Expanded insights into the neural component of the activity-based anorexia animal model - morphological changes in the enteric nervous system and altered pain perception.

Anorexia nervosa (AN) is an eating disorder characterized by distinct etiopathogenetic concepts that are gradually being linked together to unravel the dominant pathophysiological pathways underlying the disease. Excessive food restrictions, often accompanied by over-exercise and undertaken to lose weight, lead to the development of numerous complications. The biological concept of neurohormonal dysfunction in AN seems incomplete without demonstrating or excluding the role of the enteric nervous system (ENS). Using an animal model of activity-based anorexia (ABA), we conducted the preliminary assessment of the ENS structure. Here we show, in preparations stained by immunohistochemistry with anti- ChAT, anti-NOS, anti-PGP 9.5, anti-c-fos, and anti-TH antibodies, a lower density of cholinergic and nitrergic nerve fibers as well as reduced neuronal activity in myenteric plexus. Such structural and functional damage to the ENS may be responsible for a number of gastrointestinal symptoms that worsen the course of the disease. In addition, we expanded the study to address the unresolved issue of mechanical and thermal pain sensitivity in AN. The Von Frey and hot plate tests revealed, that in ABA animals, the pain threshold for mechanical stimulus decreases while for thermal increases. In this way, we have significantly supplemented the background of AN with potentially observable nervous system changes which may influence the evolution of the therapeutic approach in the future.

Is the Activity-Based Anorexia Model a Reliable Method of Presenting Peripheral Clinical Features of Anorexia Nervosa?

Anorexia nervosa (AN) causes the highest number of deaths among all psychiatric disorders. Reduction in food intake and hyperactivity/increased anxiety observed in AN are also the core features of the activity-based anorexia animal model (ABA). Our aim was to assess how the acute ABA protocol mimics common AN complications, including gonadal and cardiovascular dysfunctions, depending on gender, age, and initial body weight, to form a comprehensive description of ABA as a reliable research tool. Wheel running, body weight, and food intake of adolescent female and male rats were monitored. Electrocardiography, heart rate variability, systolic blood pressure, and magnetic resonance imaging (MRI) measurements were performed. Immediately after euthanasia, tissue fragments and blood were collected for further analysis. Uterine weight was 2 times lower in ABA female rats, and ovarian tissue exhibited a reduced number of antral follicles and decreased expression of estrogen and progesterone receptors. Cardiovascular measurements revealed autonomic decompensation with prolongation of QRS complex and QT interval. The ABA model is a reliable research tool for presenting the breakdown of adaptation mechanisms observed in severe AN. Cardiac and hormonal features of ABA with underlying altered neuroendocrine pathways create a valid phenotype of a human disease.

Effect of 5-fluorouracil on branched-chain α-keto acid dehydrogenase (BCKDH) complex in rat's heart.

Undisturbed branched-chain amino acids (BCAA) catabolism is necessary for normal heart function. The key enzyme in BCAA catabolism is a multienzyme branched-chain α-keto acid dehydro- genase complex (BCKDH). BCKDH activity is regulated mainly by reversible dephosphorylation (activa- tion)/phosphorylation (inactivation) cycle catalyzed by regulatory enzymes, a specific phosphatase (PPM1K) and kinase (BDK). 5-fluorouracil (5-FU) is widely used in the treatment of different types of cancer. 5-FU has the potential to cause a wide spectrum of cardiotoxicity, ranging from asymptomatic electrocardiographic changes to cardiomyopathy and subsequent cardiac failure. We hypothesize that 5-FU modifies BCKDH activity and affects cardiac muscle metabolism. The current study was aimed at the investigation of the in vivo effect of 5-FU on BCKDH activity and mRNA levels for E1, PPM1K and BDK. Wistar male rats were administered with 4 doses of 5-FU, 150 mg/kg b.wt. each (study group) or 0.3% methylcellulose (control group). BCKDH activity was assayed spectrophotometrically. The mRNA levels were quantified by real-time PCR. 5-FU treatment caused an increase in BCKDH activity that appears to result mainly from increased dephosphorylation of the complex and is associated with an increase of PPM1K mRNA level and reduction of BDK and E1 mRNA levels. It is conceivable that 5-FU stimulation of BCKDH is an adaptive reaction with the purpose of enhancing the BCAA catabolism and protecting from toxic effect caused by excessive accumulation of these amino acids in heart.

Hypothalamic and brain stem neurochemical profile in anorectic rats after peripheral administration of kisspeptin-10 using 1 H-nmr spectroscopy in vivo.

PURPOSE: Although anorexia nervosa is classified as a psychiatric disorder associated with socio-environmental and psychological factors, a deeper insight into the dominant neurobiological basis is needed to develop a more effective approach of treatment. Given the high contribution of genetic predisposition and the underlying pathophysiology of neurohormonal circuits, it seems that pharmacological targeting of these mechanisms may provide us with better therapeutic outcomes. METHODS: 1 H-NMR spectroscopy was used to measure concentrations of the hypothalamus and brain stem metabolites in an activity-based rodent model (ABA) after subcutaneous administration of kisspeptin-10. Because anorexia mainly affects young women and often leads to hypogonadotropic-hypogonadism, we investigated the influence of this neuropeptide, which is involved in reproductive function by regulating the hypothalamic-pituitary-gonadal axis, on the ABA model development. RESULTS: Kisspeptin reinforced food consumption in an activity-based rodent model of anorexia changing a pattern of weight loss. 1 H-NMR spectroscopy of the hypothalamus and brain stem of ABA rats revealed a statistically significant change in the concentration of creatine (Cr; decreased, P = 0.030), phosphocreatine (PCr; increased, P = 0.030), γ-aminobutyric acid (GABA; decreased, P = 0.011), glutathione (GSH; increased, P = 0.011) and inositol (INS; increased, P = 0.047) compared to the control group. Subcutaneous administration of kisspeptin reversed the decrease in GABA (P = 0.018) and Cr (P = 0.030) levels in the hypothalamus as well as restored glutamate (GLU; P = 0.040) level in the brain stem. CONCLUSIONS: We suspect that kisspeptin through modulation of hypothalamic GABAergic signaling increases food intake, and thus positively alters brain metabolism.

Aberrations in the female reproductive organs and a role of telocytes in a rat model of anorexia nervosa.

BACKGROUND: Anorexia nervosa is a widely prevalent eating disorder that o en leads to life-threatening complications. Since it mostly concerns females, many authors have focused on studying the reproductive system in anorexic women. Recently discovered telocytes may give a new insight into the pathophysiology of gynecological complications in these patients. MATERIAL AND METHODS: We adopted an animal model of anorexia nervosa induced by voluntary physical activity. Sixteen female Wistar rats were divided into two groups: control and activity-based anorexia. When the weight loss of activity-based anorexia (ABA) rats reached 25% animals were euthanized. Size and weight measurements as well as histopathological analysis of the reproductive organs were performed. Additionally, we used immunohistochemical staining for detection of telocytes. RESULTS: Telocytes were identified in uteri of anorectic rats but no differences were observed when compared to the control group. Nevertheless, in the ABA group the weight of the uteri and the number of follicles in the ovaries decreased significantly. CONCLUSIONS: Our rat model of anorexia nervosa mimics the effects of this eating disorder that occur in the female reproductive system since we reported ovarian dysfunction and uterine involution in the experimental animals. It supports its potential role in the further studies of anorexia pathophysiology and treatment possibilities.