Hypothalamic modulation of growth hormone secretion in the rhesus monkey: evidence from intracerebroventricular infusions of glucose, free fatty acid, and ketone bodies.
To evaluate the hypothalamus as a possible site of metabolic modulation of GH secretion, we studied the GH response to insulin hypoglycemia (IHG) and nicotinic acid (NA)-induced FFA depression in the absence and presence of third ventricular (ivt) infusions of glucose, oleic acid (Ol-Ac), or beta-hydroxybutyrate (beta OHB). Four rhesus monkeys had been prepared for chronic remote iv and ivt infusions as well as blood sampling from the adjacent room. Statistical evaluation used a two-way analysis of variance and individual comparisons with Tukey's Studentized range test. The GH response (area under the curve +/- SE) to IHG was significantly reduced by a concomitant ivt glucose infusion (control, 1.0 +/- 0.1; IHG, 12.1 +/- 3.3; IHG plus ivt glucose, 7.0 +/- 1.2 microgram/L.120 min). The GH response to FFA depression was significantly reduced by ivt Ol-Ac or beta OHB infusion (control, 6.0 +/- 1.0; NA, 51.5 +/- 4.1; Na plus Ol-Ac, 81.2 +/- 1.3; NA plus beta OHB, 38.6 +/- 3.5 microgram/L.300 min). Introcerebroventricular infusions of glucose, Ol-Ac, or beta OHB alone had no effect on plasma GH, glucose, FFA, or beta OHB concentrations. These results provide evidence for a hypothalamic site of metabolic modulation of GH secretion in the rhesus monkey. This does not exclude an additional effect directly at the pituitary gland.
Quabbe
H J
HJ
Department of Internal Medicine, Klinikum Steglitz, Freie Universität, Berlin, Germany.
Bumke-Vogt
C
C
Iglesias-Rozas
J R
JR
Freitag
S
S
Breitinger
N
N
D000818:Animals; D005230:Fatty Acids, Nonesterified / Q000008:administration & dosage / Q000494:pharmacology*; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood*; D006854:Hydrocortisone / Q000097:blood; D006885:Hydroxybutyrates / Q000008:administration & dosage / Q000494:pharmacology; D007031:Hypothalamus / Q000502:physiology*; D007276:Injections, Intraventricular; D007328:Insulin / Q000097:blood; D007657:Ketone Bodies / Q000008:administration & dosage / Q000494:pharmacology*; D008253:Macaca mulatta; D008297:Male; D009539:Nicotinic Acids / Q000494:pharmacology; D009829:Oleic Acids / Q000008:administration & dosage / Q000494:pharmacology
D005230:Fatty Acids, Nonesterified; D006885:Hydroxybutyrates; D007328:Insulin; D007657:Ketone Bodies; D009539:Nicotinic Acids; D009829:Oleic Acids; D013006:Growth Hormone; D005947:Glucose; D006854:Hydrocortisone