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Biomedical subjects

U Schweiger

Publications and source records attributed to U Schweiger.

At least 73 records · Page 4Linked to original sources

Serotonin turnover in rat brain during semistarvation with high-protein and high-carbohydrate diets.

Serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) were determined in seven brain regions of semistarved and control male rats. After semistarvation on a high carbohydrate diet serotonin turnover, as indicated by 5-HIAA/5-HT ratio, was increased in the total brain and several regions both three and 24 hours after the last meal. In contrast, after semistarvation on a high-protein diet serotonin turnover was decreased three hours after ingestion of the final meal, but increased 24 hours thereafter. Compulsary running wheel activity for one hour did not influence diet induce changes in serotonin turnover. Alterations in plasma corticosterone during semistarvation were not related to changes in central serotonin turnover. Data suggest that the interaction of caloric restriction and diet composition determines serotonin turnover during semi-starvation.

Animals↗

Dieting causes menstrual irregularities in normal weight young women through impairment of episodic luteinizing hormone secretion.

Thirteen healthy, normal weight young women were studied throughout a control cycle and a diet cycle, during which they lost 1 kg per week on a vegetarian 800 kcal diet. Blood was sampled daily in the morning, and at weekly intervals, collected at 10-minute intervals for 6 hours. Follicle growth was monitored by ultrasonic measurement. All subjects showed normal cyclic gonadal function during the control cycle. Cyclic gonadal function remained unaltered in two subjects during the diet cycle. No dominant follicle developed in seven others, while another four showed apparently normal follicular development but impaired progesterone secretion by the corpus luteum. Comparison of both cycles revealed that episodic luteinizing hormone (LH) secretion during the follicular phase was altered by dieting. Average LH concentrations and the frequency of episodic secretions were significantly reduced during the follicular phase but not during the luteal phase. Follicle-stimulating hormone was unaltered.

Adult↗

Neurochemical abnormalities of anorexia nervosa and bulimia nervosa.

The authors review the research on anorexia nervosa and bulimia nervosa, emphasizing the neurotransmitters and neuromodulators that regulate eating behavior. Anorexia nervosa is associated with changes in the noradrenergic, serotonergic, and opioid systems; bulimia nervosa is accompanied by marked alterations in serotonin and norepinephrine activity. These neurochemical changes may perpetuate pathological eating behavior and may be responsible for several associated psychiatric symptoms, including anxiety and depression. The authors also summarize studies of several drugs that are used in the treatment of eating disorders and are known to modify neurotransmitter activity. Understanding the neurochemistry of eating disorders seems crucial for the rational development of both psychopharmacological and behavioral treatments.

Anorexia Nervosa↗

Decreased follicular phase gonadotropin secretion is associated with impaired estradiol and progesterone secretion during the follicular and luteal phases in normally menstruating women.

We tested the hypothesis that disturbed follicular development and disturbed luteal progesterone (P4) secretion are associated with reduced gonadotropin secretion in the early follicular phase by measuring pulsatile LH and FSH secretion at that time in 53 normally menstruating women. Three groups of women were identified on the basis of serum sex steroid concentrations (measured daily throughout the cycle) and luteal phase length. Group A (n = 27) had normal ovarian hormone secretion with peak serum estradiol (E2) concentrations of 440 pmol/L or more, peak serum P4 concentrations of 19 nmol/L or more, and luteal phase length of 9 days or more. Group B (n = 16) had normal peak serum E2 values, but peak serum P4 values less than 19 nmol/L and/or luteal phase length less than 9 days. Group C (n = 10) had peak serum E2 values below 440 pmol/L. Risk factors for the disturbances found in groups B and C were exercise and/or intermittent dieting. Compared to group A, both groups B and C had reduced mean serum LH concentrations (3.1 +/- 1.5 vs. 2.3 +/- 1.4 and 2.0 +/- 1.0 IU/L; P less than 0.05) and reduced LH pulse frequencies (5.2 +/- 2.1 vs. 3.5 +/- 1.8 and 3.3 +/- 2.3 pulses/12 h; P less than 0.02). LH amplitude was similar in all 3 groups. Mean serum FSH concentrations were slightly but not significantly lower in group C. We conclude that reduced gonadotropin secretion during the follicular phase may indeed affect E2 and P4 secretion at later stages of the menstrual cycle. The patterns of alteration associated with disturbed E2 and P4 secretion in normally menstruating women are similar to those that occur in women with hypothalamic amenorrhea.

Adult↗

Depression as a correlate of starvation in patients with eating disorders.

The relationship between depressive symptoms and starvation, reflected by body weight and biochemical parameters, was investigated in 64 patients fulfilling DSM-III criteria for anorexia nervosa or bulimia. Multiple regression analysis revealed significant effects of body weight and beta-hydroxybutyric acid, respectively, on such specific depressive symptoms as depressed or dysphoric mood when controlling for severity of psychopathology of the eating disorder.

3-Hydroxybutyric Acid↗

Mood and orthostatic norepinephrine response in anorexia nervosa.

The relationship between mood and noradrenergic activity, measured by orthostatic norepinephrine response (delta NE), was investigated in 24 patients with anorexia nervosa during inpatient treatment. Mood and delta NE correlated significantly at four out of five measurement points. Group comparisons identified significantly worse mood in patients with pathologically low delta NE values. Thus, biological consequences of altered eating behavior may also affect such psychological symptoms as depressed mood.

Adult↗

Caloric intake, stress, and menstrual function in athletes.

The cause of menstrual disturbance in athletes is still debated. Apart from the acute and chronic effects of exertion, other associated behavioral variables are suspected to play a key role. A longitudinal study with frequent blood sampling was undertaken to link information about nutrition and stress with a quantitative assessment of endocrine menstrual function in 18 endurance-trained athletes and 25 age-matched, nonathletic women. Four athletes did not show hormonal signs of follicular development. The 14 athletes with cyclic gonadal function did not differ from controls with regard to estradiol concentrations during the follicular phase and at midcycle. During the luteal phase, however, they showed significantly reduced areas under the estradiol and progesterone curves. Caloric intake, as assessed by nutritional diaries, correlated positively with the area under the progesterone curve during the luteal phase (rs = 0.70, P less than 0.01). Ratings of subjective stress in the area "partner, family, friends" correlated negatively with the luteal progesterone area (rs = 0.80; P less than 0.01). Data support the hypothesis that nutrition and stress may play a critical role in the genesis of menstrual disturbance in athletes.

Adult↗

Diet-induced menstrual irregularities: effects of age and weight loss.

Luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and progesterone (P) levels were followed in 22 healthy, normal-weight women (aged 19 to 30 years) for a control and a diet menstrual cycle. During the diet cycle, they lost weight on a high-carbohydrate, vegetarian, 1000-calorie diet. During the control cycle, luteal phase in 5 subjects failed to meet the criteria: length greater than or equal to 8 days and P maximum greater than or equal to 6 ng/ml; during the diet cycle, the number of subjects who failed to meet these criteria was 14 (chi-square test, P less than 0.02). No evidence of follicular phase disturbance was observed during the diet. Age and weight loss significantly changed parameters of the diet luteal phase: length and area under LH, FSH, E2, and P curves. Generally, hormone plasma concentrations during the luteal phase were lower the younger the age and the greater the weight loss.

Adult↗

Disturbances of the menstrual cycle in bulimia nervosa.

Blood was obtained three times a week throughout one menstrual cycle or during a 6-week period from 15 patients with bulimia nervosa and from 10 healthy age-matched controls. Of the patients, three had amenorrhoea, eight had oligomenorrhoea and four had regular cycles. Normal follicular development, as judged from continuously low oestradiol (E2) values (less than 120 pg/ml or less than 440 pmol/l), did not occur in seven patients. Compared to patients with increasing E2 values (greater than 120 pg/ml), these seven had a significantly lower body weight. Among the eight patients showing follicular development (E2 greater than 120 pg/ml), four reported regular cycles, but only three developed normal plasma progesterone (P4) values during the luteal phase (P4 greater than 3 ng/ml or greater than 9.5 nmol/l). The luteal phase was of normal length in only one bulimic patient.

Adult↗

Macronutrient intake, plasma large neutral amino acids and mood during weight-reducing diets.

Influence of diet composition on mood during weight-reducing diets was studied in healthy young women of normal weight. A broad range of macronutrient intake was achieved by means of divergent dietary instructions for the composition of a 1,000 kcal per day diet adhered to for six weeks. Global mood during the last three weeks of the diet was significantly better in the "vegetarian" than in the "mixed" diet group. During this time a significant correlation was observed between relative carbohydrate intake and global mood (r = -0.74; p less than 0.01) and between the ratio of plasma tryptophan to other large neutral amino acids (a predictor of tryptophan flow into brain) and global mood (r = -0.52; p less than 0.05). Results suggest that group differences are related to differences in carbohydrate intake. It is hypothesized that impairment of central serotonergic function due to reduced tryptophan availability can prompt mood deterioration in situations of relatively low carbohydrate intake.

Adult↗

Effects of carbohydrate and protein meals on plasma large neutral amino acids, glucose, and insulin plasma levels of anorectic patients.

The response of large neutral amino acids (LNAA), glucose, and insulin plasma levels to a protein-rich and a carbohydrate-rich test meal was studied in anorectic patients (upon admission to hospital and after weight gain) and in a control group of young women. Patients showed reduced glucose tolerance, as well as increased and prolonged insulin secretion. After the protein meal, the ratio of tyrosine to other LNAA (a predictor of tyrosine flow into brain) was increased in patients and the ratio of tryptophan to other LNAA (a predictor of tryptophan flow into brain) depressed. The carbohydrate meal resulted in a smaller increase in the ratio of tryptophan to other LNAA in patients. Not all alterations showed a trend to normalization with weight gain. Implications of findings for monoamine metabolism and regulation of food choice are discussed.

3-Hydroxybutyric Acid↗

Dieting influences the menstrual cycle: vegetarian versus nonvegetarian diet.

Eighteen healthy, normal-weight women aged 19 to 27 years who had regular ovulatory menstrual cycles volunteered for the study. Blood was drawn on Mondays, Wednesdays, and Fridays throughout the control cycle and during a 6-week diet period that began with commencement of a new cycle. Nine women followed a vegetarian diet and nine a nonvegetarian diet. Both groups lost an average of 1 kg body weight/week. Seven of nine women in the vegetarian group became anovulatory. During the vegetarian diet the average luteinizing hormone (LH) values were significantly decreased during the midcycle and the luteal phase. Estradiol (E2) and progesterone (P) values were significantly lower during the luteal phase. In contrast, the nonvegetarian group did not show significant reduction of LH, E2, and P values during any part of the menstrual cycle. Seven of nine women in the nonvegetarian diet group maintained ovulatory cycles with no changes in cycle length or in the length of the follicular phase. In one woman who became anovulatory, E2 values did not increase during the follicular phase.

3-Hydroxybutyric Acid↗

Brain tyrosine availability and the depression of central nervous norepinephrine turnover in acute and chronic starvation in adult male rats.

Norepinephrine (NE) and 3-methoxy-4-hydroxyphenylglycol (MOPEG) were determined in medio-basal hypothalamus of adult male rats using high-performance liquid chromatography to study nutritional modulation of noradrenergic turnover. Acute starvation, as well as 3 weeks of semistarvation with a low-protein high-carbohydrate or high-protein low-carbohydrate diet decreased NE turnover significantly, as estimated by MOPEG concentration. Low-protein semistarvation resulted in subnormal concentrations of large neutral amino acids (LNAA), high-protein semistarvation in elevated concentrations. Tyrosine/LNAA ratio and calculated tyrosine flow into brain and brain tyrosine levels were reduced in both types of semistarvation. Corticosterone was low in low-protein and high in high-protein diet. These results suggest that tyrosine availability in brain potentially contributes to reduced NE turnover in starvation.

Animals↗

Anorectic behavior, mood, and metabolic and endocrine adaptation to starvation in anorexia nervosa during inpatient treatment.

Twenty-two patients with anorexia nervosa were studied at 2-week intervals during treatment on psychiatric wards. In order to characterize the metabolic situation in starvation, levels of free fatty acids, beta-hydroxybutyric acid, and acetoacetate were measured. The endocrine adaptation to starvation was studied by measuring triiodothyronine, noradrenaline, and cortisol. Anorectic symptoms were assessed by the Anorexia Nervosa Inventory Scale (ANIS) and mood changes on the basis of a "Befindlichkeits" Scale (BF). Only half of the patients showed metabolic and endocrine signs of starvation on admission to the hospital, despite low body weight. This group had significantly more severe anorectic symptoms (ANIS) and gained weight at a lesser rate. Metabolic signs of starvation disappeared during the first 4 weeks of therapy in most of the patients. The endocrine indicators for starvation normalized much more slowly, with noradrenaline having the slowest pace. "Bulimics" and "restricters" could not be distinguished from one another by metabolic or endocrine observations. The "bulimics," however, showed more severe anorectic symptoms (ANIS) and a more depressed mood.

Adolescent↗

Metabolic and endocrine indices of starvation in bulimia: a comparison with anorexia nervosa.

Fifteen patients with bulimia (DSM-III) and 22 patients with anorexia nervosa (10 "restricters" and 12 "vomiters") were compared with 24 age- and sex-matched healthy controls. Serial blood samples were collected between 8:30 and 9:30 a.m. with patients in supine and standing positions. Elevated blood values of beta-hydroxybutyric acid and free fatty acids were observed in the majority of patients with bulimia and anorexia nervosa. These data indicate that many patients with bulimia showed the metabolic signs of starvation at the time of the study, a finding supported by the symptoms of endocrine adaptation to starvation, namely low triiodothyronine and a decreased noradrenaline response to an orthostatic test in many of these patients.

3-Hydroxybutyric Acid↗

Norepinephrine turnover in the hypothalamus of adult male rats: alteration of circadian patterns by semistarvation.

Norepinephrine (NE) turnover, as estimated by 3-methoxy-4-hydroxyphenylethyleneglycol concentration, was studied in the mediobasal hypothalamus of control and semistarved adult male rats at eight time points of a 24-h period. The marked circadian periodicity of NE turnover with a peak in the dark phase in control rats is completely suppressed in semistarved rats. The average 24-h concentration of the NE precursor tyrosine in brain and of tyrosine flow into brain (calculated from plasma amino acid concentrations) is reduced in semistarved rats, but both brain tyrosine and tyrosine flow show continuing circadian fluctuations.

Animals↗

The influence of dieting on the menstrual cycle of healthy young women.

Nine normal young women of normal weight, aged 20-29 yr, who had regular menstrual cycles, dieted for 6 weeks (approximately 800-1000 kcal/day) and lost between 6 and 8 kg body wt. Half-hourly blood samples were taken from 1800-0530 h on two occasions before and after 1, 2, 3, 4, 5, and 6 weeks of dieting. In three women with anovulatory cycles the LH secretion pattern was not altered by dieting, but plasma estradiol levels decreased and reached menopausal concentrations during the final 2 weeks of dieting. In two of these three women the menstrual cycles were disrupted and regular cycles occurred only 3 and 6 months after dieting. Six women had regular ovulatory cycles. High progesterone values (greater than 3 ng/ml) were recorded in two cycles before the dieting period. While dieting, three women maintained ovulatory cycles and three women had no periovulatory hormone secretion pattern and/or a pattern characteristic of the luteal phase. No significant alterations of average LH concentrations and LH peak frequency developed. It is concluded that mild dieting does not suppress LH secretion in the manner found in anorexia nervosa or during total fasting. Dieting may interfere with gonadal steroid production, thus causing disturbances of the menstrual cycle. The effect described here may be responsible for the early onset of amenorrhea in patients with beginning anorexia nervosa.

Adult↗