Ginkgo biloba Extract (GbE) Restores Serotonin and Leptin Receptor Levels and Plays an Antioxidative Role in the Hippocampus of Ovariectomized Rats.

Since Ginkgo biloba extract (GbE) was reported to improve the hypothalamic serotonergic system of ovariectomized (OVX) rats, the present study aimed to verify the GbE effects on hippocampal oxidative stress, inflammation, and levels of the serotonin transporter (5-HTT), and both the serotonin (5-HT1A, 5-HT1B) and leptin receptors of OVX rats. Two-month-old female Wistar rats had their ovaries surgically removed (OVX) or not (SHAM). After 60 days, OVX rats were gavaged daily with GbE 500 mg kg-1 (OVX+GbE), while SHAM and OVX groups received saline 0.9% (vehicle) for 14 days. Rats were then euthanized, and hippocampi were collected. Both 5-HT1A and 5-HT1B levels were significantly reduced in OVX rats compared to SHAM rats, while 5-HT1A was higher in OVX+GbE rats in comparison to OVX rats. Similarly, LepR levels were increased in OVX+GbE rats compared to OVX rats, reaching similar levels to SHAM rats. Superoxide dismutase activity increased in OVX rats in relation to SHAM rats, which was restored to SHAM levels by GbE treatment. Additionally, GbE significantly increased the glutathione peroxidase activity in comparison to the SHAM group. No differences were observed either in catalase activity or in the levels of 5-HTT, PKCα, TLR-4, NF-κBp50, ERK, and CREB. In summary, our results show a potential effect of GbE on hippocampal pathways involved in feeding behavior, and thus, they suggest that GbE activity might improve menopausal-related hippocampal disorders, offering an alternative therapeutic tool particularly for women to whom hormone replacement therapy may be contraindicated.

Ginkgo biloba extract (GbE) attenuates obesity and anxious/depressive-like behaviours induced by ovariectomy.

While several pieces of evidence link obesity and mood disorders in menopause, the mechanisms involved are not yet fully understood. We have previously demonstrated that Ginkgo biloba extract (GbE) both attenuated diet-induced obesity of male rats and restored serotonin-induced hypophagia in ovariectomized female rats. The present study aimed at exploring whether GbE treatment ameliorates ovariectomy-related obesity and anxious/depressive-like behaviours. Wistar female rats were either ovariectomized (OVX) or sham-operated (Sham). After 2 months, either 500 mg/kg of GbE or vehicle were administered daily by gavage for 14 days. Anxious/depressive-like behaviours were assessed by the Elevated Plus Maze and the Forced Swim Tests, respectively. Ovariectomy caused high visceral adiposity, hyperleptinemia, and hypercholesterolemia, and increased the anxiety index (p = 0.048 vs. Sham + GbE) while it decreased the latency to immobility (p = 0.004 vs. Sham). GbE treatment in OVX rats improved body composition, adiponectin levels and blood lipid profile. It also reduced the anxiety index (p = 0.004) and increased the latency to immobility (p = 0.003) of OVX rats. Linear regression analysis demonstrated that leptin (p = 0.047) and total cholesterol levels (p = 0.022) were associated with anxious-like behaviours while body adiposity (p = 0.00005) was strongly associated with depressive-like behaviours. The results showed that GbE therapy was effective in attenuating the deleterious effects of ovariectomy on body composition, lipid profile, and anxious/depressive-like behaviours. Further studies are warranted to better understand the therapeutic potential of GbE in menopause.

Protective effect of soybean oil- or fish oil-rich diets on allergic airway inflammation.

BACKGROUND: The increased prevalence of asthma and allergic diseases in westernized societies has been associated with increased intake of diets rich in n-6 fatty acids (FAs) and poor in n-3 FAs. This study aimed to analyze the prophylactic effects of treatment with a soybean oil-rich diet (rich in n-6) or fish oil (rich in n-3) in an allergic airway inflammation model on lung inflammation score, leukocyte migration, T-helper cell (Th)-2 (interleukin [IL]-4, IL-5) and Th1 (interferon [IFN]-γ, tumor necrosis factor-α) cytokines, lipoxin A4, nitric oxide, bradykinin, and corticosterone levels in bronchoalveolar lavage (BAL) or lungs. METHODS: Male Wistar rats fed with soybean oil- or fish oil-rich diet or standard rat chow were sensitized twice with ovalbumin-alumen and challenged twice with ovalbumin aerosol. The BAL and lungs were examined 24 hours later. RESULTS: Both diets, rich in n-6 or n-3 FAs, impaired the allergic lung inflammation and reduced leukocyte migration, eosinophil and neutrophil percentages, and IL-4/IL-5/bradykinin levels in BAL and/or lungs, as well as increased the nitric oxide levels in BAL. The soybean oil-rich diet additionally increased the levels of lipoxin A4 and corticosterone in the lungs. CONCLUSION: Data presented demonstrated that the n-6 FA-rich diet had protective effect upon allergic airway inflammation and was as anti-inflammatory as the n-3 FA-rich diet, although through different mechanisms, suggesting that both diets could be considered as complementary therapy or a prophylactic alternative for allergic airway inflammation.

Ginkgo biloba extract improves insulin signaling and attenuates inflammation in retroperitoneal adipose tissue depot of obese rats.

Due to the high incidence and severity of obesity and its related disorders, it is highly desirable to develop new strategies to treat or even to prevent its development. We have previously described that Ginkgo biloba extract (GbE) improved insulin resistance and reduced body weight gain of obese rats. In the present study we aimed to evaluate the effect of GbE on both inflammatory cascade and insulin signaling in retroperitoneal fat depot of diet-induced obese rats. Rats were fed with high fat diet for 2 months and thereafter treated for 14 days with 500 mg/kg of GbE. Rats were then euthanized and samples from retroperitoneal fat depot were used for western blotting, RT-PCR, and ELISA experiments. The GbE treatment promoted a significant reduction on both food/energy intake and body weight gain in comparison to the nontreated obese rats. In addition, a significant increase of both Adipo R1 and IL-10 gene expressions and IR and Akt phosphorylation was also observed, while NF-κB p65 phosphorylation and TNF-α levels were significantly reduced. Our data suggest that GbE might have potential as a therapy to treat obesity-related metabolic diseases, with special interest to treat obese subjects resistant to adhere to a nutritional education program.

L-arginine abolishes the hypothalamic serotonergic activation induced by central interleukin-1ß administration to normal rats.

IL-1ß-induced anorexia may depend on interactions of the cytokine with neuropeptides and neurotransmitters of the central nervous system control of energy balance and serotonin is likely to be one catabolic mediator targeted by IL-1ß. In the complex interplay involved in feeding modulation, nitric oxide has been ascribed a stimulatory action, which could be of significance in counteracting IL-1ß effects.The present study aims to explore the participation of the nitric oxide and the serotonin systems on the central mechanisms induced by IL-1ß and the relevance of their putative interactions to IL-1ß hypophagia in normal rats.Serotonin levels were determined in microdialysates of the ventromedial hypothalamus after a single intracerebroventricular injection of 10 ng of IL-1ß , with or without the pre-injection of 20 µg of the nitric oxide precursor L-arginine. IL-1ß significantly stimulated hypothalamic serotonin extracellular levels, with a peak variation of 130 ± 37% above baseline. IL- 1ß also reduced the 4-h and the 24-h food intakes (by 23% and 58%, respectively). The IL-1ß-induced serotonergic activation was abolished by the pre-injection of L-arginine while the hypophagic effect was unaffected.The data showed that one central effect of IL-1ß is serotonergic stimulation in the ventromedial hypothalamus, an action inhibited by nitric oxide activity. It is suggested that, although serotonin participates in IL-1ß anorexia, other mechanisms recruited by IL-1ß in normal rats are able to override the absence of the serotonergic hypophagic influence.

Fatty acids in plasma, white and red blood cells, and tissues after oral or intravenous administration of fish oil in rats.

BACKGROUND & AIMS: The importance of route of administration of omega-3 (n-3) polyunsaturated fatty acids (PUFA) (oral vs intravenous (iv)) is not clear. We determined the relative concentrations of fatty acids in plasma phosphatidylcholine (PC), red blood cells (RBC), white blood cells (WBC) and several tissues after short-term oral or iv administration of soybean oil (SO) or fish oil (FO). METHODS: Wistar rats (n = 6/group) received saline, FO, or SO by gavage or saline, FO based-lipid emulsion (FLE), or SO based-lipid emulsion (SLE) iv. The oils were provided at 0.2 g/kg/day for three consecutive days. The animals were sacrificed 24 h after the last administration, blood was collected for plasma, WBC and RBC separation and tissues removed. Fatty acids were analysed by gas chromatography. RESULTS: FO resulted in higher eicosapentaenoic acid (EPA) in plasma PC and liver than the control. FLE resulted in higher EPA, docosahexaenoic acid (DHA) and total n-3 PUFA in plasma PC, WBC and liver than both the control and SLE groups. EPA, DHA and total n-3 PUFA were higher in the heart with FLE compared with SLE. Individual and total n-3 PUFA were higher in plasma PC, WBC, liver and heart with FLE than with FO given by gavage. CONCLUSION: Short-term iv administration of n-3 PUFA appears to be more effective at increasing EPA and DHA status in plasma, WBC, liver and heart than oral administration. This might be important for rapid treatment with n-3 PUFA.

Lateral hypothalamic serotonin is not stimulated during central leptin hypophagia.

Whether leptin targets the hypothalamic serotonergic system to inhibit food intake is not established. We examined the effect of a short-term i.c.v. leptin treatment on serotonin microdialysate levels in rat lateral hypothalamus. Adipose tissue gene expression was also evaluated. Male rats received four daily injections of leptin (5 µg) or vehicle (with pair-feeding to leptin-induced intake) and a fifth injection during collection of LH microdialysates. We found that serotonin and 5-HIAA levels were not affected by the leptin pre-treatment, as basal levels were similar between the leptin and the pair-fed group. These levels remained unaltered after the acute leptin injection. For gene expression studies, rats were pre-treated with five daily injections of either leptin (5 µg) or vehicle (with either pair-feeding or ad libitum intake). mRNA levels of resistin, adiponectin, lipoprotein lipase, and PPAR-gamma were unaltered by either leptin or pair-feeding. Leptin gene expression was significantly reduced by leptin but not by pair-feeding, in both the retroperitoneal (-74%) and the epididymal (-99%) depots while no differences were observed in the subcutaneous depot. The observations confirmed the absence of an acute stimulatory effect of central leptin on serotonin release in the lateral hypothalamus and showed that the pre-treatment with leptin failed to modify this pattern. This indicates that components of the serotonergic system are probably not directly affected by leptin. Additionally, the central effect of leptin was able to downregulate its own adipose tissue gene expression in a depot-specific manner while other adipokine genes were not affected.

Long-term consumption of fish oil-enriched diet impairs serotonin hypophagia in rats.

Hypothalamic serotonin inhibits food intake and stimulates energy expenditure. High-fat feeding is obesogenic, but the role of polyunsaturated fats is not well understood. This study examined the influence of different high-PUFA diets on serotonin-induced hypophagia, hypothalamic serotonin turnover, and hypothalamic protein levels of serotonin transporter (ST), and SR-1B and SR-2C receptors. Male Wistar rats received for 9 weeks from weaning a diet high in either soy oil or fish oil or low fat (control diet). Throughout 9 weeks, daily intake of fat diets decreased such that energy intake was similar to that of the control diet. However, the fish group developed heavier retroperitoneal and epididymal fat depots. After 12 h of either 200 or 300 µg intracerebroventricular serotonin, food intake was significantly inhibited in control group (21-25%) and soy group (37-39%) but not in the fish group. Serotonin turnover was significantly lower in the fish group than in both the control group (-13%) and the soy group (-18%). SR-2C levels of fish group were lower than those of control group (50%, P = 0.02) and soy group (37%, P = 0.09). ST levels tended to decrease in the fish group in comparison to the control group (16%, P = 0.339) and the soy group (21%, P = 0.161). Thus, unlike the soy-oil diet, the fish-oil diet decreased hypothalamic serotonin turnover and SR-2C levels and abolished serotonin-induced hypophagia. Fish-diet rats were potentially hypophagic, suggesting that, at least up to this point in its course, the serotonergic impairment was either compensated by other factors or not of a sufficient extent to affect feeding. That fat pad weight increased in the absence of hyperphagia indicates that energy expenditure was affected by the serotonergic hypofunction.

Prolonged consumption of soy or fish-oil-enriched diets differentially affects the pattern of hypothalamic neuronal activation induced by refeeding in rats.

We used c-Fos immunoreactivity to estimate neuronal activation in hypothalamic feeding-regulatory areas of 3-month-old rats fed control or oil-enriched diets (soy or fish) since weaning. While no diet effect was observed in c-Fos immunoreactivity of 24-h fasted animals, the acute response to refeeding was modified by both hyperlipidic diets but with different patterns. Upon refeeding, control-diet rats had significantly increased c-Fos immunoreactivity only in the paraventricular hypothalamic nucleus (PVH, 142%). In soy-diet rats, refeeding with the soy diet increased c-Fos immunoreactivity in dorsomedial hypothalamic nucleus (DMH, 271%) and lateral hypothalamic area (LH, 303%). Refeeding fish-diet rats with the fish diet increased c-Fos immunoreactivity in PVH (161%), DMH (177%), VMH (81%), and ARC (127%). Compared to the fish-diet, c-Fos immunoreactivity was increased in LH by the soy-diet while it was decreased in ventromedial hypothalamic nucleus (VMH) and arcuate hypothalamic nucleus (ARC). Based on the known roles of the activated nuclei, it is suggested that, unlike the fish-diet, the soy-diet induced a potentially obesogenic profile, with high LH and low VMH/PVH activation after refeeding.

Impairment of the serotonergic control of feeding in adult female rats exposed to intra-uterine malnutrition.

We have previously shown that adult female rats exposed to intra-uterine malnutrition were normophagic, although obese and resistant to insulin-induced hypophagia. The present study aimed at examining aspects of another important catabolic component of energy homeostasis control, the hypothalamic serotonergic function, which inhibits feeding and stimulates energy expenditure. Pregnant dams were fed ad libitum or were restricted to 50 % of ad libitum intake during the first 2 weeks of pregnancy. Control and restricted 4-month-old progeny were studied. The restricted rats had increased body adiposity with normal daily food intake but failed to respond with hypophagia to an intracerebroventricular injection of serotonin (5-hydroxytryptamine; 5-HT). Stimulation, by food ingestion, of extracellular levels of serotonin in medial hypothalamus microdialysates was more pronounced and lasted longer in the restricted than in the control rats. In the restricted group, hypothalamic levels of 5-HT 2C receptor protein tended to be reduced (P = 0.07) while the levels of 5-HT1B receptor and serotonin transporter proteins were significantly elevated (36 and 79 %, respectively). In conclusion, female rats undernourished in utero had normophagic obesity as adults but had an absence of serotonin-induced hypophagia and low hypothalamic levels of the 5-HT 2C receptor. Compensatory adaptations for the functional serotonergic impairment were evidenced, such as an enhanced release of serotonin in response to a meal allied to up-regulated hypothalamic 5-HT1B and transporter expression. Whether these compensations will persist in later life warrants further investigation. Moreover, it cannot be ruled out that the serotonergic component of energy expenditure was already impaired, thus contributing to the observed body-fat phenotype.

Central administration of a nitric oxide precursor abolishes both the hypothalamic serotonin release and the hypophagia induced by interleukin-1beta in obese Zucker rats.

Serotonin-induced anorexia has long been recognized as an important part of the CNS mechanisms controlling energy balance. More recently, interleukin-1beta and nitric oxide have been suggested to influence this control, possibly through modulation of hypothalamic serotonin. The present work aimed at investigating the interaction of these systems. We addressed whether 5-HT is affected during IL-1beta-induced anorexia in obese Zucker rats and the influence of the central NO system on this IL-1beta/5-HT interaction. Using microdialysis, we observed that an intracerebroventricular injection of 10 ng IL-1beta significantly stimulated 5-HT extracellular levels in the VMH, with a peak variation of 102+/-41% above baseline. IL-1beta also significantly reduced the 4-h feeding by 33% and the 24-h feeding by 42%. Contrarily, these effects were absent when IL-1beta was injected 2 h after the i.c.v. administration of 20 microg of the NO precursor L-arginine. The results suggest that, in obese Zucker rats, activation of the serotonergic system in the medial hypothalamus participates in IL-1beta-induced anorexia. Since L-arginine, probably through NO stimulation, abolished both the anorexia and the serotonergic activation, it can be proposed that the NO system, either directly or indirectly, counteracts IL-1beta anorexia. The hypothalamic serotonergic system is likely to mediate this NO effect.