Biomedical subjects

Justin K Kane

Publications and source records attributed to Justin K Kane.

7 recordsLinked to original sources

PubMed2004

Time-dependent changes in transcriptional profiles within five rat brain regions in response to nicotine treatment.

Many years of behavioral and neurobiology studies have demonstrated broad physiological and pharmacological effects of nicotine on the central nervous system (CNS). However, the gene expression profiles associated with these effects are largely unknown. In this study, we characterized gene expression profiles in the prefrontal cortex, striatum, hypothalamus, amygdala and ventral tegmental area of the rat brain in response to subacute and chronic systemic nicotine administration using a pathway-focused microarray developed in this laboratory that contains 638 sequence-verified genes representing broad, yet targeted, biological functions. By comparing the regional effects of nicotine treatment on gene expression levels, we derived the expression profiles of targeted genes and gene families responding to the new environment created by nicotine throughout the complex connections of the CNS. While the expression of many genes was modulated by nicotine in several regions, only a few were co-modulated in multiple brain regions, suggesting region-specific transcriptional responses. Cluster analysis of significantly altered genes within each brain region over the course of nicotine treatment indicated the genes could be grouped into clusters. Subsequent ANOVA analysis demonstrated these clusters within each brain region to be significantly different at most time points. The clusters were comprised of broad functional groups, such as signaling, neurotransmission and protein modifications, demonstrating unique expression patterns within each region. Using a systematic approach to compare the different regional responses to nicotine administration will eventually provide a better understanding of how the different brain regions responding to this drug.

Amygdala↗

PubMed2004

Nicotine coregulates multiple pathways involved in protein modification/degradation in rat brain.

Previously, we used cDNA microarrays to demonstrate that the phosphatidylinositol and MAP kinase signaling pathways are regulated by nicotine in different rat brain regions. In the present report, we show that, after exposure to nicotine for 14 days, ubiquitin, ubiquitin-conjugating enzymes, 20S and 19S proteasomal subunits, and chaperonin-containing TCP-1 protein (CCT) complex members are upregulated in rat prefrontal cortex (PFC) while being downregulated in the medial basal hypothalamus (MBH). In particular, relative to saline controls, ubiquitins B and C were upregulated by 33% and 47% (P<0.01), respectively, in the PFC. The proteasome beta subunit 1 (PSMB1) and 26S ATPase 3 (PSMC3) genes were upregulated in the PFC by 95% and 119% (P<0.001), respectively. In addition to the protein degradation pathway of the ubiquitin-proteasome complexes, we observed in the PFC an increase in the expression of small, ubiquitin-related modifiers (SUMO) 1 and 2 by 80% and 33%, respectively (P<0.001), and in 3 of 6 CCT subunits by up to 150% (P<0.0001). To a lesser extent, a change in the opposite direction was obtained in the expression of the same gene families in the MBH. Quantitative real-time RT-PCR was used to validate the microarray results obtained with some representative genes involved in these pathways. Taken together, our results suggest that, in response to systemic nicotine administration, the ubiquitin-proteasome, SUMO, and chaperonin complexes provide an intricate control mechanism to maintain cellular homeostasis, possibly by regulating the composition and signaling of target neurons in a region-specific manner.

Animals↗

PubMed2004

Internalization of neuropeptide Y Y1 and Y5 and of pancreatic polypeptide Y4 receptors is inhibited by lithium in preference to sodium and potassium ions.

The receptor-linked internalization of [125I] human neuropeptide Y (NPY) in Chinese hamster ovary (CHO) cells expressing the guinea-pig Y1 receptors or in human endometrial carcinoma-1B (Hec-1B) cells expressing the human Y5 receptor, as well as the receptor-linked internalization of human pancreatic polypeptide (hPP) receptor expressed in CHO cells, is selectively inhibited by low molarities of the Li+ cation. The Na+ and K+ cations decreased the receptor-linked internalization of agonist peptides only at high molar inputs, and largely in proportion to the reduction of cell surface binding of Y ligand peptides, dependent on ion concentration and the type of Y receptor examined. With particulates isolated from disrupted cells, there was no preferential inhibition by Li+ relative to Na+ in the binding of type-specific ligand peptides to Y receptors of any type. The observed difference could be connected to the known ability of Li+ to modify active conformations of signal transducers, which may also directly or indirectly affect the internalization motors. The decrease in the rate of Y receptor internalization by Li+ also points to a possible alteration of Y receptor signaling in vivo by lithium at acute therapeutically employed dose levels.

Animals↗

PubMed2003

Effect of nicotine on the expression of leptin and forebrain leptin receptors in the rat.

We have previously reported that chronic nicotine administration (4.0 mg/kg/day by i.p. injection over 14 days) up-regulates orexin/hypocretin and neuropeptide Y (NPY) mRNA expression and peptide levels within the hypothalamus. Since there exists a coregulation between these neuropeptides and the protein leptin, the present study was undertaken to determine whether nicotine has a regulatory effect on leptin signaling. Under the same experimental regimen used previously, we found that nicotine down-regulates plasma leptin concentration by 48.8% (P<0.001) and leptin RNA level by 11.4% and 12.4%, respectively, in the perirenal and epididymal white adipose tissue (PWAT, EWAT) compared to the saline controls. We also measured an approximately 20% decrease in white and brown adipose tissue (BAT) by weight in nicotine-treated animals relative to saline controls (P<0.05). On the other hand, we found that chronic nicotine administration increased the expression levels of OB-Rb mRNA by 12% and OB-R mRNA by 25% in the medial basal hypothalamus compared to control rats. Subsequent radioligand binding assays indicated that nicotine also significantly increased leptin binding in ventromedial hypothalamic area (VMA), medial basal hypothalamic area (MBA), arcuate nucleus/median eminence, paraventricular nuclei and piriform cortex. Taken together, our results revealed that nicotine is involved in the regulation of leptin signaling, suggesting that leptin and its receptor play a role in the anorectic effects of nicotine on food intake and body weight in rats.

Adipose Tissue↗

PubMed2003

Nicotine, body weight and potential implications in the treatment of obesity.

Obesity is an epidemic problem in the U. S. and many other industrialized nations. Historically, the drugs used for the treatment of obesity generally targeted small molecule neurotransmitters. As research grows to decipher the underlying molecular mechanisms behind energy homeostasis, it is becoming evident that the modulating effects of neuropeptides also are critical in the regulation of appetite and metabolism. The search for drugs to modify these monoaminergic and peptidergic pathways may eventually prove successful in the treatment of obesity. While tobacco smoking has long been used as one strategy to maintain a lower body weight, especially in female smokers, its adverse associations with addiction and disease overshadow its potential use as an antiobesity agent. Potential pharmacological effects of nicotine could be better understood as the intricacies of the nicotinic acetylcholine receptor are revealed. The objective of this review is threefold: first is to provide an overview of the physiological effects of nicotine on body weight while focusing on the drugs that are available as antiobesity and smoking cessation agents. Second is to provide the present status of the nicotinic acetylcholine receptor as it relates to energy homeostasis and its potential as an effective treatment modality for obesity. Third is to present the current knowledge with respect to nicotine's effects on energy homeostatic and reward related pathways at the molecular level. A better understanding of the regulatory mechanisms underlying the pharmacological effects of nicotine on body weight will provide insights in identification of potential targets for the development of appropriate medicines in the treatment of obesity.

Animals↗

PubMed2002

A pool of Y2 neuropeptide Y receptors activated by modifiers of membrane sulfhydryl or cholesterol balance.

The cloned guinea-pig Y2 neuropeptide Y (NPY) receptors expressed in Chinese hamster ovary (CHO) cells, as well as the Y2 receptors natively expressed in rat forebrain, are distributed in two populations. A smaller population that is readily accessed by agonist peptides on the surface of intact cells constitutes less than 30% of Y2 receptors detected in particulates after cell homogenization. A much larger fraction of cell surface Y2 sites can be activated by sulfhydryl modifiers. A fast and large activation of these masked or cryptic sites could be obtained with membrane-permeating, vicinal cysteine-bridging arsenical phenylarsine oxide. A lower activation is effected by N-ethylmaleimide, an alkylator that slowly penetrates lipid bilayers. The restricted-access alkylator, 2-[(trimethylammonium)ethyl]methanethiosulfonate, was not effective in unmasking these sites. Some of the hidden cell surface Y2 sites could be activated by polyene filipin III through complexing of membrane cholesterol. The results are consistent with the presence of a large Y2 reserve in a compartment that can be accessed by alteration of sulfhydryl balance or fluidity of the cell membrane, and by treatments that affect the anchoring and aggregation of membrane proteins.

Animals↗

PubMed2002

Microarray technology and its application on nicotine research.

Since its development, microarray technique has revolutionized almost all fields of biomedical research by enabling high-throughput gene expression profiling. Using cDNA microarrays, thousands of genes from various organisms have been examined with respect to differentiation/development, disease diagnosis, and drug discovery Nevertheless, research on nicotine using cDNA microarrays has been rather limited. Therefore, it is our intention in this article to report the findings of our cDNA microarray study on nicotine. We first present an overview of the microarray technology, particularly focusing on the factors related to microarray design and analysis. Second, we provide a detailed description of several newly identified biological pathways in our laboratory, such as phosphatidylinositol signaling and calcium homeostasis, which are involved in response to chronic nicotine administration. Additionally, we illustrate how comparisons between microarray studies help identify candidate genes that potentially may explain the observed inverse association between smoking and schizophrenia. Lastly, given the early stage of microarray research on nicotine, we elaborate on the need for an efficient analysis of genetic networks to further enhance our understanding of the mechanisms involved in nicotine abuse and addiction.

Animals↗