No abstract

Lesions of the rhinencephalon, primarily restricted to the pyriform lobe and amygdaloid complex, modifies the eating behavior of cats so that their food intakes and body weights are significantly increased. Neodecortication has no significant effect on either food intake or body weight whether done before or after the amygdalectomy. The amygdaloid cats eat significantly more than their controls and gain weight at a significantly more rapid rate when on an ad libitum feeding regimen. It is concluded that the amygdaloid complex constitutes some type of feeding center in the cat probably exerting its effects on more primitive lower brain stem feeding mechanisms.

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Stereotaxic lesions in the lateral hypothalamus of the cat at the level of the tuberal region were found not to alter food intake or body weight from preoperative control levels whereas lesions restricted to the ventromedial nuclei produced hyperphagia and obesity. Cats with combined lateral and ventromedial lesions showed no changes in food intake or body weight. Cats with combined amygdalar, lateral and ventromedial lesions developed hyperphagia and obesity but the rates of weight gain were about three times faster than occurred with amygdalectomy alone. Food intake in this group after operation more than doubled preoperative levels and the gain in weight of the group during the dynamic phase of obesity amounted to 23.6% as compared to 2.3% for normal and sham-operated controls. It is concluded that the lateral hypothalamus does not function as a ‘feeding’ center in the cat but that the ventromedial nucleus is probably a ‘satiety’ center. Furthermore it is probable that inhibitory amygdalar effects on food intake do not operate through the middle hypothalamus since hyperphagia and obesity results following destruction of the entire middle hypothalamus and amygdalae.

It has been known for some time that the skeletal muscle of frogs when sensitized by a suitable dye contracts when exposed to visible light of sufficient intensity, although a contracture with long latent period, rather than the characteristic twitch and tetanus of normal stimulation, has been the usual result. Lippay ('29) demonstrated that the effective radiation was in the region of the absorption spectrum of the dye used, and this rule holds also for other types of photodynamic phenomena (Blum, '32). Usually the presence of free oxygen has been found necessary for the production of photodynamic effects (Blum, '32) ; Lippay ( '30) and Spealman and Blum ('33) have found this to be true for the photostimulation of muscle. Some years ago Hinrichs and Lillie ('24) showed that the response of eosin-stained muscle to light was greatly increased when the tissue was immersed for a few minutes in pure isotonic solutions of sodium Salts with a deionizing influence on calcium (such as Natartrate and citrate) were found especially effective ; but the direct stimulating effect of the light was obscured by that of the salts which themselves cause vigorous twitching and tetanus, so that satisfactory quantitative relations could not be obtained. I n the present investigation a further experimental study has been made of the photosensitivity of stained This work was mpported in part by a graut from the Rockefeller Foundation. a