title: In vivo patterns of circulating steroids in adult male rats. IV. Evidence for rapid oscillations in testosterone in normal and totally parenterally nourished animals.
abstract: In vivo patterns of circulating testosterone (T) were investigated in stock fed controls and parenterally nourished (TPN) rats. Rats were sampled at 2 minute intervals for 30 minutes via a jugular cannula. Both groups exhibited a rapid oscillatory T pattern. In the control group, T concentrations at any specific time interval exhibited large differences with coefficients of variation (17-88%). In TPN rats this variation was 34-79%. Moreover, the mean T concentration of all samples obtained during the 30 minute period for each individual animal ranged from 1.3 +/- 0.1 (S.E.M.) to 3.5 +/- 0.3 (S.E.M.) ng/ml in controls and 1.3 +/- 0.1 (S.E.M.) to 2.0 +/- 0.2 (S.E.M.)ng/ml in controls and 1.3 +/- 0.1 (S.E.M.) to 2.0 +/- 0.2 (S.E.M.) ng/ml for TNP rats respectively. The mean coefficient of variation in control animals, however, was twice that of TPN rats, indicating that variation in basal T may be minimized during intravenous feeding. The occurrence of rapid oscillations in T  of both stock and parenterally fed animals shows that nutritional regimen does not affect this phenomenon.
mesh_terms: D000818:Animals; D002404:Catheterization; D008297:Male; D010288:Parenteral Nutrition; D010289:Parenteral Nutrition, Total; D051381:Rats / Q000097:blood*; D013739:Testosterone / Q000097:blood*; D013997:Time Factors
chemical_list: D013739:Testosterone