Use of orchiectomy and testosterone replacement to explore meal number-to-meal size relationship in male rats

Because food intake is a function of meal number and meal size and because gender-related hormones are involved in feeding regulation, we explored effects of orchiectomy and testosterone replacement on the relationship between meal number and size and changes in resulting feeding patterns in adult male rats, randomized into orchiectomy and sham-operation groups. A rat eater meter measured feeding indexes for 1 wk before and 2 wk after castration and during 8 days of testosterone replacement. Orchiectomy leads to an immediate change in the meal number-to-size relationship, resulting in 1) change in pattern of feeding; 2) a significant decrease in dark-phase meal number; 3) a significant increase in dark-phase meal size, but insufficient to offset decrease in meal number, so total food intake significantly decreased during dark phase; 4) no significant change in light-phase meal number; and 5) an increase in meal size leading to an increased food intake during light phase, which offset decreased food intake in dark cycle and resulted in no net significant change in food intake after orchiectomy. Testosterone replacement acutely reversed effects of orchiectomy on meal number-to-meal size relationship, restoring feeding pattern. Data suggest that androgens immediately influence the meal number-to-meal size relationship. The speed of onset seen after orchiectomy suggests that the influence of testosterone on food intake may also occur partially via a nongenomic effect.

[1]  Paul Greengard,et al.  DARPP-32: Regulator of the Efficacy of Dopaminergic Neurotransmission , 1998 .

[2]  A. Laviano,et al.  The Brain's Normal Function , 1998, Science.

[3]  M. Smith,et al.  Leptin inhibits hypothalamic neurons by activation of ATP-sensitive potassium channels , 1997, Nature.

[4]  A. Laviano,et al.  Meal size and number: relationship to dopamine levels in the ventromedial hypothalamic nucleus. , 1997, The American journal of physiology.

[5]  M. Meguid,et al.  Eating‐associated VMN‐dopamine levels of rats: comparison of oral and intragastric feeding , 1997, Neuroreport.

[6]  R. Palmiter,et al.  Sensitivity to leptin and susceptibility to seizures of mice lacking neuropeptide Y , 1996, Nature.

[7]  M. Selmanoff,et al.  Prolactin- and testosterone-induced inhibition of LH secretion after orchidectomy: role of catecholaminergic neurones terminating in the diagonal band of Broca, medial preoptic nucleus and median eminence. , 1996, The Journal of endocrinology.

[8]  A. Laviano,et al.  Eating-related increase of dopamine concentration in the LHA with oronasal stimulation. , 1996, The American journal of physiology.

[9]  J. Gleason,et al.  The gut-brain brain-gut axis in anorexia: toward an understanding of food intake regulation. , 1996, Nutrition.

[10]  M. Meguid,et al.  Eating induced rise in LHA-dopamine correlates with meal size in normal and bulbectomized rats , 1995, Brain Research Bulletin.

[11]  E. Browne,et al.  The effect of discontinuing dehydroepiandrosterone supplementation on Zucker rat food intake and hypothalamic neurotransmitters. , 1995, International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity.

[12]  J. Panksepp.  Hypothalamic regulation of energy balance and feeding behavior. 1974. , 1995, Nutrition.

[13]  Y. Sakuma,et al.  Dihydrotestosterone-sensitive neurons in the male rat ventromedial hypothalamus , 1994, Brain Research Bulletin.

[14]  J. Blank,et al.  Role of Gonadal Steroids and Inhibitory Photoperiod in Regulating Body Weight and Food Intake in Deer Mice (Peromyscus maniculatus) , 1994, Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine.

[15]  J. Gleason,et al.  Olfactory bulbectomy in rats modulates feeding pattern but not total food intake , 1993, Physiology & Behavior.

[16]  S. Nicolaidis,et al.  Spontaneous feeding-related monoaminergic changes in the rostromedial hypothalamus revealed by microdialysis , 1992, Physiology & Behavior.

[17]  C. Plata-salamán,et al.  Interleukin-1β depresses calcium currents in CA1 hippocampal neurons at pathophysiological concentrations , 1992, Brain Research Bulletin.

[18]  R. Melcangi,et al.  The 5 alpha-reductase in the brain: molecular aspects and relation to brain function. , 1992, Frontiers in neuroendocrinology.

[19]  S. Kalra,et al.  A selective sexually dimorphic response in the median eminence neuropeptide Y , 1992, Brain Research.

[20]  R. Bellantone,et al.  Change in meal size, number and duration after neural isolation of liver and with TPN , 1991, Physiology & Behavior.

[21]  W. J. Mueller,et al.  Automated computerized rat eater meter: Description and application , 1990, Physiology & Behavior.

[22]  S. Kalra,et al.  Functional heterogeneity in neuropeptide-Y-producing cells in the rat brain as revealed by testosterone action. , 1990, Endocrinology.

[23]  B. Hoebel,et al.  Microdialysis Studies of Brain Norepinephrine, Serotonin, and Dopamine Release During Ingestive Behavior Theoretical and Clinical Implications a , 1989, Annals of the New York Academy of Sciences.

[24]  P. C. Butera,et al.  Central implants of diluted estradiol: independent effects on ingestive and reproductive behaviors of ovariectomized rats , 1989, Brain Research.

[25]  B. Hoebel,et al.  Feeding increases extracellular serotonin in the lateral hypothalamus of the rat as measured by microdialysis , 1989, Brain Research.

[26]  S. Kalra,et al.  Testosterone raises neuropeptide-Y concentration in selected hypothalamic sites and in vitro release from the medial basal hypothalamus of castrated male rats. , 1989, Endocrinology.

[27]  A. Matsumoto,et al.  Male-female difference in synaptic organization of the ventromedial nucleus of the hypothalamus in the rat. , 1986, Neuroendocrinology.

[28]  K. Lookingland,et al.  Comparison of the effects of castration and steroid replacement on incertohypothalamic dopaminergic neurons in male and female rats. , 1986, Neuroendocrinology.

[29]  C. Roselli,et al.  Regulation of brain aromatase activity in rats. , 1984, Endocrinology.

[30]  G. Wade,et al.  Testicular effects on food intake, body weight, and body composition in male hamsters , 1981, Physiology & Behavior.

[31]  A. Núñez,et al.  Central effects of testosterone on food intake in male rats , 1980, Physiology & Behavior.

[32]  M. Inaba,et al.  Effect of estradiol-17 beta and other steroids on noradrenaline and dopamine binding to synaptic membrane fragments of rat brain. , 1979, Journal of steroid biochemistry.

[33]  S. Petersen.  Effects of testosterone upon feeding in male mice , 1978, Animal Behaviour.

[34]  M. Sar,et al.  Distribution of androgen target cells in rat forebrain and pituitary after [3H]-dihydrotestosterone administration. , 1977, Journal of steroid biochemistry.

[35]  S. Petersen.  The temporal pattern of feeding over the oestrous cycle of the mouse , 1976, Animal Behaviour.

[36]  J. Blaustein,et al.  Ovarian influences on the meal patterns of female rats , 1976, Physiology & Behavior.

[37]  G. Wade,et al.  Androgenic control of food intake and body weight in male rats. , 1976, Journal of comparative and physiological psychology.

[38]  G. Wade.  Some effects of ovarian hormones on food intake and body weight in female rats. , 1975, Journal of comparative and physiological psychology.

[39]  J. Panksepp.  Hypothalamic regulation of energy balance and feeding behavior. , 1974, Federation proceedings.

[40]  W. Beatty,et al.  Suppression of feeding by intrahypothalamic implants of estradiol in male and female rats , 1974 .

[41]  H. Kissileff,et al.  Inhibitory controls of feeding by the ventromedial hypothalamus. , 1974, The American journal of physiology.

[42]  R. Moore,et al.  Loss of a circadian adrenal corticosterone rhythm following suprachiasmatic lesions in the rat. , 1972, Brain research.

[43]  E. Valenstein,et al.  Sex Differences in Body-Weight Change following Gonadectomy of Rats , 1968, Psychological reports.

[44]  Tetsuro Yamamoto,et al.  Reciprocal relationship of the lateral and ventromedial hypothalamus in the regulation of food intake , 1967 .

[45]  J. Brobeck,et al.  Hypothalamic Control of Food Intake in Rats and Cats * , 1951, The Yale journal of biology and medicine.