Prefeeding enables the expression of neuromedin B-anorexia in both real and sham feeding rats

Prefeeding enables the expression of neuromedin B-anorexia in both real and sham feeding rats

86 ABSTRACTS Pallidal Neurons Monitor Both the Internal and External Milieux. Z. KARADI, L. LI~NARD, B. FALUDI and A. CZURKO. P~cs University, Medic...

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ABSTRACTS

Pallidal Neurons Monitor Both the Internal and External Milieux. Z. KARADI, L. LI~NARD, B. FALUDI and A. CZURKO. P~cs University, Medical School, Institute of Physiology, H-7643 P~cs, Hungary. To verify our hypothesis on complex regulatory functions of pallidal glucose-sensitive (GS) cells, extracellular single neuron activity was recorded in the globus pallidus (GP) rhesus monkeys during: (1) microelectrophoretic administration of chemicals (glucose, glutamate, catecholamines, Ach, GABA, etc.), (2) gustatory and (3) olfactory stimulations. The overall proportion of GS neurons was 17% in the primate GP. Gustatory and olfactory units (14% and 7%, respectively) formed a well localized population of pallidal neurons in the ventralmedial region of the structure. The GS cells proved to be especially very likely to change in firing rate in response to tastes and smells: more than two-thirds of the chemosensitive neurons responded to exogenous chemosensory stimuli. While displaying heterogeneous activity changes to microiontophoretically applied neurotransmitters in general, the GS taste- and smellresponsive cells showed distinct dopamine and norepinephrine sensitivities compared to the glucose-insensitive, non-chemosensory units. Our present findings, along with previous data from the lateral hypothalamic area and amygdaloid body, demonstrate a substantial overlap of the central gustatory representations and the hierarchically organized glucose-monitoring neural network. Constituents of these complex systems, the cbemosensitive neurons, appear to possess integrative roles in the central feeding control. [Sponsored by the Hungarian National Research Fund (T 1404/1990 and E 012296/1993; L.L. and T 013307/1994; Z.K.).]

Prefeeding Enables the Expression of Neuromedin B-anorexia in Both Real and Sham Feeding Rats. T. C. KIRKHAM and J. GIBBS. Bourne Laboratory, The New York Hospital-Cornell Medical Center, White Plains, NY 10605, U.S.A. Bombesin's satiety action is mediated by receptors for its mammalian analogues, gastrinreleasing peptide (GRP) and neuromedin B (NMB). GRP reliably suppresses eating; NMB typically has little effect. We report here a potent anorectic action of NMB. Non-deprived rats were given 30-min (prefeed) access to a liquid diet, injected i.p. with saline or NMB (8-64 Ixg/kg), then given a further 60 min access to the diet. NMB dose-relatedly suppressed intake from the beginning of the test. The importance of the prefeed to NMB's action was examined in animals with gastric fistulae, trained to sham feed the liquid diet. Five minutes before presentation of the test diet, fistulae were opened, stomachs rinsed and NMB or vehicle injected. Without prefeeding, NMB (16-64 ~tg/kg) failed to significantly suppress sham intake. When rats were allowed to real feed for 30 min before the sham feeding test, NMB exerted a marked anorectic action, similar to that seen in prefed intact rats. These results support a role of NMB in the control of postprandial satiety.

Spontaneous Meal Size is Increased by Hepatic Portal Infusion of insulin Antibodies, but Unaffected by Insulin Infusion. W. LANGHANS, D. SURINA and N. GEARY.* Institute for Animal Sciences, Swiss Federal Institute of Technology, 8092 Zurich, Switzerland, and *Bourne Laboratory, New York HospitaI-Cornell Medical Center, White Plains, NY 10605, U.S.A. Substantial evidence indicates that csf insulin level is a signal contributing to the lipostatic control of food intake. But whether prandial release of pancreatic insulin controls the size of individual meals remains unclear. To investigate this, ad libitum-fed rats received remotelycontrolled hepatic portal infusions (3 min, 0-033 ml/min) of insulin and insulin antibodies