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.
Departamento de Fisiologia, Universidade Federal de São Paulo, Rua Botucatu, São Paulo, SP, Brazil.
Regina L H
RL
Watanabe
Iracema S
IS
Andrade
Mônica M
MM
Telles
Kelse T
KT
Albuquerque
Cláudia M O
CM
Nascimento
Lila M
LM
Oyama
Dulce E
DE
Casarini
Eliane B
EB
Ribeiro
D000273:Adipose Tissue / Q000033:anatomy & histology; D000818:Animals; D004032:Diet; D004042:Dietary Fats, Unsaturated / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D005395:Fish Oils / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000737:chemistry / Q000378:metabolism; D007031:Hypothalamus / Q000737:chemistry / Q000378:metabolism; D057967:Infusions, Intraventricular; D008297:Male; D009929:Organ Size; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D044302:Receptor, Serotonin, 5-HT1B / Q000378:metabolism; D044405:Receptor, Serotonin, 5-HT2C / Q000378:metabolism; D012701:Serotonin / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism; D013024:Soybean Oil / Q000008:administration & dosage / Q000494:pharmacology
D004042:Dietary Fats, Unsaturated; D005395:Fish Oils; D044302:Receptor, Serotonin, 5-HT1B; D044405:Receptor, Serotonin, 5-HT2C; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D013024:Soybean Oil