The Effect of Electrical Stimulation of the Dorsal Raphe Nucleus on Local Cerebral Glucose Metabolism and Epileptogenesis in the Rat

<p>Anatomic connections between the dorsal raphé and the hippocampus have been described in the literature; however, the understanding of the functional importance of these connections is not complete. In these studies the "functional" raphé-hippocampal pathway was elucidated first by the 2-deoxy-d-glucose (2-DG) method, and second by the effect of dorsal raphé electrical stimulation on kindled seizure in the rat. In the 2-DG study, differences in local rates of cerebral glucose metabolism were quantified. The pattern of 2-DG uptake differed significantly from controls (animals with electrodes placed and not receiving an electrical stimulus) and subjects stimulated in the pontine oral reticular formation. The dorsal hippocampus CA_1&2 responded with an increase over control values of 87%, dorsal hippocampus CA_3&4 of 68%, the dentate gyrus of 83%, ventral hippocampus: CA_1&2 of 71% and CA_3&4 of 67% (<em>p</em> ≤ 0.01). This study thus showed that the dorsal hippocampus responds to dorsal raphé stimulation more readily than the ventral hippocampus, and that the lacunosum-moleculare layer of the dorsal hippocampus had a significant increase in metabolic rate following dorsal raphé electrical stimulation.</p> <p>Among extrahippocampal structures, the nucleus accumbens had the highest value for glucose uptake during dorsal raphé stimulation, an increase over controls of 118%. Other structures showing marked increase in glucose metabolism were: the medial forebrain bundle(MFB) = 68%, the cingulate bundle = 54%, the lateral septal nucleus = 41%, the diagonal band of Broca = 31%, the reticular thalamic nucleus = 49%, and the dorsal medial amygdaloid nucleus = 23% (<em>p</em> ≤ 0.01). pontine oral reticular formation (PORF) 2-DG uptake patterns were markedly different from dorsal raphé stimulated and control animals.</p> <p>Kindled animals also exhibited specific changes in various seizure indices that are related to the efficacy of seizure inhibition. Hippocampal kindled animals revealed an increase in afterdischarge threshold, a decrease in seizure severity, a decrease in seizure duration, and a greater number of stimulations required to generate afterdischarges. Dorsal raphé-stimulated-amygdala-kindled animals showed similar changes in seizure indices from control animals but the inhibitory effect was not as great as the dorsal raphé effect on hippocampal-kindled seizures. Moreover, dorsal raphé electrical stimulation generally decreased the postictal period of behavioral depression.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physiology

Year

1992

Author dc:creator

• Douglas, Clifford C.

Contributors dc:contributor

• George Maeda
• Robert F. Ackermann
• John Leonora
• John W. Patrickson
• Shokei Yamada

• Endocrinology, Diabetes, and Metabolism
• Physiology
• Raphé Nuclei -- physiology; Electric Stimulation; Hippocampus -- physiology; Glucose -- metabolism; Epilepsy -- etiology

Statement dc:rights

• This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Language dc:language

English

Repository record dc:identifier

https://scholarsrepository.llu.edu/etd/1538

OAI identifier oai:identifier

oai:scholarsrepository.llu.edu:etd-2315