Colocalization of prolactin and growth hormone within specific adenohypophyseal cells in male, female, and lactating female rats.

The localization of PRL and GH within adenohypophysial cells has been investigated with immunocytochemical methodology using colloidal gold of different sizes. Classically, using morphological criteria at the light and electron microscope levels, two types of individual cells have been described which, it is believed, exclusively produce either PRL or GH, i.e.

Effect of hypothalamic deafferentation on hypophysial and other endocrine gland blood flows.

The effects of partial or complete deafferentation of the medical basal hypothalamus (MBH) on blood flow through endocrine glands was evaluated using a modification of Sapirstein's indicator fractionation method. Adult female Wistar rats were distributed into three groups consisting of normal control animals (n = 12), animals in which rostral deafferentation (Rd) of the MBH was performed (n = 11), and animals in which complete deafferentation (Cd) of the MBH was done (n = 6). Three weeks after the surgical procedures, Cd reduced adenohypophysial weight by 30% and raised its blood flow levels by 80% compared to those values in the Rd and control groups.

Use of immunoperoxidase and immunogold methods in studying prolactin secretion and application of immunogold labelling for pituitary hormones and neuropeptides.

Two immunocytochemical methods, immunoperoxidase and immunogold (IG), were used in an attempt to study the dynamic process of prolactin release from stimulated rat pituitary mammotrophs. The immunogold method was also used to localize other pituitary hormones including growth hormone, follicle-stimulating hormone, luteinizing hormone, and the neuropeptides substance P, neuropeptide tyrosine, leu-enkephalin, and atrial natriuretic factor in peripheral nerves. Light-microscopic immunoperoxidase staining of prolactin revealed a unique distribution of immunoreactive mammotrophs.

Complete suppression of plasma follicle-stimulating hormone in castrated male and female rats during continuous administration of porcine follicular fluid.

The effects of continuous i.v. infusion of porcine follicular fluid (PFF), presumed to contain inhibin activity, on plasma gonadotropin levels were investigated in adult male and female Sprague-Dawley rats.

The differential effects of exposure to tobacco smoke on the secretion of luteinizing hormone and prolactin in the proestrous rat.

The acute effects of tobacco smoke inhalation on the spontaneous proestrous rise in serum luteinizing hormone and prolactin have been investigated in the female Wistar rat. It was found that the surge of LH normally seen throughout the afternoon of proestrus was delayed by inhalation of tobacco smoke and that the delay was dose-related to the nicotine content of the cigarettes used in the experiment. In the case of prolactin neither the timing nor the magnitude of the surge was altered when compared with controls.

Diurnal variation of follicle stimulating hormone (FSH) in the male rat.

The phenomenon of diurnal variation in secretion of FSH, LH and prolactin (Prl) has been investigated in adult male Wistar rats. When these animals were decapitated at 2 h intervals throughout the 24 h day, a highly significant elevation of serum FSH was observed at 12.30 and 14.

Correlation between suckling-induced changes in the ultrastructure of mammotrophs and prolactin release.

Effects of suckling on the structure of mammotrophs and the release of prolactin, were studied in rats on the 10th day of lactation with the use of electron microscopy and radioimmunoassay techniques. Nursing animals were separated from their young for 8 hr and subsequently united and permitted to nurse for 1, 5, 15, 30 min; or 1, 2 and 4 hr. Blood samples were obtained prior to and throughout the suckling interval and pituitary glands were processed for electron microscopy.

Direct effects of estradiol and progesterone on pituitary graft gonadotrophs and their differential response to median eminence extract.

The direct effects of median eminence extract (MEE), estradiol (E) or progesterone (P) or combinations of these hormone preparations on the structure of the adenohypophysis and its secretion of gonadotrophins were examined in female rats bearing pituitary homografts obtained from long-term ovariectomized (LTO) donors. Preliminary investigation had shown that the pars distalis of LTO animals retained large numbers of hypertrophied gonadotrophs for several weeks even when homografted under the kidnay capsule of hypophysectomized recipients. Homografts from vehicle-treated controls contained many gonadotrophs at 24 days.

The interrelation of LH-RH, ovarian steroids and the adenohypophysis.

In this presentation experimental evidence is reviewed and new information is presented concerning the question of cyclic fluctuations in pituitary responsiveness to endogenous and exogenous hypothalamic-releasing hormones as well as the direct role of steroids in modulating pituitary sensitivity. Experiments are described which show that four-day and five-day cyclic rats respond differently to LH-RH, presumably because of differences in secretion patterns of ovarian steroids. The direct role of these steroids in this process was investigated both from the morphological (light and electron microscopy) and physiological (radioimmunoassay measurement of LH) viewpoint in hypophysectomized rats bearing pituitary homografts.

Cholinergic control of the nocturnal prolactin surge in the pseudopregnant rat.

The possible involvement of cholinergic mechanisms in the control of rhythmic secretion of prolactin has been examined in the pseudopregnant rat. Baseline data were obtained in decapitated animals in which the diuranl surge was observed in the 1430--2030 h range and the nocturnal surge during the 2330-0530 h interval. Atrial cannulation permitted a faithful reproduction of the prolactin pattern seen in decapitated rats if at least 3 days elapsed between the cannulation operation and bleeding, while cardiac puncture, under light ether anesthesia, appeared to suppress the diurnal surge.

Ovarian steroids directly alter luteinizing hormone (LH) release by pituitary homografts.

The direct role of estradiol and progesterone in sensitizing the adenohypophysis to the releasing action of LHRH (luteinizing hormone-releasing hormone) has been examined in rats bearing pituitary homografts. Groups (10-14/group) of virgin female rats (CDF) strain) were hypophysectomized, ovariectomized, and pituitaries obtained from long-term ovariectomized donors were implanted under the kidney capsule. The animals were treated on the sixth day after transplantation with sesame oil vehicle, estradiol (1.