Biomedical subjects
B J Merry
Publications and source records attributed to B J Merry.
Effect of alpha, alpha, alpha-trifluoro-2-methyl-4'-nitro-m-lactotoluidide (Sch 16423) on serum testosterone and LH in rats.
Administration of Sch 16423 to intact male rats (5 mg/day s.c. for 7 days) resulted in a rapid and dramatic rise in the serum concentrations of LH and testosterone. This suggests that this metabolite of flutamide is the active antiandrogenic agent.
Dynamics of progesterone metabolism in the pseudopregnant rat.
The characteristics of the disappearance of progesterone and 20 alpha-dihydroprogesterone from blood were examined in rats made pseudopregnant by administration of gonadotrophins. Measurement of the disappearance of [3H]progesterone from blood indicated that progesterone metabolism can be represented by a two-compartment model in this animal preparation. The disappearance of [3H]progesterone from blood was described by two half-lives of 0.5 and 11.7 min. The metabolic clearance rate for this steroid was 2.9 litre/day, equivalent to a production rate of 3.9 mumol/day. The initial volume of distribution of the injected [3H]progesterone was 5.0 ml, a volume similar in size to the expected plasma volume. The total volume of distribution of [3H]progesterone (i.e. 'inner' and 'outer' pools) was in the range 24.8-35.4 ml. The disappearance of endogenous progesterone from the blood of pseudopregnant rats after vascular isolation of the ovaries showed two half-lives of 1.1 and 11.4 min respectively. The disappearance of a product of reductive metabolism of progesterone, 20 alpha-dihydroprogesterone, was apparently uniphasic, with a half-life of 41.3 min.
Influence of stress on the secretion of corticosterone in the duck (Anas platyrhynchos).
The influence of stress on the secretion of corticosterone has been investigated by radioimmunoassay in domestic ducks (Anas platyrhynchos) of 6-8 weeks of age. Intravenous and i.m. injections of synthetic ACTH (Synacthen, 25 i.u./bird and Synacthen Depot, 100 i.u./bird respectively) markedly increased (2.7- to 10-fold) basal concentrations of corticosterone in plasma (3-6 ng/ml) in comparison with those in birds injected with 0.9% saline (1 ml/bird). Maximum levels of 30-40 ng/ml plasma were reached after 30 min and 5 h respectivley. Increased levels of corticosterone in plasma were also seen within 5 min of i.v. administration of saline and remained as high as those in birds treated with Synacthen for at least 20 min after injection. Blood sampling (from the brachial vein) was, by itself, sufficient to increase levels of corticosterone in plasma; a large (twofold) rise being observed as soon as 1 min after initial handling and bleeding, with concentrations of 30-40 ng/ml being found in birds bled 15 times during a period of 14 min. However, in a flock of birds, the alarm created in unhandled birds while others were being bled had no effect on concentrations of corticosterone in plasma. Deprivation of food or water for 24 h also enhanced levels of corticosterone in plasma, as did 24 h of adaptation to 0.2 M-NaCl drinking water. These results have demonstrated the lability of the secretion of corticosterone in response to stress and demonstrated its usefulness as a physiological indicator of stress in ducks.
Onset of puberty and duration of fertility in rats fed a restricted diet.
Chronic dietary restriction such that the body weight of CFY Sprague-Dawley female rats was 50% that of animals fed ad libitum resulted in enhanced longevity (LD 50 of 1090 days compared to 704 days). All the experimental females had reached puberty by 227 days and 80% were able to conceive and wean young at 510 days, an age beyond that at which the control rats had ceased to breed (450 days). Some (25%) of the experimental rats were able to breed at over 800 days of age.
Luteolytic effects of prostaglandin F2alpha and 16-aryloxy-prostaglandin F2alpha in the hormonally induced pseudopregnant rat in vitro and in vivo [proceedings].
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Mitochondrial structure in the rat adrenal cortex.
Two distinct classes of mitochondria are described in the normal adrenal cortex of the Sprague Dawley CFY rat. Polyaminar mitochondria were frequently observed in the zona fasciculata and zona reticularis, particularly after ACTH stimulation of the cortex resulting from cold-stress exposure. It is uncertain whether such organelles are degenerating forms, or whether they have a specific functional role related to steroidogenesis in the normal cortical cell. In both normal and stressed adrenal cortices, protrusions of the outer membrane of mitochondria were evident, and were often seen penetrating lipid droplets. It is suggested that these protrusions may have some significance in the transport of cholesterol from the lipid droplet to the inner mitochondrial memrane 'desmolase complex', thus facilitating side-chain cleavage of cholesterol to pregnenolone.