Possible Involvement of the Pars Intermedia of the Rat Pituitary in Neurogenic Stress1

2015 ◽  
pp. 193-199 ◽  
Author(s):  
C. Mialhe ◽  
B. Briaud
Keyword(s):  
Pars Intermedia ◽  
Rat Pituitary

THE EFFECT OF INGESTION OF HYPERTONIC SALINE ON THE MELANOCYTE-STIMULATING HORMONE CONTENT AND HISTOLOGY OF THE PARS INTERMEDIA OF THE RAT PITUITARY GLAND

1970 ◽  
Vol 46 (2) ◽  
pp. 201-NP ◽  
Author(s):  
A. HOWE ◽  
A. J. THODY
Keyword(s):  
Control Level ◽  
Pars Intermedia ◽  
Type I ◽  
Melanocyte Stimulating Hormone ◽  
Level Of Activity ◽  
Numerous Type ◽  
Rat Pituitary ◽  
Stimulating Hormone

SUMMARY The changes in the content of melanocyte-stimulating hormone (MSH) and histology of the neuro-intermediate (n.i.) lobe were followed in rats which drank 2% sodium chloride for periods from 1–15 days. The pars intermedia showed a biphasic response. During the initial phase of 1–4 days there was a rapid rise in the MSH content, by 153% in the first day, falling back to control level by 4 days. These fluctuations were paralleled by an increase in the normally small numbers of Type 2 cells and at the same time numerous Type I cells showed hypertrophy and degranulation. After 4 days on saline there was a second rise in the MSH content, which was still evident at 15 days; during this second period the number of Type 2 cells declined to normal levels. The degranulated Type 1 cells also disappeared, most of Type 1 being smaller in size and intensely PAS-positive. After the ingestion of saline it apparently takes several days before the pars intermedia adapts to a new level of activity. The likely significance of these changes and the possibility of a relationship between the pars intermedia and the neurohypophysis are discussed.

ADRENOCORTICOTROPHIC HORMONE IN THE ANTERIOR AND NEUROINTERMEDIATE LOBES OF THE FETAL RAT PITUITARY GLAND

1981 ◽  
Vol 89 (2) ◽  
pp. 181-186 ◽  
Author(s):  
ALAIN CHATELAIN ◽  
J. P. DUPOUY
Keyword(s):  
Pituitary Gland ◽  
Functional Differentiation ◽  
Pars Intermedia ◽  
Adrenocorticotrophic Hormone ◽  
Pars Distalis ◽  
Adult Rats ◽  
Adrenal Cells ◽  
Specific Radioimmunoassay ◽  
Fetal Rat ◽  
Rat Pituitary

The concentration of ACTH in the pars distalis and pars intermedia of the fetal rat hypophysis from days 17–21 of pregnancy was measured with a specific radioimmunoassay and a bioassay using isolated adrenal cells from adult rats. In both lobes of the pituitary gland, a significant correlation was observed between immunoreactive and bioreactive values, expressed as pg equivalents synthetic human 1–39 ACTH per μg protein. In the pars distalis, ACTH concentrations increased steadily from days 17–20 and then remained unchanged to term. At this time they were tenfold higher than on day 17. In the neurointermediate lobe, ACTH was detected only from day 18; the concentration of ACTH increasing between days 18 and 19. At each of the stages of pregnancy examined, the concentration of ACTH in the pars distalis was greater than that in the pars intermedia. These data have demonstrated that ACTH is present in both anterior and neurointermediate lobes of the fetal rat hypophysis, that the functional differentiation of the pars distalis takes place earlier than that of the pars intermedia, and that the concentrations of corticotrophin in the pars distalis and in the pars intermedia have different patterns of development as gestation progresses.

Degeneration and regeneration of nerve terminals in the rat pituitary pars intermedia after 6-hydroxydopamine treatment

1991 ◽  
Vol 2 (5) ◽  
pp. 418-426 ◽  
Author(s):  
L.C. Saland ◽  
J.A. Carr ◽  
A. Samora ◽  
S. Benavidez ◽  
D. Tejeda
Keyword(s):  
Pars Intermedia ◽  
Nerve Terminals ◽  
Rat Pituitary ◽  
6 Hydroxydopamine

Thyrotrophin-releasing hormone stimulates polyphosphoinositide metabolism in the frog neurointermediate lobe

1990 ◽  
Vol 5 (2) ◽  
pp. 129-136 ◽  
Author(s):  
L. Desrues ◽  
M. C. Tonon ◽  
H. Vaudry
Keyword(s):  
Pars Intermedia ◽  
Rapid Loss ◽  
Isotopic Equilibrium ◽  
Thyrotrophin Releasing Hormone ◽  
Phosphatidylinositol Bisphosphate ◽  
Maximal Stimulation ◽  
Rat Pituitary ◽  
Rapid Stimulation ◽  
Stimulation Of ◽  
Polyphosphoinositide Metabolism

ABSTRACT Previous studies have demonstrated that TRH is a potent stimulator of α-MSH secretion from frog pituitary melanotrophs. In order to determine the intracellular events responsible for TRH-evoked α-MSH release, we have investigated the effect of TRH on polyphosphoinositide breakdown in frog pars intermedia. Neurointermediate lobes were labelled to isotopic equilibrium with myo-[3H]inositol. TRH stimulated the rate of incorporation of [3H]inositol into the phospholipid fraction. The effect of TRH was concentration-dependent; half-maximal stimulation of α-MSH release and inositol incorporation occurred at 12 and 28 nmol TRH/1 respectively. In prelabelled neurointermediate lobes, lithium (10 mmol/l) enhanced the radioactivity in inositol monophosphate, bisphosphate (IP2) and trisphosphate (IP3). LiCl (10 mmol/l) induced a 38% inhibition of α-MSH release from perifused neurointermediate lobes but did not impair TRH-induced α-MSH secretion. In the presence of LiCl, TRH (1 μmol/l) induced a transient increase of the radioactivity in IP3, which was evident by 30 s and maximal by 1 min (+ 100%). TRH treatment also increased the radioactivity in IP2, which reached a plateau after 5 min (+ 100%). The increase in radioactivity in IP3 induced by TRH was closely paralleled by a rapid loss of [3H]phosphatidylinositol bisphosphate (PIP2), which was maximal by 1 min (−70%). These results indicate that, in frog pars intermedia, TRH-evoked α-MSH secretion is coupled to breakdown of PIP2. The data suggest that, in amphibian melanotrophs, as previously shown in GH3 tumour cells and in rat pituitary mammotrophs, TRH causes rapid stimulation of polyphosphoinositide-hydrolysing phospholipase C.

scholarly journals Intracellular sites of proteolytic processing of pro-opiomelanocortin in melanotrophs and corticotrophs in rat pituitary.

1991 ◽  
Vol 39 (6) ◽  
pp. 809-821 ◽  
Author(s):  
S Tanaka ◽  
M Nomizu ◽  
K Kurosumi
Keyword(s):  
Polyclonal Antibody ◽  
Secretory Granules ◽  
Protein A ◽  
Proteolytic Processing ◽  
Pars Intermedia ◽  
Gold Particles ◽  
Melanocyte Stimulating Hormone ◽  
Rat Pituitary ◽  
Almost All ◽  
Electron Lucent

A synthetic peptide (ST-1) corresponding to the cleavage site between ACTH and beta-lipotropic hormone moieties of murine pro-opiomelanocortin (POMC) was constructed and its polyclonal antibody was generated. This antiserum immunoprecipitated only POMC from extracts of AtT-20 cells. Moreover, an antiserum raised against porcine ACTH immunoprecipitated both ACTH[1-39] and POMC. When ultra-thin frozen sections of melanotrophs in rat pars intermedia were immunolabeled with anti-ST-1 followed by protein A-gold, gold particles indicating the presence of POMC were selectively found in the electron-dense secretory granules in the Golgi area. In addition, the immunolabeling was also observed in the cisternae of the Golgi apparatus and rough endoplasmic reticulum. In contrast, with a polyclonal antibody specific for alpha-melanocyte-stimulating hormone the gold particles were found exclusively in the electron-lucent secretory granules, with none seen in the electron-dense secretory granules. With anti-ACTH serum, gold particles were observed in the electron-dense and -lucent secretory granules. In corticotrophs in the pars distalis, many gold particles indicating the presence of POMC were observed in the Golgi and peripheral secretory granules, but the percentage of immunolabeling in the peripheral secretory granules varied from cell to cell. On the other hand, ACTH immunolabeling was found in almost all the secretory granules. This finding suggests that the processing of POMC in corticotrophs might occur in the relatively peripheral granules. These results suggest that the intracellular sites of POMC processing are somewhat different between melanotrophs and corticotrophs in the pituitary.

Beta-adrenergic stimulation of the release of ACTH- and LPH-related peptides from the pars intermedia of the rat pituitary gland

1981 ◽  
Vol 97 (3) ◽  
pp. 343-351 ◽  
Author(s):  
F.J. H. Tilders ◽  
M. Post ◽  
S. Jackson ◽  
P.J. Lowry ◽  
P. G. Smelik
Keyword(s):  
Pituitary Gland ◽  
Cortical Cell ◽  
Pars Intermedia ◽  
Intermediate Lobe ◽  
Spontaneous Release ◽  
Adrenergic Stimulation ◽  
Similar Time ◽  
In Vitro Superfusion ◽  
Rat Pituitary

Abstract. The intermediate lobe of the rat pituitary gland produces a series of peptides related to ACTH and LPH. The spontaneous and isoproterenol-stimulated release of such peptides was studied during in vitro superfusion of rat neurointermediate lobes with Krebs-Ringer medium. Products released into the superfusion medium were quantified by direct measurement or after chromatography on Sephadex G-50. ACTH bioactivity was determined by use of adrenal cortical cell suspension assay. In addition, NH2-terminal ACTH, CO2H-terminal ACTH, α-MSH and β-endorphin radioimmunoassays were used. The results show that 1. neurointermediate lobes of rats secrete spontaneously various ACTH- and LPH-related peptides in amounts proportional to the amounts in which these peptides are found in extracts of the neurointermediate lobe; 2. the β-adrenergic agonist, isoproterenol, stimulated the spontaneous release of various peptides, including α-MSH, ACTH, CLIP, glycosylated CLIP, and β-endorphin-like peptides; 3. isoproterenol induced a dose-dependent (10−9–10−7 m), parallel increase in the release of α-MSH and ACTH following similar time courses and showing indentical EC50 values (about 10−8 m). Although the spontaneous release of α-MSH and ACTH from rat neurointermediate lobes is not strictly coupled under the conditions used in this study, isoproterenol seems to affect the spontaneous release of these peptides to the same relative extent.

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