Localization and actions of cholecystokinin in the rat pituitary neurointermediate lobe.
Rat pituitary neural lobe contained high concentrations of cholecystokinin-like immunoreactivity (CCK-LI). Section of the pituitary stalk resulted in loss of CCK-LI, and both lactation and replacement of drinking water with 2% saline resulted in marked depletion of CCK-LI. Rats with congenital diabetes insipidus (Brattleboro strain) had a 73% reduction in CCK-LI below the levels of hooded Long-Evans controls, where as levels in the brain were unchanged. Release of CCK-LI, labeled dopamine, and gamma-amino butyric acid in response to potassium depolarization was studied. There was a low fractional release of CCK-LI. Addition of sulfated CCK-8 (CCK-8s) to the medium enhanced the calcium-dependent potassium-stimulated release of dopamine, but basal release was unaffected. gamma-Amino butyric acid release was only poorly calcium dependent and not effected by extracellular CCK-8s. Vasopressin and oxytocin release were stimulated by electrical stimulation of the pituitary stalk, and were unaffected by the addition of CCK-8s to the medium. In vivo, however, the injection of 5 micrograms CCK-8s into the third ventricle resulted in increased plasma vasopressin concentrations.
D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D002766:Cholecystokinin / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D005260:Female; D008297:Male; D010121:Oxytocin / Q000378:metabolism; D010904:Pituitary Gland, Posterior / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D001127:Arginine Vasopressin; D010121:Oxytocin; D005680:gamma-Aminobutyric Acid; D002766:Cholecystokinin; D012844:Sincalide; D004298:Dopamine