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Biomedical subjects

C A Opsahl

Publications and source records attributed to C A Opsahl.

5 recordsLinked to original sources

Afferent projections related to attack sites in the ventral midbrain tegmentum of the cat.

Quiet attack was elicited by electrical stimulation of the ventrolateral midbrain tegmentum of the cat. The paw was not used other than to position or hold the rat during the bite. Bites were directed toward the head and neck region and were not accompanied by autonomic responses other than pupillary dilation and sometimes slight piloerection on the back. Horseradish peroxidase was deposited at the attack sites. Cells labeled with the peroxidase reaction product were located in gyrus propreus, gyrus genualis, nucleus accumbens, bed nucleus of the stria terminalis, bed nucleus of the anterior commissure, nucleus of the diagonal band, substantia innominata, anterior amygdaloid area, ventromedial hypothalamic area, paraventricular nucleus, perifornical hypothalamic area, lateral hypothalamic area, dorsal hypothalamic area, field of Forel, midbrain reticular formation, superior colliculus, ventral central grey, lateral central gray, locus coeruleus, parabrachial nuclei, nucleus of the lateral lemniscus, oral pontine reticular nucleus, and the dorsal raphe. Other regions were less prominently labeled. Previous studies have shown most of these sites to have some involvement in attack.

Afferent Pathways↗

Body weight and gastric acid secretion in rats with subdiaphragmatic vagotomy and lateral hypothalamic lesions.

In an experiment to investigate the role of the vagus in the lateral hypothalamic (LH) syndrome of body weight loss, male albino rats were divided into four groups: (a) animals with bilateral LH lesions that were subsequently given a bilateral subdiaphragmatic vagotomy, (b) LH animals that received a control vagotomy operation, (c) nonlesion animals that were given a subdiaphragmatic vagotomy operation, (c) nonlesion animals that were given a subdiaphragmatic vagotomy, and (d) nonlesion animals that received a control vagotomy operation. Both LH lesions and vagotomy reduced body weight levels, though the effects differed in terms of the length of time required to reach initial maximal loss, the time required to reach chronic levels of maintenance, and the severity of body weight reduction. Fasting gastric acid secretion was lowered by LH lesions, and the extent of this reduction was positively correlated with the reduction in body weight. Finally, gastric contents after a 24-hr fast were greater in vagotomized rats than in nonvagotomized animals. These data are discussed in relation to the changes in gastric functioning after LH lesions and vagotomy.

Animals↗

Sympathetic nervous system involvement in the lateral hypothalamic lesion syndrome.

The role of the sympathetic nervous system in the lateral hypothalamic syndrome of body-weight loss was investigated. Bilateral electrolytic lesions of the lateral hypothalamus (LH) were performed in 90-day-old male albino rats. In experiment 1, the splanchnic nerves were resected at 35 days (right) and 70 days (left) postlesion. In experiment 2, bilateral adrenal demedullations were performed in a second group of rats with LH lesions (LH rats) at 35 days postlesion. The results indicated that lesions of the lateral hypothalamic area lowered body-weight maintenance levels to approximately 87% of nonlesion control values. Bilateral splanchnicetomy produced a significantly greater body-weight loss in nonlesion animals than in LH rats. Following adrenal demedullation, nonlesion rats also reduced body-weight levels whereas LH rats significantly increased weight-maintenance levels. In addition, the adrenal glands of LH rats with sham demedullations weighed significantly more than the adrenals of nonlesion-sham demedullated animals. These data are discussed in relation to metabolic-autonomic mechanisms that may play a role in LH lesion-induced weight loss.

Adrenal Medulla↗