Faculty Bibliography

Reproductive function in all vertebrates is controlled by the brain-pituitary-gonadal axis. In teleost fish, endocrine cells within the adenohypophysis are grouped together and each collection of cells is innervated by specific neuropeptide fibers. An important regulatory step in reproductive control is gonadotropin-releasing hormone (GnRH), whose delivery to the pituitary is responsible for its release of gonadotropins. The hormone GnRH has been shown to play a critical role in the social control of reproduction in a teleost fish, Haplochromis burtoni. However, there has been no direct evidence that the preoptic area GnRH neurons project to the pituitary. In this study, we used a retrograde tracer and immunohistochemistry to identify those GnRH containing neurons that project to the adenohypophysis. We compared reproductively active territorial males with quiescent non-territorial males to discover whether the connectivity of the preoptic area GnRH neurons depends on the reproductive status of the male. We found that, irrespective of reproductive status, most GnRH neurons in the preoptic area project to the pituitary and that all of these GnRH neurons show the soma size change that has been associated with reproductive status in Haplochromis burtoni. Based on these data, we propose that there is a single population of GnRH containing cells in the preoptic area that change size as a function of reproductive state and that this entire population projects to the pituitary. This is the first direct demonstration that this essential circuit, linking GnRH neurons in the preoptic area to the pituitary, exists

The effect of diazepam on the trade-off function between current and frequency for stimulation-induced feeding was evaluated in five rats with electrodes implanted in medial forebrain bundle structures. Three of the five exhibited stimulation-induced feeding (SIF) in vehicle tests, while in the remaining two attention to food was interspersed with periods of high activity. In all cases diazepam facilitated stimulation-induced feeding; the expression of stimulation-induced feeding was observed at a dose of 2.5 mg/kg and 5.0 mg/kg, where tested, and frequency threshold shifts ranged from 10% to 25%. The degree of facilitation was consistent across currents in two of the four pairs of trade-off functions examined. The results suggest that diazepam can facilitate stimulation-induced feeding and its expression in feeding sites with a competing arousal component

Nineteen bulimic women and 22 age-matched controls were randomly assigned to receive 25 g of glucose or a placebo injection under double-blind conditions. Blood samples of glucose, insulin, and glucagon, and psychometric assessments of mood and food cravings were obtained 10 min before, and 0, 5, 10, 20, 30, 45, and 60 min after injection. Blood levels of the large neutral amino acids (LNAAs) tryptophan, tyrosine, leucine, valine, phenylalanine, and leucine were determined at 10 min before and 60 min after the injection. Bulimic subjects were found to report more symptoms of distressed mood throughout the entire monitoring period than controls. Five minutes following glucose ingestion the self-reports of depression, fatigue, anxiety, and bewilderment rose to a level among the bulimic subjects that was above that at baseline, and was higher than that of bulimia nervosa (BN) subjects receiving placebo. No comparable change in mood was observed among controls. Blood glucose levels were correlated with mood in the bulimic group, but not in controls. In addition, the glucose injection induced a heightened urge to binge in the bulimic group (compared to placebo at 10 and 60 min), whereas reducing food cravings (for sweets) in the controls (at 5 min). When collapsed across time and injection condition, the blood glucose level of bulimics was lower than that of controls. There were no differences in insulin response between the groups. The bulimic group was found to have lower baseline levels of blood tryptophan, whereas no differences in the tryptophan/LNAA ratio were observed either at baseline or following glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Desipramine and fenfluramine were administered to bulimic patients in a 15-week study of double-blind, placebo-controlled, crossover design. The 22 patients in the study met DSM-III criteria for bulimia and were of normal weight. Twelve subjects were randomly allocated to the fenfluramine group, and 10 subjects received desipramine. Half the subjects in each group received the active drug in the first 6 weeks and half received placebo. There was a 3-week washout period, after which subjects were crossed over for the remaining 6 weeks. The Eating Disorder Inventory, profile of Mood States, bulimia symptom checklists, and Hopkins Symptom Checklist were administered at weeks 0, 2, 4, 6, 9, 11, 13, and 15. Subjects maintained a daily record of bingeing, vomiting, and laxative/diuretic abuse. Results indicated that both drugs had beneficial effects on bingeing and vomiting frequency, although a greater proportion of patients were identified who responded to fenfluramine than to desipramine. Fenfluramine and desipramine were also effective in reducing the psychological symptoms of bulimia, such as the urge to binge, and feelings of depression. Results suggest that direct alteration of central food intake regulatory centers can effectively control bulimia