LHRH receptors and LHRH receptor-bearing cells in pituitaries of streptozocin diabetic male rats.
Streptozocin (STZ)-diabetic rats have low hypothalamic luteotropic hormone-releasing hormone (LHRH) secretion and various alterations of gonadotrope cells, among which low luteotropic hormone (LH) secretion. Possible causes for the gonadotrope disorders may be low hypothalamic LHRH secretion alone or combined with reduced (a) number of LHRH receptor sites, or (b) receptor to ligand affinity, or (c) of LHRH receptor-bearing cells. To clarify this question we determined by saturation and competition binding Bmax, KD and KA of the LHRH receptor sites and counted the receptor-bearing cells in pituitary glands of control and STZ-diabetic adult male rats. We found a single receptor class, the Bmax was strongly reduced in diabetic animals whereas both KD and KA were similar in the two groups. The number of LHRH receptor-bearing cells in diabetic animals was increased. Therefore a reduced number of receptor sites per gonadotrope cell occurs in our model. Since in the STZ-diabetic male rats the number of gonadotropes is increased, a higher number of receptor-bearing cells was observed. We conclude that the reduced LH secretion from the diabetic pituitary gland might be due to a reduced number of LHRH receptor sites in the pituitary gland. The increased number of receptor-bearing cells might partially compensate for this change.
Bestetti
G E
GE
Division of Experimental Pathology, University of Berne, Switzerland.
Barone
D
D
Walz
A
A
Moser
B
B
Boujon
C E
CE
Brändli-Baiocco
A
A
Rossi
G L
GL
D000818:Animals; D001710:Biotin; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000473:pathology; D006728:Hormones / Q000097:blood; D007150:Immunohistochemistry; D007328:Insulin / Q000097:blood; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009929:Organ Size / Q000502:physiology; D010902:Pituitary Gland / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011966:Receptors, LHRH / Q000378:metabolism*; D015430:Weight Gain / Q000502:physiology
D001786:Blood Glucose; D006728:Hormones; D007328:Insulin; D007457:Iodine Radioisotopes; D011966:Receptors, LHRH; D001710:Biotin