Studies on the effects of low doses of 5 alpha-dihydrotestosterone (DHT) on the basal levels of serum gonadotropins and the sensitivity of the pituitary to luteinizing hormone releasing hormone (LHRH) in adult male rats

Investigations were undertaken to study the effect of administering s.c. 10, 25, 50, 100, 500 and 1000 ng DHT/rat/day to normal adult male rats, for six weeks, on the basal levels of serum gonadotropin and the sensitivity of the pituitary to LHRH. The control group received olive oil. Animals were weighed and bled via cardiac puncture before the beginning of the treatment and weekly thereafter. After the last bleeding rats were injected intracardially 200 ng LHRH/rat and killed 15 min later. Blood, pituitary and testes were collected. Data were analyzed with respect to the control group and with respect to day zero of the treatment. DHT failed to produce a persistent effect on the serum gonadotropin. 10 and 500 ng DHT suppressed FSH levels significantly on days 21 and 7, respectively. 25, 50, 100 and 1000 ng DHT stimulated the release of FSH on day 42. 10 ng DHT reduced the levels of LH on day 14 of the treatment. 10, 25 and 50 ng DHT increased the sensitivity of the pituitary to release more LH in response to LHRH while 100, 500, 1000 ng DHT inhibited LHRH induced release of FSH. DHT at all doses tested failed to affect intrapituitary levels of LH and FSH. 10, 500 and 1000 ng DHT reduced the weights of the pituitaries as compared to the control group. The data demonstrate effects of DHT which are transient on the basal release of gonadotropins but are more persistent and differential on the sensitivity of the pituitary to LHRH.     

Acidic metabolites of benzyl alcohol in greenbug resistant barley

(¹⁴C-Carbinol)benzyl alcohol taken up through the roots of greenbug (Schizaphis graminum) resistant barley is metabolized into a large number of radioactive compounds which have been separated by ion exchange chromatography. Two of these acidic metabolites have been identified as O-benzoyl-l-malic acid and N-benzoylaspartic acid; these identifications were confirmed by synthesis.     

Polymorphic serum prealbumin (Pa) of pig, identified as an a!-protease inhibitor

Pig serum proteins were analysed by horizontal polyacrylamide gel electrophoresis, with a discontinuous buffer system (pH 9.0). A 12 % acrylamide concentration in the separation gel was used. Each of the two prealbumin (Pa) alleles gave rise to two closely migrating fractions. The polymorhic Pa was identified as an a,-protease inhibitor as the Pa fractions inhibited the esterolytic activity of both bovine trypsin and chymotrypsin. Therefore, it has been proposed that the locus symbol for this prealbumin be changed to Pi-1. The protease inhibitory spectra and electrophoretic mobility of the Pa (Pi-1) fractions suggested that this protein was probably the same as the pig serum a,-protease inhibitor described in some earlier studies and that it corresponds to human serum a,-protease inhibitor (Pi).     

Pig plasma postalbumin-2 (alpha 1B-glycoprotein): isolation, partial characterization and immunological cross-reactivity with other mammalian sera

1. Components of pig plasma postalbumin-2 (PO2) protein, after rivanol-ammonium sulphate fractionation of plasma, were separated from other proteins by an easy and rapid method of horizontal double-one dimensional IPG-PAGE. The protein was recovered from polyacrylamide gel by combination of electrophoresis and isoelectric focusing. 2. The mol. wt of PO2 was estimated to be 68,000, using SDS-PAGE. 3. Amino acid and carbohydrate compositions of PO2 were very similar to those of human plasma alpha 1B-glycoprotein (alpha 1B), confirming that PO2 is the porcine homologue of human alpha 1B. 4. Neuraminidase treatment resulted in a decrease of electrophoretic migration velocity of all four studied components of PO2. 5. Homologous proteins to pig PO2 (alpha 1B) were observed, not only in human plasma but also in plasma of dog, horse and rabbit, by immunoblotting.     

Changes in uterine phosphatase levels in mice deprived of LH during early pregnancy.

Mice injected with normal rabbit serum on Day 4 of gestation showed a progressive increase in specific alkaline and acid phosphatase activities on Days 6 and 7. Mice injected with antiserum to LH on Day 4 showed a significant decrease in specific alkaline phosphatase activity estimated biochemically on Days 6, 7 and 8, but this decrease was histochemically evident only on Day 8. Similarly, acid phosphatase activity in antiserum-treated mice was significantly increased on Days 6, 7 and 8 when estimated biochemically, but only on Day 8 when studied histochemically.     

Effect of castration and steroid treatment on the release of gonadotropins by the rat pituitary-hypothalamus complex in vitro

Comparative in vitro studies on the release of LH and FSH by pituitary-hypothalamus complex (PHC) with intact portal plexus and whole pituitary (PI) from adult male rats showed that PHC released LH at a greater rate and in larger amounts than PI. PHC and PI released FSH in comparable amounts and rates. Attempts were made to correlate serum gonadotropin levels to that released by PHC and PI at 1, 3, 7, 14, 21 and 46 days of post-castration (PC). Sham operated animals served as controls. Castration increased serum LH and FSH levels but in different profiles. CPHC and CPI (PHC and PI from castrated rats) released less LH than NPHC and NPI (PHC and PI from sham operated controls) till day 14 PC after which CPHC and CPI released more LH than NPHC and NPI respectively. Castration abolished the intrinsic capacity of PHC to secrete more LH than PI. CPHC and CPI secreted significantly less FSH than NPHC and NPI at 1, 3 and 7 days PC. At days 14 and 21 of post-castration PCNCP or CPI and NPHC or NPI released similar amounts of FSH. Administration of 5 alpha-dihydrotestosterone (DHT, 1 mg/rat/day) or estradiol valerate (EV, 1 microgram/rat/day) immediately following castration prevented the rise in serum LH and FSH but increased the amounts of LH and FSH released by CPHC and CPI. The treatment caused a marked stimulation of FSH released by CPI.(ABSTRACT TRUNCATED AT 250 WORDS)