title: Neuromodulation by soy diets or equol: anti-depressive & anti-obesity-like influences, age- & hormone-dependent effects.
abstract: BACKGROUND
  Soy-derived isoflavones potentially protect against obesity and depression. In five different studies we examined the influence of soy-containing diets or equol injections on depression, serotonin levels, body weight gain (BW) and white adipose tissue (WAT) deposition in female Long-Evans rats at various stages of life [rats were intact, ovariectomized or experienced natural ovarian failure (NOF)].
  
  
  RESULTS
  In general, animals fed a soy-rich diet (Phyto-600) and/or administered equol (@ 5 mg/kg/day) displayed significant decreases in BW and WAT compared to a low-soy diet. When equol was injected alone (5 mg/kg/day), experiments 1, 4, and 5 demonstrated that body weight was significantly decreased. Equol has body weight control effects in females that are dependent on ovarian status and/or age of diet initiation. Experiments 1-4 all displayed no significant differences in depressive-related behavior as measured by the Prosolt forced swim test (PFST) when soy-rich (Phyto-600) or low-soy diets (Phyto-low) or equol treatments (5 mg/kg/day) were tested in female rats at various ages or hormonal status. Results of all the experiments are not presented here due to space limitations, but data from experiment 5 are presented. From conception female rats were exposed to either: a) a soy-rich (Phyto-600) or b) low-soy diet (Phyto-low). After 290 days all rats experienced NOF. At 330 days-old the animals were examined in the Porsolt forced swim test (PFST). One month later a second PFST was performed [after Phyto-low fed animals were injected with equol (5 mg/kg/day) for one week prior to the second PFST]. At the first PFST, serotonin and mobility levels were significantly decreased in the Phyto-low fed animals compared to animals that consumed the Phyto-600 diet. After equol injections at the second PFST, mobility and serotonin levels significantly increased in aged NOF rats fed the Phyto-low diet (to levels comparable to Phyto-600 fed animals).
  
  
  CONCLUSIONS
  Consumption of dietary isoflavones or equol exposure in rats has body weight controlling effects and equol specifically may have antidepressant potential dependent upon diet initiation and/or dosage of treatments. The current study demonstrates that equol is able to decrease body weight, abdominal WAT, and depressive-related behavior. While other factors and mechanisms may play a role, in part, the present results provide a greater understanding of how isoflavonoid molecules modulate the brain's influence on behavior.
authors.affiliation: Department of Physiology and Developmental Biology and The Neuroscience Center, Brigham Young University, Provo, Utah 84602, USA.
authors.forename: Crystal
authors.initials: C
authors.lastname: Blake
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Fabick
authors.forename: Kenneth Dr
authors.initials: KD
authors.lastname: Setchell
authors.forename: Trent D
authors.initials: TD
authors.lastname: Lund
authors.forename: Edwin D
authors.initials: ED
authors.lastname: Lephart
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D003863:Depression / Q000097:blood / Q000178:diet therapy* / Q000503:physiopathology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D060754:Equol; D005260:Female; D006728:Hormones / Q000097:blood*; D007529:Isoflavones / Q000008:administration & dosage*; D008297:Male; D009765:Obesity / Q000097:blood / Q000178:diet therapy*; D009929:Organ Size / Q000187:drug effects / Q000502:physiology; D010052:Ovariectomy; D048789:Phytoestrogens / Q000008:administration & dosage* / Q000097:blood; D051381:Rats; D012701:Serotonin / Q000378:metabolism; D030262:Soybean Proteins / Q000008:administration & dosage*; D013025:Glycine max / Q000737:chemistry; D018709:Statistics, Nonparametric; D013550:Swimming / Q000523:psychology
chemical_list: C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D006728:Hormones; D007529:Isoflavones; D048789:Phytoestrogens; D030262:Soybean Proteins; D012701:Serotonin; D060754:Equol