Double immunofluorescent evidence that oxidative stress-associated activation of JNK/AP-1 signaling participates in neuropeptide-mediated appetite control.

Amphetamine (AMPH), an appetite suppressant, alters expression levels of neuropeptide Y (NPY) and cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus. This study explored the potential role of cJun-N-terminal kinases (JNK) in appetite control, mediated by reactive oxygen species (ROS) and activator protein-1 (AP-1) in AMPH-treated rats. Rats were given AMPH daily for 4 days. Changes in feeding behavior and expression levels of hypothalamic NPY, CART, cFos, cJun, phosphorylated JNK (pJNK), as well as those of anti-oxidative enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GP) and glutathione S-transferase (GST), were examined and compared. Following AMPH treatment, food intake and NPY expression decreased, whereas the other proteins expression and AP-1/DNA binding activity increased. Both cerebral cJun inhibition and ROS inhibition attenuated AMPH anorexia and modified detected protein, revealing a crucial role for AP-1 and ROS in regulating AMPH-induced appetite control. Moreover, both pJNK/CART and SOD/CART activities detected by double immunofluorescent staining increased in hypothalamic arcuate nucleus in AMPH-treated rats. The results suggested that pJNK/AP-1 signaling and endogenous anti-oxidants participated in regulating NPY/CART-mediated appetite control in rats treated with AMPH. These findings advance understanding of the molecular mechanism underlying the role of pJNK/AP-1 and oxidative stress in NPY/CART-mediated appetite suppression in AMPH-treated rats.

Role of hypoxia-inducible factor-1α in regulating oxidative stress and hypothalamic neuropeptides-mediated appetite control.

Hypoxia-inducible factor 1 (HIF-1) is a transcriptional activator responding to hypoxia. Amphetamine (AMPH), however, can activate HIF-1 under normoxic conditions, which is associated with the co-activation of oxidative stress. Hypothalamic neuropeptides and anti-oxidative enzymes have been found to participate in amphetamine (AMPH)-mediated appetite control. The present study examined whether HIF-1 was involved in the oxidative stress and anorectic action of AMPH. Rats were daily treated with AMPH for 4 days, and expression levels of HIF-1α, superoxide dismutase (SOD), catalase, neuropeptide Y (NPY), proopiomelanocortin (POMC), phosphatidylinositol 3-kinase (PI3K), and nuclear factor-kappaB (NF-κB) were assessed and compared. Results revealed that feeding behavior and NPY decreased, whereas HIF-1α/DNA binding activity and SOD, POMC, PI3K, and NF-κB expression levels increased in AMPH-treated rats. Further experiment revealed that intracerebroventricular (i.c.v.) pretreatment with HIF-1α inhibitor modified feeding behavior and expression levels of hypothalamic protein assessed. Another experiment revealed that pretreatment (i.c.v.) with reactive oxygen species scavenger modulated HIF-1α, NPY, POMC, PI3K, and NF-κB expression levels in AMPH-treated rats. It is suggested that HIF-1α plays a functional role in the increase of oxidative stress and the modulation of NFκB/NPY/POMC-mediated appetite control in AMPH-treated rats. These findings advance the knowledge of HIF-1α in the regulation of central dopamine agonist-mediated appetite control.

Role of hypothalamic leptin-LepRb signaling in NPY-CART-mediated appetite suppression in amphetamine-treated rats.

Leptin is an adipose tissue hormone which plays an important role in regulating energy homeostasis. Amphetamine (AMPH) is a drug of appetite suppressant, which exerts its effect by decreasing the expression of hypothalamic neuropeptide Y (NPY) and increasing that of cocaine- and amphetamine-regulated transcript (CART). This study investigated whether leptin, the leptin receptor (LepRb) and the signal transducer and activator of transcription-3 (STAT3) were involved in NPY/CART-mediated appetite suppression in AMPH-treated rats. Rats were given AMPH daily for four days, and changes in the levels of blood leptin and hypothalamic NPY, CART, LepRb, Janus kinases 2 (JAK2), and STAT3 were assessed and compared. During the AMPH treatment, blood leptin levels and hypothalamic NPY expression decreased, with the largest reduction observed on Day 2. By contrast, the expression of hypothalamic CART, LepRb, JAK2, and STAT3 increased, with the maximum response on Day 2. Furthermore, the binding activity of pSTAT3/DNA increased and was expressed in similar pattern to that of CART, LepRb, and JAK2. An intracerebroventricular infusion of NPY antisense 60min prior to AMPH treatment increased the levels of leptin, as well as the expression in LepRb, JAK2, and CART, whereas an infusion of STAT3 antisense decreased these levels and the expression of these parameters. The results suggest that blood leptin and hypothalamic LepRb-JAK2-STAT3 signaling involved in NPY-CART-regulated appetite suppression in AMPH-treated rats. The findings may aid understanding the role of leptin-LepRb during the treatment of anorectic drugs.

Knockdown of the transcript of ERK in the brain modulates hypothalamic neuropeptide-mediated appetite control in amphetamine-treated rats.

BACKGROUND AND PURPOSE: Amphetamine is a releaser of dopamine stored in synaptic terminals, which can suppress appetite by changing the expression levels of neuropeptide Y (NPY) and proopiomelanocortin (POMC) in the hypothalamus. This study explored whether ERKs are involved in appetite control mediated by cAMP response element binding protein (CREB), NPY and POMC in amphetamine-treated rats. EXPERIMENTAL APPROACH: Rats were given amphetamine for 4 days, and changes in feeding behaviour and expression levels of phosphorylated-ERK (pERK), pCREB, NPY and melanocortin MC3 receptors were examined and compared. KEY RESULTS: Following amphetamine treatment, food intake, body weight and NPY expression decreased, whereas the expression of pERK, pCREB, MC3 receptors and pCREB/DNA binding activity increased. In amphetamine-treated rats, both cerebral ERK knockdown and pretreatment with a peripheral dopamine receptor antagonist decreased NPY but increased pERK, pCREB and MC3 receptor expression. Moreover, the immunofluorescence of hypothalamic pERK increased following amphetamine treatment. CONCLUSIONS AND IMPLICATIONS: These results suggest that ERK/CREB signalling participates in the effects mediated by dopamine receptor/NPY/POMC on appetite control in rats treated with amphetamine. These findings advance the knowledge on the involvement of ERK/CREB signalling in the reciprocal regulation by NPY and POMC of appetite after amphetamine treatment.

Participation of ghrelin signalling in the reciprocal regulation of hypothalamic NPY/POMC-mediated appetite control in amphetamine-treated rats.

Hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC) have been documented to participate in amphetamine (AMPH)-induced appetite suppression. This study investigated whether ghrelin signalling is associated with changes in NPY/POMC-mediated appetite control. Rats were given AMPH daily for four days, and changes in food intake, body weight, plasma ghrelin, hypothalamic NPY, melanocortin 3 receptor (MC3R), ghrelin O-acyltransferase (GOAT), acyl ghrelin (AG) and ghrelin receptor (GHSR1a) were examined and compared. Food intake, body weight and NPY expression decreased, while MC3R expression increased and expressed reciprocally to NPY expression during AMPH treatment. Plasma ghrelin and hypothalamic AG/GOAT/GHSR1a expression decreased on Day 1 and Day 2, which was associated with the positive energy metabolism, and returned to normal levels on Day 3 and Day 4, which was associated with the negative energy metabolism; this expression pattern was similar to that of NPY. Infusion with a GHSR1a antagonist or an NPY antisense into the brain enhanced the decrease in NPY and AG/GOAT/GHSR1a expression and the increase in MC3R expression compared to the AMPH-treated group. Peripheral ghrelin and the central ghrelin system participated in the regulation in AMPH-induced appetite control. These results shed light on the involvement of ghrelin signalling in reciprocal regulation of NPY/POMC-mediated appetite control and may prove useful for the development of anti-obesity drugs.

Role of oxidative stress in disrupting the function of negative glucocorticoid response element in daily amphetamine-treated rats.

Amphetamine (AMPH)-induced appetite suppression is associated with changes in hypothalamic reactive oxygen species (ROS), antioxidants, neuropeptides, and plasma glucocorticoid. This study explored whether ROS and glucocorticoid response element (GRE), which is the promoter site of corticotropin-releasing hormone (CRH) gene, participated in neuropeptides-mediated appetite control. Rats were treated daily with AMPH for four days, and changes in food intake, plasma glucocorticoid and expression levels of hypothalamic neuropeptide Y (NPY), proopiomelanocortin (POMC), superoxide dismutase (SOD), CRH, and glucocorticoid receptor (GR) were examined and compared. Results showed that food intake decreased and NPY gene down-regulated, while POMC, SOD, and CRH gene up-regulated during AMPH treatment. GR and GRE-DNA bindings were disrupted on Day 1 and Day 2 when glucocorticoid levels were still high. Pretreatment with GR inhibitor or ROS scavenger modulated mRNA levels in NPY, POMC, SOD and CRH in AMPH-treated rats. We suggest that disruptions of negative GRE (nGRE) on Day 1 and Day 2 are associated with an increase in oxidative stress during the regulation of NPY/POMC-mediated appetite control in AMPH-treated rats. These results advance the understanding of molecular mechanism in regulating AMPH-mediated appetite suppression.

Growth Modulation of Diabetic Factors and Antidiabetic Drugs on Prostate Cancer Cell Lines.

Risk factors for prostate cancer (PCa) include age, hormones, race, family history and diet. Recently, epidemiologic evidence has indicated that history of diabetes mellitus (DM) is inversely associated with risk of PCa. However, epidemiological investigations have yielded inconsistent results. Hence, the exact mechanism of DM-induced reduction in the incidence of PCa has yet to be fully elucidated. The aim of this study was to investigate the effects of DM factors, including glucose, insulin and insulin-like growth factor-1 (IGF-1), on the proliferation of PCa cell lines in vitro. Cell proliferation and expression of hormone receptors was examined in MTT assay and Western blot analysis, respectively. The results showed that DM factors did not affect the viability of androgen receptor (AR)-expressing PCa cell lines. However, cell proliferation increased after treatment with DM factors in androgen-independent PCa cell lines. On PCa tissue arrays, intensities of total AR and nuclear IGF-1R were higher in malignant tissues than in normal prostate glands. In terms of hormonal receptors, androgen-dependent LNCaP cells treated with insulin and IGF-1 in a low-serum medium showed decreased expression of insulin receptor beta (IRß) and elevated expression of IGF-1 receptor beta (IGF-1Rß). Moreover, expression of AR was upregulated after insulin and IGF-1 treatment in LNCaP cells, but not in the other PCa cell lines. Most of the studied antidiabetic drugs promoted the viability of PCa cells. However, metformin decreased the viability of AR-expressing PCa cells. These results suggest that diabetic factors modify the expression of AR, IR and IGF-1R to increase cancer cell proliferation. Moreover, the growth suppressing effects of metformin on PCa may be via the regulation of the AR signaling pathway.

Involvement of oxidative stress in the regulation of NPY/CART-mediated appetite control in amphetamine-treated rats.

Amphetamine (AMPH) treatment can suppress appetite and increase oxidative stress in the brain. AMPH-induced appetite suppression is associated with the regulation of neuropeptide Y (NPY) and cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus. The present study explored whether antioxidants, including glutathione S-transferase (GST) and glutathione peroxidase (GP), were involved in this NPY/CART-mediated appetite control. Rats were treated daily with AMPH for four days. Changes in food intake and expression levels of hypothalamic NPY, CART, GST, and GP were examined and compared. Results showed that, in AMPH-treated rats, (1) food intake and NPY expression decreased, while CART, GST, and GP expression increased; (2) NPY knockdown in the brain enhanced the decrease in NPY and the increases in CART, GST, and GP expression; and (3) central inhibition of reactive oxygen species production decreased GST and GP and modulated AMPH anorexia and the expression levels of NPY and CART. The present results suggest that oxidative stress in the brain participates in regulating NPY/CART-mediated appetite control in AMPH-treated rats. These results may advance the knowledge regarding the molecular mechanism of AMPH-evoked or NPY/CART-mediated appetite suppression.

Both neuropeptide Y knockdown and Y1 receptor inhibition modulate CART-mediated appetite control.

Amphetamine (AMPH)-induced appetite suppression has been attributed to its inhibition of neuropeptide Y (NPY)-containing neurons in the hypothalamus. This study examined whether hypothalamic cocaine- and amphetamine-regulated transcript (CART)-containing neurons and NPY Y1 receptor (Y1R) were involved in the action of AMPH. Rats were treated daily with AMPH for four days, and changes in feeding behavior and expression levels of NPY, CART, and POMC were assessed and compared. The results showed that both feeding behavior and NPY expression decreased during AMPH treatment, with the biggest reduction occurring on Day 2. By contrast, the expression of CART and melanocortin 3 receptor (MC3R), a member of the POMC neurotransmission, increased with the maximum response on Day 2, directly opposite to the NPY expression results. The intracerebroventricular infusion of NPY antisense or Y1R inhibitor both modulated AMPH-induced anorexia and the expression levels of MC3R and CART. The results suggest that in the hypothalamus both POMC- and CART-containing neurons participate in regulating NPY-mediated appetite control during AMPH treatment. These results may advance the knowledge of molecular mechanism of anorectic drugs.

Targeting oxidative stress in the hypothalamus: the effect of transcription factor STAT3 knockdown on endogenous antioxidants-mediated appetite control.

It has been reported that the redox sensing system in the hypothalamus participates in fuel metabolism and that endogenous antioxidants contribute to the regulation of phenylpropanolamine (PPA), an anorectic drug-induced appetite suppression. We explored whether the signal transducer and activator of transcription-3 (STAT3) is involved in PPA's action. Rats were given PPA once a day for 4 days. Changes in endogenous antioxidants, Janus kinase-2 (JAK2), STAT3, neuropeptide Y (NPY), and proopiomelanocortin (POMC), levels during PPA treatment were assessed and compared. Feeding, body weight, and NPY decreased with the biggest reduction on Day 2 during PPA treatment. Antioxidants, JAK2, pSTAT3, POMC expression, and STAT3/DNA-binding activity increased and were expressed in a pattern opposite to NPY expression. Moreover, cerebral STAT3 knockdown modified PPA-induced anorexia and antioxidants, POMC, and NPY expression. superoxide dismutase immunoreactivity in the hypothalamus increased and the inhibition of hypothalamic reactive oxygen species (ROS) production reversed antioxidants, STAT3, POMC, and NPY expression. It is suggested that hypothalamic JAK2-STAT3 participates in regulating antioxidants-mediated appetite control. This result may further the understanding of ROS-involved appetite control.

Inhibition of the invasion and migration of renal carcinoma 786­o­si3 cells in vitro and in vivo by Koelreuteria formosana extract.

Koelreuteria formosana ethanolic extract (KFEE) is obtained from natural plants that are endemic to Taiwan. In a previous study, it was demonstrated that KFEE inhibited low-density lipoprotein (LDL) and prevented oxidized LDL­induced apoptosis in endothelial cells. In the present study, KFEE was shown to inhibit the invasion and migration of 786­O­SI3 renal cell carcinoma (RCC) cells while not exhibiting any cytotoxic effects. 786­O­SI3 cells were treated with KFEE at numerous concentrations of ≤100 µg/ml for 24 h. In order to examine the effects of KFEE, cells were then subjected to a series of assays for cell viability (MTT), wound healing migration, cell invasion and migration, gelatin zymography, casein zymography and immunofluorescence, as well as western blot analysis. KFEE was shown to decrease levels of matrix metalloproteinase­2, phosphorylated (p­)focal adhesion kinase Try925, p­paxillin Ser178, p­mitogen­activated protein kinase kinase 1/2, p­myosin light chain and p­extracellular signal-regulated kinase 1/2 in 786-0-SI3 cells. Reduction of lung metastases was observed in KFEE-treated mice compared with vehicle­treated control mice. KFEE inhibited the invasion of RCC cells and may have the potential for use as a chemopreventive agent against RCC metastasis.

Involvement of hypothalamic PI3K-STAT3 signalling in regulating appetite suppression mediated by amphetamine.

BACKGROUND AND PURPOSE: Appetite suppression induced by amphetamine has been attributed to its inhibition of neuropeptide Y (NPY) neurons and activation of pro-opiomelanocortin (POMC) neurons in the hypothalamus. This study examined whether STAT3 was involved in these actions of amphetamine. EXPERIMENTAL APPROACH: Rats were given amphetamine daily for 4 days. Changes in the expression of NPY, POMC, melanocortin MC3 receptors, PI3K and STAT3 in the hypothalamus were assessed by RT-PCR and Western blotting. Antisense oligonucleotides to STAT3 were also used. KEY RESULTS: Expression of NPY decreased with a maximum effect day 2 of amphetamine treatment. Expression of POMC, MC3 receptors, PI3K and STAT3 increased with a maximum response on day 2. Moreover, phosphorylation of STAT3 and its DNA binding activity increased and was expressed in a similar pattern. Infusion (i.c.v.) of STAT3 antisense at 60 min before amphetamine treatment, partly blocked amphetamine-induced anorexia and modulated expression of NPY, POMC, MC3 receptors and PI3K, indicating the involvement of STAT3 in amphetamine-treated rats. CONCLUSIONS AND IMPLICATIONS: Hypothalamic PI3K-STAT3 signalling participated in the regulation of NPY- and POMC-mediated appetite suppression. These findings may contribute to a better understanding of anorectic drugs.

The neuropeptide Y Y1 receptor knockdown modulates activator protein 1-involved feeding behavior in amphetamine-treated rats.

BACKGROUND: Hypothalamic neuropeptide Y (NPY) and two immediate early genes, c-fos and c-jun, have been found to be involved in regulating the appetite-suppressing effect of amphetamine (AMPH). The present study investigated whether cerebral catecholamine (CA) might regulate NPY and POMC expression and whether NPY Y1 receptor (Y1R) participated in activator protein-1 (AP-1)-mediated feeding. METHODS: Rats were given AMPH daily for 4 days. Changes in the expression of NPY, Y1R, c-Fos, c-Jun, and AP-1 were assessed and compared. RESULTS: Decreased CA could modulate NPY and melanocortin receptor 4 (MC4R) expressions. NPY and food intake decreased the most on Day 2, but Y1R, c-Fos, and c-Jun increased by approximately 350%, 280%, and 300%, respectively, on Day 2. Similarly, AP-1/DNA binding activity was increased by about 180% on Day 2. The expression patterns in Y1R, c-Fos, c-Jun, and AP-1/DNA binding were opposite to those in NPY during AMPH treatment. Y1R knockdown was found to modulate the opposite regulation between NPY and AP-1, revealing an involvement of Y1R in regulating NPY/AP-1-mediated feeding. CONCLUSIONS: These results point to a molecular mechanism of CA/NPY/Y1R/AP-1 signaling in the control of AMPH-mediated anorexia and may advance the medical research of anorectic and anti-obesity drugs.

Inhibiting neuropeptide Y Y1 receptor modulates melanocortin receptor- and NF-κB-mediated feeding behavior in phenylpropanolamine-treated rats.

Neuropeptide Y (NPY) and nuclear factor-kappa B (NF-κB) are involved in regulating anorexia elicited by phenylpropanolamine (PPA), a sympathomimetic drug. This study explored whether NPY Y1 receptor (Y1R) is involved in this process, and a potential role for the proopiomelanocortin system was identified. Rats were given PPA once a day for 4days. Changes in the hypothalamic expression of the NPY, Y1R, NF-κB, and melanocortin receptor 4 (MC4R) levels were assessed and compared. The results indicated that food intake and NPY expression decreased, with the largest reductions observed on Day 2 (approximately 50% and 45%, respectively), whereas NF-κB, MC4R, and Y1R increased, achieving maximums on Day 2 (160%, 200%, and 280%, respectively). To determine the role of Y1R, rats were pretreated with Y1R antisense or a Y1R antagonist via intracerebroventricular injection 1h before the daily PPA dose. Y1R knockdown and inhibition reduced PPA anorexia and partially restored the normal expression of NPY, MC4R, and NF-κB. The data suggest that hypothalamic Y1R participates in the appetite-suppression from PPA by regulating MC4R and NF-κB. The results of this study increase our understanding of the molecular mechanisms in PPA-induced anorexia.

The identification of neuropeptide Y receptor subtype involved in phenylpropanolamine-induced increase in oxidative stress and appetite suppression.

Hypothalamic neuropeptide Y (NPY) and superoxide dismutase (SOD) have been reported to participate in the regulation of appetite-suppressing effect of phenylpropanolamine (PPA), a sympathomimetic agent. This study explored whether Y1 receptor (Y1R) and/or Y5 receptor (Y5R) was involved in this regulation. Wistar rats were treated with PPA for 24 h. Changes in food intake and hypothalamic NPY, Y1R, Y5R, and SOD contents were assessed and compared. Results showed that food intake and NPY contents were decreased following PPA treatment, while Y1R and SOD contents were increased and Y5R contents remained unchanged. Moreover, although Y1R or Y5R knockdown by themselves could modify the food intake, Y1R but not Y5R knockdown could modify PPA-induced anorexia as well as NPY and SOD contents. In addition, selective inhibition of Y1R but not Y5R could modulate PPA-induced anorexia. It is suggested that Y1R but not Y5R participates in the anorectic response of PPA via the modulation of NPY and SOD. Results provide molecular mechanism of NPY-mediated PPA anorexia and may aid the understanding of the toxicology of PPA.

Neuropeptide Y Y1 receptor knockdown can modify glutathione peroxidase and c-AMP response element-binding protein in phenylpropanolamine-treated rats.

It has been reported that antioxidative enzymes, neuropeptide Y (NPY), and c-AMP response element-binding protein (CREB) are involved in regulating phenylpropanolamine (PPA)-mediated appetite suppression. Here, we investigated whether Y1 receptor (Y1R) might be involved in this regulation. Rats were daily treated with PPA for 4 days. Changes in the contents of NPY, Y1R, glutathione peroxidase (GP), and CREB were assessed and compared. Results showed that Y1R, GP, and CREB increased, with a maximal increase about 100, 200, and 150 %, respectively, on Day 2. By contrast, NPY decreased with a biggest reduction about 48 % on Day 2 and the pattern of expression during PPA treatment was opposite to those of Y1R, GP, and CREB. Central knockdown (using antisense) or inhibition (using antagonist) of Y1R expression modulated the anorectic response of PPA and the reciprocal regulation between NPY and GP (or CREB), revealing an essential role of Y1R in regulating NPY, GP, and CREB. These results suggest that Y1R participates in the reciprocal regulation of NPY, GP, and CREB in the hypothalamus during PPA treatment in conscious rats. The present results may aid the therapeutic research of PPA and related antiobesity drugs.

Involvement of neuropeptide Y Y1 receptor in the regulation of amphetamine-mediated appetite suppression.

Recently, we reported that an initial decrease followed by recovery of food intake was observed during four days of amphetamine (AMPH) treatment and suggested that these changes in response were mediated by changes in neuropeptide Y (NPY) and proopiomelanocortin (POMC). Here we investigated if Y1 receptor (Y1R) and/or Y5 receptor (Y5R) might be involved in this regulation. Rats were treated daily with AMPH for four days. Changes in the expression levels of Y1R, Y5R, melanocortin receptor 3 (MC3R), and NPY were assessed and compared. Results showed that Y1R and MC3R increased, with a maximal increase of about 210% on Day 2 but with a restoration to the normal level on Day 4. In contrast, NPY decreased with a biggest reduction of about 45% on Day 2 and the pattern of expression during AMPH treatment was opposite to those of Y1R and MC3R, while the expression of Y5R was not changed. Central inhibitions of NPY formation or Y1R activity modulated the anorectic response of AMPH and the reciprocal regulation of NPY and MC3R, revealing a crucial role of Y1R in this action. It is suggested that Y1R participates in the reciprocal regulation of NPY- and MC3R-containing neurons in the hypothalamus during the anorectic effect of AMPH. These results may further the understanding of Y1R in the control of eating.

NF-κB knockdown can modulate amphetamine-mediated feeding response.

This study determined if transcription factor NF-κB is involved in the effect of amphetamine (AMPH)-mediated feeding response. Moreover, possible roles of hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC) were also investigated. AMPH was administered daily to rats for four days. Changes in NF-κB, NPY and POMC expression were assessed and compared. The NPY gene was down-regulated with maximal response on Day 2 during AMPH treatment, which was consistent with the response to feeding behavior. In contrast, NF-κB and POMC genes were up-regulated, and their expression was increased by about 200% and 450%, respectively, with maximal response on Day 2. Moreover, NF-κB DNA binding ability and expression were increased similar to that of POMC. To examine further if NF-κB was involved, intracerebroventricular infusion of NF-κB antisense oligonucleotide was performed 1 h before the daily AMPH dosing in freely moving rats. Results showed that NF-κB knockdown could modify AMPH anorexia as well as NPY and POMC expression. The present findings prove that cerebral NF-κB participates in AMPH-mediated appetite suppression, possibly by modulating NPY and POMC expression. These results may aid in therapeutic research on AMPH and AMPH-like anti-obesity drugs.

Knocking down the transcript of NF-kappaB modulates the reciprocal regulation of endogenous antioxidants and feeding behavior in phenylpropanolamine-treated rats.

It has been reported that oxidative stress, antioxidants, and neuropeptide Y (NPY) are involved in regulating the feeding behavior of phenylpropanolamine (PPA), a sympathomimetic drug. This study explored whether transcription factor NF-κB is involved in this effect. Rats were treated daily with PPA for 4 days. Changes in hypothalamic NF-κB, NPY, superoxide dismutase (SOD), and glutathione peroxidase (GPx) levels during PPA treatment were assessed and compared. Results showed that NF-κB, SOD, and GPx increased, with a maximal response on Day 2, while the food intake and NPY decreased with the biggest reduction on Day 2 during PPA treatment. To further determine whether NF-κB was involved, intracerebroventricular infusion of antisense oligonucleotide was performed at 1 h before daily PPA in free-moving rats. Cerebral NF-κB knockdown could modify PPA anorexia and the expressions of NPY, SOD, and GPx. It is suggested that hypothalamic NF-κB participates in the reciprocal regulation of NPY and antioxidants, which mediated the appetite-suppressing effect of PPA. Results may further the understanding of the molecular mechanisms of PPA.

Role of reactive oxygen species-related enzymes in neuropeptide y and proopiomelanocortin-mediated appetite control: a study using atypical protein kinase C knockdown.

AIMS: Studies have reported that redox signaling in the hypothalamus participates in nutrient sensing. The current study aimed to determine if the activation of reactive oxygen species-related enzymes (ROS-RE) in the hypothalamus participates in regulating neuropeptide Y (NPY)-mediated eating. Moreover, possible roles of proopiomelanocortin (POMC) and atypical protein kinase C (aPKC) were also investigated. Rats were treated daily with phenylpropanolamine (PPA) for 4 days. Changes in the expression levels of ROS-RE, POMC, NPY, and aPKC were assessed and compared. RESULTS: Results showed that ROS-RE, POMC, and aPKC increased, with a maximal response on Day 2 (anorectic effect) and with a restoration to the normal level on Day 4 (tolerant effect). By contrast, NPY expression decreased, and the expression pattern of NPY proved opposite those of ROS-RE and POMC. Central inhibition of ROS production by ICV infusion of ROS scavenger attenuated PPA anorexia, revealing a crucial role of ROS in regulating eating. Cerebral aPKC knockdown by ICV infusion of antisense aPKC modulated the expression of ROS-RE, POMC, and NPY. CONCLUSION: Results suggest that ROS-RE/POMC- and NPY-containing neurons function reciprocally in regulating both the anorectic and tolerant effects of PPA, while aPKC is upstream of these regulators. INNOVATION: These results may further the understanding of ROS-RE and aPKC in the control of PPA anorexia.