate receptor agonists in lateral septal neurons was completely abolished in TRPC1/4 double-knockout mice, and was abolished in 74% of lateral septal neurons in TRPC1 knockout mice. Furthermore, neuronal cell death in the lateral septum and the cornu ammonis 1 region of hippocampus after pilocarpine-induced severe seizures was significantly ameliorated in TRPC1/4 double-knockout mice. Our data suggest that both TRPC1 and TRPC4 are essential for an intrinsic membrane conductance mediating the plateau potential in lateral septal neurons, possibly as heteromeric channels. Moreover, excitotoxic neuronal cell death, an underlying process for many neurological diseases, is not mediated merely by ionotropic glutamate receptors but also by heteromeric TRPC channels activated by metabotropic glutamate receptors. TRPC channels could be an unsuspected but critical molecular target for clinical intervention for excitotoxicity.

Background Alcohol use occurs across the lifespan beginning in adolescence and continuing through adulthood. Ethanol-induced pathology varies with age and includes changes in neurogenesis, neurodegeneration, and glial cell activation. Ethanol-induced changes in glial activation and immune activity are believed to contribute to ethanol-induced neuropathology. Recent studies indicate an emerging role of glial-derived neuroimmune molecules in alcohol abuse and addiction. Methods Adolescent and adult C57BL/6 mice were treated via gavage with 6 g/kg ethanol for 10 days and tissue was harvested one day post-treatment. We compared the effects of ethanol on chemokine and cytokine expression and astrocyte GFAP immunostaining and morphology in the hippocampus, cerebellum, and cerebral cortex. Results Ethanol increased mRNA levels of the chemokine CCL2/MCP-1 in all three regions of adult mice relative to controls. The cytokine IL-6 was selectively increased only in the adult cerebellum. Ethanol did not affect mRNA levels of the cytokine TNF-α in any of these brain regions in adult animals. Interestingly, CCL2, IL-6, and TNF-α mRNA levels were not increased in the hippocampus, cerebellum, or cortex of adolescent mice. Ethanol treatment of adult and adolescent mice resulted in increased GFAP immunostaining. Conclusions Collectively, these data indicate an age- and region-specific susceptibility to ethanol regulation of neuroinflammatory and addiction-related molecules as well as astrocyte phenotype. These studies may have important implications concerning differential alcohol-induced neuropathology and alcohol addiction across the lifespan.

Pilocarpine-induced status epilepticus (SE) is a widely used seizure model in mice, and the Racine scale has been used to index seizure intensity. The goal of this study was to analyze electroencephalogram (EEG) quantitatively using fast Fourier transformation (FFT) and statistically evaluate the correlation of electrographic seizures with convulsive behaviors. Simultaneous EEG and video recordings in male mice in a mixed genetic background were conducted and pilocarpine was administered intraperitoneally to induce seizures. The videos were graded using the Racine scale and the root-mean-square (RMS) power analysis of EEG was performed with Sirenia Seizure Pro software. We found that the RMS power was very weakly correlated with convulsive behavior induced by pilocarpine. Convulsive behaviors appeared long before electrographic seizures and showed a strong negative correlation with theta frequency activity and a moderate positive correlation with gamma frequency activity. Racine scores showed moderate correlations with RMS power across multiple frequency bands during the transition from first electrographic seizure to SE. However, there was no correlation between Racine scores and RMS power during the SE phase except a weak correlation with RMS power in the theta frequency. Our analysis reveals limitations of the Racine scale as a primary index of seizure intensity in status epilepticus, and demonstrates a need for quantitative analysis of EEG for an accurate assessment of seizure onset and severity.

Utilizing cyto-, myelo-, and chemoarchitecture as well as connectional criteria, the present study reveals the interstitial system of the spinal trigeminal tract (InSy-SVT) in the rat to be composed of five morphologically and functionally distinct components that are distributed within spatially restricted regions of the lateral medulla. The first component is represented by scattered interstitial cells and neuropil, which extend laterally into SVT from the superficial laminae of the medullary dorsal horn (MDH). The second component, the dorsal paramarginal nucleus (PaMd), consists of a small group of marginal (lamina I)-like neurons and neuropil situated within the dorsolateral part of SVT at the rostral pole of MDH. The third component represents a trigeminal extension of the parvocellular reticular formation (V-Rpc) into the ventromedial aspect of SVT at levels extending from rostral MDH to the caudal part of trigeminal nucleus interpolaris (Vi). The fourth component, the paratrigeminal nucleus (PaV), consists of a large accumulation of neurons and neuropil situated within the dorsal part of SVT throughout the caudal half of Vi. The fifth component is the insular trigeminal-cuneatus lateralis nucleus (iV-Cul), which is a discontinuous collection of neurons and neuropil interspersed among fibers of SVT as well as wedged between it and the spinocerebellar tract. Thalamic projection neurons are located in PaMd and V-Rpc, whereas cerebellar projecting neurons are confined to iV-Cul.