Ultrastructural, immunocytochemical and morphometric studies of pituitary prolactin cells after chronic administration of met-enkephalin.

The effects of chronic administration of met-enkephalin (40 micrograms/day, for 20 days) on the pituitary prolactin cells of Wistar male rats were studied at the light (PAP-immunohistochemical for PRL demonstration technique) and electron microscopy levels. The D. CIRCLE (mean diameter), D. MAX (maximum diameter) and FORM PE (circular factor of form; irregularity degree) form secretory granules, as well as their percent distribution, were also evaluated. The cellular alterations were variable. Most prolactin cells showed an increase in immunohistochemical reaction. At the electron microscope level the prolactin cells showed an enlargement and swelling of the RER and Golgi apparatus. The secretory granules were bigger and more spherical in experimental than in untreated and control animals. A number of cells showed a variable number of cytoplasmic vacuoles or a large central vacuole formed from dilated RER-cisternae. The authors discuss the possible mechanism whereby met-enkephalin exerts a control on prolactin cells.

Study of the rat TSH-producing cells after met-enkephalin treatment: effects of dopamine antagonists.

The effects of single and repeated doses of met-enkephalin (Met-E) on the ultrastructure and TSH-like immunoreactivity (IR) of pituitary TSH-producing cells, and TSH plasma levels in male rats and the influence of pretreatment with a dopamine antagonist, haloperidol, on these, were evaluated. Both acute and repeated Met-E administration produced changes in TSH cells consisting of: an increase in TSH-like IR, enlargement and dilation of RER and Golgi apparatus, size-increase of secretory granules, and the presence of a variable number of cytoplasmic vacuoles. The ultrastructural changes were more evident in the chronically treated animals, whereas no differences were found in IR-intensity between both Met-E treated groups. Haloperidol alone modifies neither ultrastructure nor TSH-like IR of TSH producing cells, but it prevented the Met-E produced changes. On the other hand, Met-E treatment resulted in a decrease of TSH plasma levels, but being significant only in the acutely injected animals. No variations were produced by haloperidol alone, but it prevented the decrease of TSH plasma levels stimulated by Met-E. Our results suggest that Met-E plays a role in the release of TSH, and that dopamine is implicated in this process. The possible mechanisms through which Met-E influences TSH secretion are discussed.

Effects of morphine on the pituitary-thyroid axis: morphological and analytical studies.

The morphology of the TSH-producing pituitary cells and the thyroid gland, and plasma TSH, T3 and T4 hormone levels, were studied in normal rats, in rats treated with 10 micrograms morphine (M) and in M-treated animals pretreated with naloxone (Nx) (10 mg/kg). Morphological changes in the pituitary TSH cells and thyroid cells of M-treated animals were minimal and were not modified by Nx pretreatment. Plasma TSH levels in M-treated animals showed a significant decrease (P less than 0.05), which was not blocked by Nx pretreatment. No significant changes in plasma T3 or T4 levels were found in either experimental group.

Immunohistochemical localization of S-100 protein subunits (alpha and beta) in dorsal root ganglia of the rat.

The distribution of S-100 protein and their subunits (alpha and beta) in lumbar dorsal root ganglia of adult rat was investigated immunohistochemically using monoclonal antibodies against the S-100 protein, alpha-subunit and beta-subunit of S-100 protein. The conventional S-100 protein antibody stained both neurons (large and intermediate in size; 20.3% and 41 +/- 3.2 microns of diameter) and glial cells (satellite cells and Schwann cells). The immunoreaction for the alpha-subunit was observed in the perikarya of some large and intermediate sized neurons (17.2%, 45.6 +/- 6.1 microns of diameter), satellite cells and Schwann cells, whereas the beta-subunit immunoreactivity was found principally in glial cells, and in a scarce number of large and intermediate sized neurons (2.8%, 43.3 +/- 5 microns of diameter) Our results demonstrate that a subpopulation of large and intermediate sized neurons of lumbar DRG contain alpha- and beta-subunits of S-100 protein, being alpha-subunit predominant. Furthermore, the satellite glial and Schwann cells contain also the two subunits but mainly beta-subunit. These data confirm previous studies about the presence of S-100 protein in neurons of the central and peripheral nervous system.

[Osseointegration of IMZ implants. Ultrastructural analysis of a case]. / Oseointegración de los implantes IMZ. Análisis ultraestructural de un caso.

A study with scanning electron microscope of an osseointegrated titanium implants (IMZ) was performed, analyzing the characteristics of the interface bone--titanium oxid. It was observed that the characteristics of the interface were similar to the ones shown by other devices whose design is different (Branemark system). The present study confirms that an adequate surgical technique and a satisfactory post-operation on phase (in which the implant is free of load) lead to the osseointegration of the implant; this facts is proved by the absence of mobility of the device, and also by structural findings typical of normal osseous tissue.

Effects of met-enkephalin on the adrenocorticotropic cells of the rat pituitary.

The effects of chronic administration of met-enkephalin (40 micrograms/d during 20 days) on ACTH producing cells of the rat adenohypophysis have been studied both in light (PAP-immunocytochemistry for ACTH) and electron microscope. In addition a morphometric analysis and a percent distribution of secretory granules were performed. The ACTH cells of treated animals showed ultrastructural signs of hyperactivity, and some of them vacuolization (small vacuoles or a large central vacuole). The secretory granules of the experimental animals are larger and more spherical than the ones in the untreated and the control animals. We discuss the possible mechanism of action whereby met-enkephalin influences ACTH cells.

Immunohistochemical study of Pacinian corpuscles using monoclonal antibodies for neurofilament protein, glial fibrillary acidic protein and S-100 protein.

The presence of neurofilament protein (NFP), glial fibrillary acidic protein (GFAP) and S-100 protein has been investigated in Pacinian corpuscles from cat's mesentery by means of immunohistochemical methods. The NFP-like positivity was found in the central axon of the corpuscles; the GFAP- and S-100 protein-like immunoreactivities were shown in the innermost layers of the differentiated cell of the inner core. No positive reaction was detected in the capsule. The authors discuss these findings.

Semi-automatic morphometric analysis of secretory granules in the cells of the rat adenohypophysis.

The authors carried out a morphometric analysis--using a semi-automatic system for image analysis--of the secretory granules in the cells of the Wistar rat adenohypophysis. They evaluated the mean diameter (CIRCLE D), maximum diameter (MAX D), the factor of circular form (PE FORM) and the harmonic factor of form (HAR FORM). They also computed the coefficient of correlation between CIRCLE D and PE FORM and the percentual distribution of the values according to mean diameter.

Expression of cytoskeletal proteins in glial cells of dorsal root ganglia.

The localization of S-100 protein-, glial fibrillary acidic protein- and vimentin-like immunoreactivity has been studied in dorsal root ganglia of the rat using monoclonal antibodies. A positive reaction for both S-100 protein-like and vimentin-like was found in satellite and Schwann cells. In addition, some large and intermediate sized neurons also result S-100 protein-like immunoreactivity. No positive reaction for glial fibrillary acidic protein-like was observed. The authors discuss these results.

Study of the gonadotropic cells in the rat after chronic administration of met-enkephalin: light, electron microscope and image analysis.

The effects of a chronic administration of met-enkephalin (40 micrograms/day, for 20 days) on the pituitary gonadotropic cells of Wistar male rats were studied in light (PAS alcian blue-orange G and PAP-immunohistochemical for FSH and LH demonstration techniques) and by electron microscope. Also the D CIRCLE (mean diameter) and FORM PE (circular factor of form; irregularity degree) from secretory granules of these cell types were evaluated. The cellular alterations are variable. Gonadotropic cells show an increase on the cytoplasmic basophilia and immunohistochemical reaction. At the electron microscope level the gonadotropic cells show an enlargement and dilatation of RER and Golgi apparatus. The secretory granules are bigger and more spherical in experimental than in normal and control animals. A lot of cells show a large cytoplasmic vacuole which is formed from dilated RER-cisternae. The authors discuss the possible mechanism of action whereby met-enkephalin exerts control on gonadotropic cells.