Hypothalamie Hyperphagia and Social Interaction in the Monkey

C. L. Hamilton Veterans Administration Hospital,

Coatesville, Pa.

By

and J. R. Brobeek University of Pennsylvania,

Philadelphia, Pa.

Bilateral destruction in the region of the ventromedial nuclei of the hypo- thalamus in the monkey is followed by a significant increase in food intake. The present work investigated the effects of such lesions on the dominance hierarchy in a group of monkeys.

The subjects were six rhesus monkeys (two females) weighing approxi- mately 4 kg. at the beginning of the study. The dominance hierarchy was determined on two tests. The first was competition between two animals for one piece of food. The second, avoidance of shock, was conducted in a typical shock box. For this test the animals were individually conditioned to grasp and hang on a bar, projected into the box at the sound of a tone (conditional stimulus), to avoid electric shock to the feet. All animals were given ten trials a day until a criterion of 100 per cent conditioned responses for two consecutive days had been established. Two animals were then placed in the box and tested under the above conditions. Since the bar was large enough for only one animal, those not getting the bar had to remain on the grid for two seconds of shock. At the end of the two second shock period the bar was removed and the animal dropped on the grid, setting up the next trial. I n both tests ten trials a day were conducted and all combina- tions of animals observed. Dominance was defined in terms of the number of pieces of foot obtained and number of times on the bar.

After replication of both procedures bilateral electrolytic lesions were stereotaxically placed in the region of the ventromedial nuclei of the hypo- thalamus of the most submissive animal. Ten days postoperatively the food tests were run followed by the avoidance. The next two submissive animals were then operated upon and tested in a similar sequence.

Preoperative dominance ranks on the food and avoidance scales were identical. The mean weight gain for the operated animals the first five weeks postoperative was 2.6 kg. compared to a mean weight gain over the pre- ceding year of 1.9 kg. All three operated subiects showed an increase in food dominance rank with no change on the avoidance test. One animal changed from most submissive to most dominant and the other two (females) moved up one increment. These postoperative changes were accompanied by a two- three hundred per cent increase in spontaneous food intake.

Acta Neurovegetativa, Bd. XXIV, Heft 1--4. 35

546 Diskussion

The results indicate that in the monkey, hypothalamic hyperphagia is ac- companied by increased aggressiveness, but only with respect to food gathering behavior.

(This study was supported by Grant, M 8827 USPHS.)

Diskussion

Prof. Dr. F. Feyrter (Wien)! Die Entartung des braunen Fettgewebes beim Phaeochromozytom.

Das mensehliche Fettgewebe l~iBt w~hrend der f6talen Entwieklung 2 Arten unterseheiden: 1. Das vulg~ire univakuol~ire Fettgewebe des Panniculus adiposus mit Siegelringzellen. 2. Das braune plurivakuol~e Fettgewebe im Irmeren des K~rpers mit maulbeeff6rmigen Zellen. Beim Erwachsenen lassen sieh die beiden Arten unter normalen Verh~iltnissen nicht mehr unterseheiden; auch die Elemente des braunen Fettgewebes zeigen sodann die Form von Siegelringzellen. Unter pathischen Verh~iltnissen l~il3t das braune Fettgewebe jedoch die Maske der Gleich- artigkeit mit dem vulg~iren Fettgewebe fallen. Eines der eindrueksvollsten Bei- spiele hierfiir ist die Umwandlung der univakuol~iren Zetlen des reffen braunen Fettgewebes beim Phaeochromozytom des Nebennierenmarkes in plurivakuol~e Elemente sowie in Elemente mit kSrnig-tropfigem Zytoplasma yon lipoidiger und lipoproteidiger Beschaffenheit. Dieses in solehen Fiillen regelm~il3ig zu beobaeh- tende Syndrom l~il3t vom Pathischen her auf die Norm sehlieBen in dem Sinne, dab das Stoffwechselgeschehen im braunen Fettgewebe humoral-neural yon seiten des Nebennierenmarkes gesteuert wird. Die Anregung zur experimentellen Erfor- schung des Gegenstandes ergibt sich dureh den besagten Befund von selbst.