The role of the splenic pancreatic lobe in regulating metabolic normalcy following 99% pancreatectomy in chickens.
The functional competency of the splenic pancreatic lobe of adult chickens was evaluated by studying plasma and tissue levels of insulin (IRI), glucagon (IRG), somatostatin (IRSRIF), and avian pancreatic polypeptide (IRAPP) for 16 days following surgical removal of 99% of the pancreas. The rationale underlying this approach was to assess whether the splenic remnant tissue after 99% pancreatectomy was capable of maintaining apparent metabolic normalcy as has been suggested in the literature. Partial (99%) pancreatectomy resulted in almost immediate enlargement of the splenic remnant, immediate decreases in both plasma IRI and IRAPP, both of which subsequently reattained normal levels (IRI in 4 days and IRAPP in 16 days). Hyperinsulinemia persisted from Days 4-7 and then returned to normal the remaining 9 days. Plasma IRG levels increased markedly and progressively for the entire 16-day observation period. Plasma I/G molar ratios indicated a strong catabolic trend in the 99% depancreatized group approaching values of 0.4 by 4 hr postop, returning to normal by Day 5, only to decrease progressively again into another sustained catabolic mode of 0.8 or less for the additional 11 days. Splenic lobe hormone (total) content of IRI, IRG, and IRAPP increased significantly throughout the 16-day observation period; however, parenchymal enlargement of nonendocrine lobe tissue was so great that actual concentrations of IRI and IRG decreased significantly while IRAPP concentration appeared to remain constant at control levels. IRSRIF levels were very sensitive both to pancreatectomy (increasing 140% 16 days later) and to fasting (decreasing 52% after 48 hr). IRG levels increase with fasting and with the exception of IRAPP, pancreatectomy appeared to increase the "sensitivity" of the splenic remnant in responding to the fasting stimulus. The results suggest that very rapid enlargement of the remnant splenic lobe following 99% pancreatectomy is probably adequate to maintain an apparent metabolic normalcy in adult chickens. The depancreatized animal enters a strongly catabolic mode, due mainly to hyperglucagonemia, even though food intake is normal and body weight is constant (though at subcontrol levels) after 16 days. There is no evidence to support the suggestion that SRIF stimulates glucagon release.
Cieslak
S R
SR
Hazelwood
R L
RL
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002645:Chickens / Q000378:metabolism / Q000502:physiology*; D005215:Fasting; D005260:Female; D005934:Glucagon / Q000097:blood / Q000378:metabolism; D007328:Insulin / Q000097:blood / Q000378:metabolism; D010179:Pancreas / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology*; D010180:Pancreatectomy; D010187:Pancreatic Hormones / Q000097:blood* / Q000378:metabolism; D010191:Pancreatic Polypeptide / Q000097:blood / Q000378:metabolism; D013004:Somatostatin / Q000097:blood; D013154:Spleen
D001786:Blood Glucose; D007328:Insulin; D010187:Pancreatic Hormones; D013004:Somatostatin; C009725:pancreatic polypeptide, avian; D010191:Pancreatic Polypeptide; D005934:Glucagon