Immunocytochemistry of gonadotropic cells in the pituitary of Pomadasys jubelini (teleost fish).

An antibody specific for the beta subunit of carp gonadotropin was applied to pituitary sections from Pomadasys jubelini in order to characterize and localize the gonadotropic cells by immunocytological means. It reveals the gonadotropic zone lying mainly at the periphery of the proximal pars distalis with lateral extensions around the pars intermedia. The separation between the pars proximalis and the pars intermedia is irregular. Short finger-like extensions of the gonadotropic zone protrude more or less into the pars intermedia. The immunocytological results corroborate previous tentative identifications of the gonadotropic cells by classical cytological methods and suggest that the gonadotropic hormone produced is immunologically related with several previously studied fish gonadotropins.

Circulating forms of alpha MSH in the carp and trout blood: an HPLC and RIA study.

The three forms of MSH(desacetyl-, monoacetyl-, and diacetyl) circulate in the carp and trout blood. Their proportions there are as follows: in the carp, the desacetylated form is 2.5% of total MSH and the monoacetylated form 72% of the acetylated forms of alpha MSH. In the trout, similar proportions were found: desacetyl alpha MSH was 5% of total alpha MSH and monoacetyl-, 70% of the acetylated MSHs.

Proportions of mono- and diacetylated forms of alpha MSH in individual neurointermediate lobe extracts of Cyprinus carpio L.

The proportions of the mono- and diacetylated forms of alpha MSH in individual carp neurointermediate lobe (NIL) extracts, as assessed by HPLC and RIA, fluctuate within a narrow range (mono/mono- + diacetyl alpha MSH = 3-14%). These results obtained on individuals of different sex and age show that the diacetylated form predominates in the NIL of all individuals where it represents in the mean 90% of the acetylated forms. The relatively low fluctuation of the proportions of the acetylated forms suggests that the possibility for a physiological modulation of the diacetylation step may be limited in this species of fish.

Separation and partial characterization by high-performance liquid chromatography and radioimmunoassay of different forms of melanocyte-stimulating hormone from fish (Cyprinidae) neurointermediate lobes.

From neurointermediate lobe (NIL) extracts of two species of Cyprinidae, Carassius auratus and Cyprinus carpio, several peptides were separated by high-performance liquid chromatography (HPLC) on a C18 muBondapak column eluted with a methanol/acetic acid/triethylamine mixture. Monitoring all fractions by radioimmunoassay (RIA) with an antibody against melanocyte-stimulating hormone (MSH) C terminal gave positive reactions for fractions 7, 11-12, 15-16, 23-24, and 25-27. For further characterization, the elution positions of these peaks were compared to those of known synthetic reference substances. Peak 7 elutes in the same position as oxidized alpha MSH, whereas peak 15-16 matches the elution position of des-acetyl alpha MSH and 23-24 that of alpha MSH. The product from peak 26-27 has several characteristics of the diacetylated form of alpha MSH: its immunoreactivity in RIA, its sensitivity to weak bases and to HCl and its mass spectrum which is identical with that of mammalian diacetyl alpha MSH. In both species, the diacetylated form is predominant in the intracellular pool. This study establishes the coexistence of three different forms of alpha MSH, a des-acetylated, monoacetylated, and diacetylated in the cyprinid NIL extracts.

Relationships between the tubular system in the globules of the coronet cells of the saccus vasculosus and the cerebrospinal fluid in Gasterosteus aculeatus form leiurus (Teleostei).

In the stickleback, Gasterosteus aculeatus, the globules of the coronet cells in the saccus vasculosus contain a tubular system that most probably communicates permanently with the lumen of the saccus. Only very few openings were found in random ultrathin sections. Injecting peroxidase into the cerebrospinal fluid revealed the communication between this tubular system and the cerebrospinal fluid. As early a 1 h after peroxidase injection the tracer was detected in the tubular system. This system increases the potential exchange surface between the coronet cells and the content of the saccular lumen, and may also facilitate the access of components of the cerebrospinal fluid (CSF), even of high molecular weight, into the globules. It remains to be determined whether the intratubular condensations (granules) are, as often believed, of secretory origin or are formed by accumulation of components of the CSF.

[Melanotropic hormone of goldfish (Carassius auratus L.): radioimmunologic comparison with synthetic alpha-MSH]. / L'hormone mélanotrope du Poisson rouge (Carassius auratus L.): comparaison radio-immunologique avec l'alpha MSH de synthèse.

alpha MSH from the neuro-intermediate lobe of the pituitary gland of the goldfish displays a competitive behaviour in an RIA for synthetic alpha MSH. The inhibition curves from neuro-intermediate homogenates parallel the standard curve (P < 0,01) but two major pools of immunoreactive peptides have been separated by Sephadex gel chromatography. The neuro-intermediate lobe contains 480 +/- 56 ng (S.E.M.) of immunoreactive alpha MSH.

[Localization of immunoreactive sites with anti met-enkephalin and anti alpha-endorphin sera in carp brain]. / Localisation des sites immunoréactifs avec un antisérum contre la met-enképhaline et contre l'alpha-endorphine dans le cerveau de la carpe.

In the brain of the Carp an anti met-enkephalin serum reveals some telencephalic fibres, about half of the N.P.O. cells and furthermore a subependymal zone of nervous tissue close to the third ventricle of the superior hypothalamus and thalamus. These structures do not react with an anti alpha-endorphin serum, which however reveals cells of the lateral N.L.T. and the corresponding fibres.

[Immunocytologic differentiation of hypophyseal innervation in carp using anti met-enkephalin and anti-alpha-endorphin serums]. / Différenciation immunocytologique de l'innervation hypophysaire de la Carpe à l'aide de sérums anti met-enképhaline et anti-alpha-endorphine.

The immunocytological reactions with anti-met-enkephalin and anti-alpha-endorphin reveal two types of fibres in the intermediate lobe of the Carp. Their pathways through the adenohypophysis and the localization of their terminals are different. The anti-met-enkephalin positive fibres terminate mainly in a zone close to the proximal pars distalis; however some fibres terminate deeper in the intermediate lobe. The anti-alpha-endorphin positive fibres penetrate mainly in the central and ventral part where thye are more numerous than the former. It seems that the anti-met-enkephalin positive fibres belong to the gomori positive preoptico-hypophyseal tract, whereas the anti-alpha-endorphin positive fibres are gomori negative.

[Immunocytology of alpha-endorphin positive hypothalamic fibers of Carassius auratus L. and Cyprinus carpio L]. / Etude immunocytologique des fibres alpha-endorphine positives de l'hypothalamus de Carassius auratus L. et Cyprinus carpio L..

An immunocytological study of the basal hypothalamus of Carassius auratus and Cyprinus carpio with an alpha-endorphin antiserum shows the different nerve processes belonging probably to the immunoreactive cells of the lateral part of the N.L.T. According to their pathways, two main fibre tracts have been distinguished: many fluorescent fibres converge towards the pituitary gland into which they enter, other fibres run caudally through the tuber towards the nucleus tuberis inferior (Baumgarten and Braak) where they could not be followed further.

Distribution of fibres reacting with an alpha-endorphin antiserum in the neurohypophysis of Carassius auratus and Cyprinus carpio.

A strong positive immunoreaction with an alpha-endorphin antiserum occurs in two distinct sites of the goldfish and carp neurohypophysis. Fluorescent nerve terminals are found in the laminar nerve processes located in the rostral pars distalis, but the immunocytological reaction is mainly localised on the nerve processes of the posterior neurohypophysis lying between the intermediate lobe cells. Almost all the digitations of the neurohypophysis are strongly fluorescent. The immunoreactive fibres probably originate from the hypothalamus, where perikarya displaying the same immunoreaction have been found in the pars lateralis of the nucleus lateralis tuberis and in some minor centres. The possibility that the immunoreactive substances revealed on the neurohypophyseal processes may originate in the intermediate lobe cells is also discussed. It has now to be established if this hypothalamo-hypophyseal system contains a substance with endorphic properties or only some immunologically related substance devoid of the corresponding physiological activities.

Immunocytological detection and localization of a peptide reacting with an alpha-endorphin antiserum in the corticotropic and melanotropic cells of the trout pituitary (Salmo irideus Gibb).

In the pituitary of the trout, the corticotropic and melanotropic cells display a strong immunocytological reaction with alpha-endorphin antiserum. This reaction persists even when alpha-endorphin antisera treated with beta-1-24ACTH or alpha-MSH are used. In the absence of pharmacological tests on the endorphic potencies of the compounds involved in the immunoreaction, it is not yeat clear whether this reaction is due to the presence of an alpha-endorphin-like peptide or simply an immunologically related peptide without the properties of endorphin. However, the presence of such peptides in the fish pituitary is interesting from the comparative point of view.

[Immunocytological localization of peptide analogs of alpha-endorphin in several neurons of the lateral nucleus tuberis of Carassius auratus L. and Cyprinus carpio L]. / Localisation immunocytologique de peptides analogues à l'alpha-endorphine dans certains neurones du noyau latéral du tuber de Carassius.

Neurons of the pars lateralis of the N.L.T. of Carassius auratus and Cyprinus carpio display a positive immunocytological reaction with an anti alpha-endorphin serum. It is assumed that the peptides produced by these neurons are similar, if not identical, with alpha-endorphin, but their morphinomimetic properties have still to be established. Peptides of this kind may participate in the regulation of pituitary functions.

[Inhibition of corticotropic function by administration of GABA in carp (Cyprinus carpio L.)]. / Inhibition de la fonction corticotrope par l'administration de GABA chez la carpe (Cyprinus carpio L.).

The intracardiac injection (50 microgram/g) of GABA to Carps clearly inhibits the rise of the plasma cortisol level which occurs usually in response to the blood sampling manipulations. The inhibition starts thirty minutes after injection and lasts till the end of the experiment two hours later. The hypothesis that this neurotransmitter has a regulatory function on the corticotrop cells, especially on the excretion of ACTH has to be considered.