Bilateral distribution of aminopeptidase activities in selected structures of a photoneuroendocrine circuit and other rat brain areas.
Provided that soluble aminopeptidases, the most abundant proteolytic enzymes found in brain, are involved in the metabolism of several neuropeptides, their activity could be a reflect of neuropeptide function. Therefore, in order to analyze their rate of participation, we have measured 4 soluble aminopeptidase activities: leucine aminopeptidase, arginine aminopeptidase, aspartate aminopeptidase, and pyroglutamate aminopeptidase, using arylamide derivatives as substrates, in selected structures integrating the photoneuroendocrine circuit related to the melatonin rhythm generating system and other rat brain areas. The regional distribution of all the activities was heterogenous: a 3-fold (leucine-, arginine- and aspartate-aminopeptidase) and 5-fold (pyroglutamate aminopeptidase) difference was observed between the regions with the highest and lowest activity. Significant differences were displayed between the left and right retina for pyroglutamate aminopeptidase and arginine aminopeptidase activities. High levels of pyroglutamate aminopeptidase were evident in the retina and adenohypophysis, which is consistent with a role for thyrotropin releasing hormone in photoreceptive mechanisms, and support its well established role in controlling thyrotropin releasing hormone in anterior pituitary. The presence of a high activity rate of aspartate aminopeptidase in adenohypophysis implies an active participation of angiotensin peptides at this level.
Department of Physiology, Medical School, University of the Basque Country, Leioa/Spain.
M
M
Ramirez
B
B
Sanchez
G
G
Arechaga
S
S
Garcia
P
P
Lardelli
D
D
Venzon
J M
JM
de Gandarias
D000626:Aminopeptidases / Q000032:analysis*; D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000378:metabolism; D043384:Glutamyl Aminopeptidase; D007931:Leucyl Aminopeptidase / Q000032:analysis; D008297:Male; D009474:Neurons / Q000201:enzymology*; D009479:Neuropeptides / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000201:enzymology*; D011751:Pyroglutamyl-Peptidase I / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000201:enzymology*; D013973:Thyrotropin-Releasing Hormone / Q000502:physiology
D009479:Neuropeptides; D013973:Thyrotropin-Releasing Hormone; D000626:Aminopeptidases; D007931:Leucyl Aminopeptidase; C019721:aminopeptidase B; D043384:Glutamyl Aminopeptidase; D011751:Pyroglutamyl-Peptidase I