Brain indoleamines in alloxan- and streptozotocin-induced diabetic rats.
Previous work by other authors has shown that alloxan-induced diabetes increases whereas streptozotocin-induced diabetes does not alter nonesterified fatty acid (NEFA) plasma levels. The present study replicates these results and demonstrates that fasted, streptozotocin-induced diabetic animals also have increased NEFA levels. In addition, brain levels of 5-hydroxytryptamine (5-HT) and of its immediate precursor and metabolite were measured. Alloxan- and fasted, streptozotocin-induced diabetic rats showed significant increases in brain indoleamine concentrations, whereas fed, streptozotocin-induced diabetic rats had unchanged levels of the same compounds. Levels of brain indoleamines exhibited a strong positive correlation with wet-dog shakes (an index of 5-HT activity) elicited by hippocampal stimulation. Blockade of wet-dog shakes by 5-HT receptor antagonists strengthens the proposal that this behavior is a good index of central 5-HT activity. The increased content of brain indoleamines in alloxan- and fasted, streptozotocin-induced diabetic rats may be related to the increased NEFA plasma levels seen in the same animals. This hypothesis is supported by the positive correlation demonstrated between NEFA and 5-HT levels. In conclusion, it is suggested that alloxan-induced diabetes may represent a useful model for studying the various behavioral changes known to occur in diabetics.
Mello
L E
LE
Departamento de Neurologia e Neurocirurgia, Escola Paulista de Medicina, São Paulo, Brazil.
Bortolotto
Z A
ZA
Cavalheiro
E A
EA
D000496:Alloxan; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001786:Blood Glucose / Q000032:analysis; D001921:Brain / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000523:psychology; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D007211:Indoles / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013311:Streptozocin
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007211:Indoles; D013311:Streptozocin; D000496:Alloxan