Cerebrospinal fluid in the domestic fowl: composition and experimental studies

Cerebrospinal fluid (CSF) was obtained from anesthesized female white leghorn chickens by aspiration of the cisterna magna with a tuberculin syringe and 25 gauge needle. Chickens were grouped as six to ten weeks old, 11 to 18 weeks old and one to two years old. CSF was analyzed for total reducing substances (glucose), total protein, amino-nitrogen, sodium, potassium, chloride, pH and specific gravity. CSF glucose, protein and amino-nitrogen levels did not differ significantly in chickens ranging from six weeks to two years in age. CSF sodium and chloride levels were significantly lower in six to ten week old birds than in 11 week to two year old chickens while CSF potassium levels in six to ten week old chickens were significantly higher than in both older groups. Compared with mammals, chicken CSF contains an excess of glucose and protein, and a slight excess of chloride. Experimentally, a fall in chicken plasma and CSF glucose levels was observed following intravenous injections of beef insulin or sodium tolbutamide. Further, the administration of these substances directly into CSF resulted in a hypoglycemic reaction. Studies on bilateral vagotomized chickens indicate that the hypoglycemia observed following intracisternal injections of insulin is due to a stimulatory effect on specific parasympathetic "centers" concomitant with passage of this hormone from CSF into the bloodstream. Both insulin and tolbutamide, whether administered intravenously or intracisternally, were without effect on the glycogen levels of the avian glycogen body.