Stimulation of a bulbospinal 5-HT pathway in the rat brain produces hyperglycaemia.
The glucoregulatory role of spinally projecting serotonin (5-HT) neurones near the ventrolateral surface of the medulla oblongata was investigated by stimulating these nerve cells in normal rats and in rats with selective chemical ablation of 5-HT nerves in the spinal cord. Electrical stimulation of the lateral medulla produced hyperglycaemia in normal rats; the increase in blood glucose was proportional to the intensity and frequency of stimulation. Furthermore, microinjection of kainic acid or L-glutamate at the same sites also produced hyperglycaemia. This stimulation-induced hyperglycaemia was significantly reduced by spinal transection or adrenalectomy. Selective destruction of spinal 5-HT nerves produced by intraspinal injection of 5,7-dihydroxytryptamine also reduced the magnitude of the hyperglycaemia response to electrical stimulation of the lateral medulla. This indicates that stimulation of 5-HT nerve cells adjacent to the ventrolateral surface of the medulla oblongata and projecting to the spinal cord increases the adrenal-sympathetic efferent activity and leads to hyperglycaemia in rats.
Shian
L R
LR
Department of Internal Medicine, National Defence Medical Centre, Taipei, Taiwan, Republic of China.
Lin
M T
MT
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000315:Adrenalectomy; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D004525:Efferent Pathways / Q000502:physiology; D004558:Electric Stimulation; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D007608:Kainic Acid / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000502:physiology*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology* / Q000601:surgery
D001786:Blood Glucose; D005971:Glutamates; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D018698:Glutamic Acid; D007608:Kainic Acid