Cationic ferritin uptake by cultured anterior pituitary cells treated with the proteinase inhibitor, BOC-DPhe-Phe-Lys-H

Cultured cells from the anterior pituitary glands of adult rats were treated with the tripeptide aldehyde proteinase inhibitor, BOC-DPhe-Phe-Lys-H. The addition of this tripeptide aldehyde decreased the in vitro release of prolactin to 25% of the control value, while the release of growth hormone in the same cultures decreased to 33% of the control value. Prolactin immunostaining was stronger in semithin sections of proteinase-inhibitor-treated cultures than in control sections. After 2 h treatment with the inhibitor, prolactin- and growth hormone-containing secretory granules were numerous, and the number of crinophagic vacuoles had increased. In the presence of the inhibitor, the overall cytoarchitecture of parenchymal cells was well preserved, and the pathway of the uptake of cationic ferritin appeared to be unaffected.     

Effect of neonatal denervation on the distribution of fiber types in a mouse fast-twitch skeletal muscle

This study was designed to assess the changes in fiber-type distribution of the extensor digitorum longus (EDL) muscle of the mouse during the first 21 days of age following neonatal sciatic neurectomy. Denervated and normal muscles were compared at 7, 14, and 21 days of age and the normal EDL was also studied at 1 day of age. Frozen sections of the EDL were treated histochemically to detect NADH-tetrazolium reductase and myosin ATPase reactions. Quantitative assessment included measurements of cross-sectional areas and fiber counting. Denervation resulted in muscle atrophy which was due primarily to a decrease in individual fiber area as opposed to fiber loss. Histochemical maturation of the EDL was severely affected by neonatal denervation during the first three postnatal weeks. By 21 days, two extrafusal fiber types which were both oxidative could be distinguished. One type was highly atrophied and resembled an immature fiber exhibiting myosin ATPase staining at both acid and alkaline preincubation conditions, whereas another type was less atrophied and showed myosin ATPase staining resembling fast-twitch (type IIA) fibers. These findings emphasize the importance of an intact nerve supply in determining the phenotypic expression of skeletal muscle, and point to the early postnatal period as a critical stage in fiber type differentiation.     

Clomiphene citrate alters vaginal surface morphology in cycling rats.

Cycling virgin female rats were treated with clomiphene citrate (CC) during dioestrus of the reproductive cycle. Animals were sacrificed 2 days after the initial injection and their vaginal tissue was examined by scanning electron microscopy. Animals treated with one dose of CC had an epithelium consistent with a prolonged dioestrus. Treatment with CC for 2 days induced changes in the epithelium that had no resemblance to any normal hormonally controlled event in the vagina. It was found that CC had effects consistent with progesterone alone as well as effects unique to this superovulatory drug.