English and Black Walnut Phenolic Antioxidant Activity in Vitro and Following Human Nut Consumption

ABSTRACT Background: Walnut consumption may reduce the risk of cardiovascular disease by providing antioxidant protection to low density lipoproteins (LDL). Aim: This study compared the phenolic profile and antioxidant activity of English versus black walnuts. Methods: Nuts were extracted in methanol or acetone prior to analysis with HPLC/LC-MS-MS for phenolic identification and quantitation. The ability to prevent oxidation of LDL was examined in vitro using walnut extracts and ex vivo after walnut consumption for 28 days. Results: Flavonoids identified/quantified with HPLC/LC-MS-MS included the phenolic acids 5-caffeoylquinic acid, 3-caffeoylquinic acid (black walnut only), 4-caffeoylquinic acid, and the flavonol glycosides querceti

A relationship between reduced nucleus accumbens shell and enhanced lateral hypothalamic orexin neuronal activation in long-term fructose bingeing behavior.

Fructose accounts for 10% of daily calories in the American diet. Fructose, but not glucose, given intracerebroventricularly stimulates homeostatic feeding mechanisms within the hypothalamus; however, little is known about how fructose affects hedonic feeding centers. Repeated ingestion of sucrose, a disaccharide of fructose and glucose, increases neuronal activity in hedonic centers, the nucleus accumbens (NAc) shell and core, but not the hypothalamus. Rats given glucose in the intermittent access model (IAM) display signatures of hedonic feeding including bingeing and altered DA receptor (R) numbers within the NAc. Here we examined whether substituting fructose for glucose in this IAM produces bingeing behavior, alters DA Rs and activates hedonic and homeostatic feeding centers. Following long-term (21-day) exposure to the IAM, rats given 8-12% fructose solutions displayed fructose bingeing but unaltered DA D1R or D2R number. Fructose bingeing rats, as compared to chow bingeing controls, exhibited reduced NAc shell neuron activation, as determined by c-Fos-immunoreactivity (Fos-IR). This activation was negatively correlated with orexin (Orx) neuron activation in the lateral hypothalamus/perifornical area (LH/PeF), a brain region linking homeostatic to hedonic feeding centers. Following short-term (2-day) access to the IAM, rats exhibited bingeing but unchanged Fos-IR, suggesting only long-term fructose bingeing increases Orx release. In long-term fructose bingeing rats, pretreatment with the Ox1R antagonist SB-334867 (30 mg/kg; i.p.) equally reduced fructose bingeing and chow intake, resulting in a 50% reduction in calories. Similarly, in control rats, SB-334867 reduced chow/caloric intake by 60%. Thus, in the IAM, Ox1Rs appear to regulate feeding based on caloric content rather than palatability. Overall, our results, in combination with the literature, suggest individual monosaccharides activate distinct neuronal circuits to promote feeding behavior. Specifically, long-term fructose bingeing activates a hyperphagic circuit composed in part of NAc shell and LH/PeF Orx neurons

Ox1R antagonist pretreatment reduced feeding-induced neuronal activation only in the control IAM group.

<p><b>A:</b> Orx neuron Fos-IR in LH/PeF, <b>B:</b> Fos-IR in the NAc shell, and <b>C:</b> Fos-IR in VMH following vehicle (Veh.) or SB-334867 (SB) pretreatment and 1^st hr bingeing on day 22 of IAM (see Fig. 4 for treatment details). Mean values ± SEM (n = 6–9 animals/group) *p<0.05 within feeding group 1-way ANOVA.</p

Both long- and short-term IAM produced similar levels of bingeing behavior.

<p><b>A:</b> 1^st hr water (black symbols; control) or fructose (blue symbols; 8% fructose) intake on days 1 and 2 for the short-term IAM experiment (closed symbols) and on days 1, 2, 8 and 21 for the long-term IAM experiment (open symbols). <b>B:</b> 1^st hr chow intake on days 1 and 2 of short-term IAM and days 1, 2, 6, and 21 of long-term IAM. ∧ denotes the day at which stable fructose or chow bingeing was achieved in the long-term IAM experiment. *p<0.05 paired t-test short-term IAM only. Mean values ± SEM (n = 8/group).</p

Ox1R antagonist pretreatment reduced caloric intake in both IAM feeding groups.

<p><b>A:</b> 1^st hr total liquid intake for <i>ad libitum</i> water (white column) and additional bottle, containing water (diagonal striped) or 8% fructose (blue column), for control and fructose groups on day 21 of IAM (no injection) and on day 22 of IAM after a 30-min pretreatment with vehicle (2% DMSO and 10% β-cyclodextrin in sterile water; Veh.) or SB-334867 (30 mg/kg, i.p; SB) <b>B:</b> The 1^st hr caloric intake, expressed as chow (horizontal striped columns) and 8% fructose (in blue columns) calories. Red lines indicate day 1 intake of water or fructose in panel A and calories in panel B. Mean values ± SEM (n = 6–9/group) *p<0.05 within group 1-way RMANOVA compared to day 21.</p

Fos-IR in Orx-IR neurons after long- or short-term IAM.

<p>Mean values ± SEM *p<0.05 control vs. fructose, unpaired t-test n = 7–8/group.</p

Long-term fructose bingeing reduced NAc shell neuron and enhanced LH/PeF Orx neuron activation.

<p>Immunohistochemical (IHC) staining results following long-term IAM (see Fig. 2). <b>A:</b> Anatomic outlines of NAc shell and core with enlarged representative images of IHC staining in NAc shell from control (Ctrl.) and 8% fructose (Fruc.) group animals with Fos-IR in green and Nissl stain in blue. <b>B:</b> Group results for NAc shell Fos-IR. <b>C:</b> Anatomic outlines of LH/PeF and DMH with enlarged representative images of IHC staining in Ctrl. and Fruc. group animals. The Fos-IR nuclei are in green, Orx-IR cells are in fuchsia and Nissl stain is in blue. <b>D:</b> Group results for the ratio of Orx neuron activation (Fos-IR nuclei in Orx-IR cells) in the LH/PeF. <b>E:</b> Significant negative correlation between LH/PeF Orx neuron activation and NAc shell neuron activation in the fructose IAM group. <b>F:</b> No correlation in the control IAM group. Dotted bands represent 95% confidence intervals of the linear regression. Mean values ± SEM (n = 7–8 per group) *p<0.05 unpaired t-test. Abbreviations: anterior commissure (ac), lateral ventricle (LV), fornix (f).</p

Fos-IR in hypothalamic and reward-related regions.

<p>Mean Fos-IR/mm² values ± SEM, *p<0.05 control vs. fructose, unpaired t-test n = 7–8/group.</p