Occurrence of secretogranin II in the prolactin-immunoreactive neurons of the rat lateral hypothalamus: an in situ hybridization and immunocytochemical study.

The occurrence of secretogranin II in a neuron population of the rat lateral hypothalamus specifically detected by an anti-serum to ovine prolactin was examined. As this population was previously reported to synthesize dynorphin, the distribution of neurons recognized by ovine prolactin-, dynorphin B- and secretogranin II anti-sera was investigated on adjacent sections of hypothalami. The prolactin immunoreactive neurons were the only cells in the lateral hypothalamus to be stained by secretogranin II anti-serum. Moreover, coupling immunocytochemical detection and in situ hybridization with an oligonucleotide probe complementary to secretogranin II mRNA showed that these neurons expressed the secretogranin II gene. These new findings should help to study the physiological role of the prolactin immunoreactive neurons of the lateral hypothalamus.

The synthesis of melanin-concentrating hormone is stimulated by ventromedial hypothalamic lesions in the rat lateral hypothalamus: a time-course study.

The activity of melanin-concentrating (MCH) neurons, was investigated by immunocytochemical and hybridocytochemical techniques in male rats bearing limited lesions of the ventromedial hypothalamic nuclei (VMN). 2 days after operation, the abundance of immunoreactive cell bodies and fibres and the intensity of labelling seemed slightly decreased in lesioned rats as compared to controls while no significant difference could be detected in MCH gene expression. After 8 days, synthesis, storage and transport of MCH appeared strongly stimulated and this stimulation lasted until the end of the experiment (day 35), suggesting that VMN plays a physiological role in controlling MCH neuron activity.

Activation of the rat melanin-concentrating hormone neurons by ventromedial hypothalamic lesions.

The occurrence of a melanin-concentrating hormone-like peptide (MCH) was previously reported in the lateral hypothalamus of the rat. The sequence of this peptide was determined but its role as well as its regulation remain unclear. In the present study, we examined the effects of minor electrolytic lesions of the ventromedial nuclei (VMN) on MCH neurons by using immunocytochemical and in situ hybridization procedures. We report that VMN lesions resulted in (1) a clear elevation in the number and staining intensity of MCH immunoreactive perikarya and fibres, (2) a significant increase in the level of hybridocytochemical signal obtained with an oligonucleotide probe complementary to rMCH mRNA. These data provide evidence for a role of VMN in modulating the MCH gene a peptide expression.

Induction of Fos-like immunoreactivity in rat oxytocin neurons following insulin injections.

Double immunostaining for oxytocin (OT) and Fos was used to study the oxytocinergic system of the rat hypothalamic paraventricular nucleus (PVN) following intraperitoneal insulin injections. The expression of c-fos in the PVN appeared about 3 h after insulin treatment and was very high after 5 h while no labelling was observed in isotonic saline-injected animals. Twelve to 18% of OT neurons expressed Fos-like immunoreactivity and these activated neurons were found in both the magno- and the parvocellular compartments of the PVN suggesting that the OT neuron responses to insulin induced disturbances are complex and involve hormonal as well as autonomic pathways.

Evidence for the expression of dynorphin gene in the prolactin-immunoreactive neurons of the rat lateral hypothalamus.

Dynorphin B (DYN B) immunoreactivity was recently reported in a population of prolactin (PRL)-immunoreactive neurons of the rat lateral hypothalamus (LH). By coupling immunocytochemistry and in situ hybridization using two synthetic oligonucleotide probes complementary to DYN mRNA, a hybridization signal was observed over the neurons of the LH exhibiting both DYN- and PRL-like immunoreactivities. Our results clearly demonstrate that these neurons contain the mRNA encoding preproDYN and are able to synthesize authentic DYN B in colocalization with a peptide related to PRL.

Prolactin immunoreactive neurons of the rat lateral hypothalamus: immunocytochemical and ultrastructural studies.

A population of neurons immunoreactive to an antiserum (AS) raised against ovine prolactin (LHPLI neurons) was previously described in the rat perifornical areas and lateral hypothalamus. In the present paper, we demonstrate by complementary immunocytochemical studies using AS to various biologically active peptides or neurotransmitters that these neurons are also detected by AS to bradykinin and to dynorphin B. Electron microscope examination shows that the LHPLI neurons are peptidergic neurons synthesizing apparently only one type of secretory granules. Numerous synapses on their perikarya and processes reflect the complexity of their relationships with other neuron populations, which have yet to be mapped and elucidated.

Colocalization of prolactin- and dynorphin-like substances in a neuronal population of the rat lateral hypothalamus.

Using an antiserum (AS) raised against dynorphin B (DYN B), we revealed immunoreactive neurons in different nuclei of the rat hypothalamus as well as a population of neurons scattered in the lateral areas of the posterior hypothalamus. This population corresponds to that previously shown to be specifically recognized by an ovine prolactin (PRL) AS. Our results suggest that in these neurons, DYN B and PRL AS reacted with different epitopes and that these epitopes could be carried by distinct unidentified peptides.

In vitro metabolism of androstenedione and identification of endogenous steroids in Helix aspersa.

In vitro metabolism of androstenedione in gonads of juvenile and adult Helix aspersa has been investigated. The conversion of [3H]androstenedione into testosterone, 5 alpha-dihydrotestosterone, androsterone, and estriol was demonstrated. In juvenile animals testosterone (59.8%) is the major metabolite whereas in adult animals androsterone (18.8%) is. The following endogenous steroids have been identified by gas chromatography-mass spectrometry in adult gonads: androsterone, dehydroepiandrosterone, androstenedione, 3 alpha-androstanediol, estrone, estradiol-17 beta, and estriol. The levels of testosterone, 5 alpha-dihydrotestosterone, androstenedione, and progesterone have been measured by RIAs in gonads and hemolymph. Their levels vary with the physiological stage: the gonadal and circulating levels of testosterone decrease with the sexual maturation whereas the 5 alpha-dihydrotestosterone increases. These differences observed in metabolism and in level of steroids between the juvenile and the adult snails allow us to suppose that these steroids have a biological role.

[Partial left ovariectomy in the hen: response of the gonadic residue]. / Ovariectomie gauche partielle chez la poule: réponse du reliquat gonadique.

The removal of the left ovary determines a modification of the hormonal environment in the hen, as indicated by the structure of the regenerat frequency observed. Indeed, comparated to the left ovary of the normal females, they present more big follicle and more active steroid cells of the internal theca. This gives evidence of a high stimulation.

[The effect of hybridization on the embryonic germ cell population and the young females produced by the crossing of a male Peking duck with a female Barbary duck (Anas platyrhynchos x Cairina moschata)]. / Effets de l'hybridation sur la population germinale embryonnaire et juvénile de canes issues du croisement Pékin mâles x Barbarie femelles (Anas platyrhynchos x Cairina moschata).

Ovarian development has been studied in a hybrid duck (Anas platyrhynchos male x Cairina moschata female) and in females of the parental Peking and Barbary species. In the hybrid, the gonadal ridge when it first forms is smaller than in either parental species, and after 16 days of incubation there is less cortical growth and less oogonial proliferation. At hatching, the left ovary of the hybrid contains fewer follicles, perhaps because the reduced size of the hybrid gonadal ridge limits germ cell colonization. However, the hybrid follicles develop very rapidly after hatching, and laying begins earlier in the hybrid than in Peking and Barbary ducks.

[Ultrastructure of the granulosa cells of the ovarian follicle of ducks (Barbary duck: Cairina moschata, Pekin duck: Anas platyrhynchos]. / Aspects ultrastructuraux des cellules de la granulosa du follicule ovarien de canes (cane barbarie: Cairina moschata, cane Pékin: Anas platyrhynchos).

In the granulosa cells of the ovarian follicle of the ducks, the Golgi apparatus is developed, the granular endoplasmic reticulum is important. Owing to these characters, these cells are probably oriented towards the elaboration of proteins. The seasonal variations of the aspect of these cells are important: in January all organits are not very developed when in May they are all very developed. For a determined season all cells present the same aspect.

[The steroidogenic sites in the Peking, Barbary and hybrids (Peking male X Barbary female) ducks: histochemistry, ultrastructure, biochemical complements (author's transl)]. / Les sites stéroïdogènes chez les canes Pékin, Barbarie et Hybrides (Pékin male X Barbarie female).

The follicular theca steroid cells are much more numerous in the Peking female than in the Barbary female. Biochemical analyses show that the transfromation percentage of pregnenolone in progesterone is higher in the first than in the second (73% greater than 52%); in the same way, we dose more plasmatic oestradiol in the Piking than in the Barbary female (160 pg/ml greater than 69 pg/ml). In the hybrid female, resulting from the crossing of Peking male X Barbary female, many steroid cells are destroyed during the aging process; the transformation percentage in then 14,50% (30% in the young females) and the seric concentration is 7 pg/ml (59 pg/ml in the young females).

[The germinal population at embryonic stage and young age in the female hybrid duck born of male Pekin x female Barbary crossing. Comparison with ducks of the parent species]. / La population germinale aux stades embryonnaires et juvéniles chez la cane hybride issue cu croisement pékin male x barbarie female. Comparaison avec les carnes des espèces parentes.

As hatching the number of left ovary germinal cells of the female hybrid (Anas platyrhynchos x Cairina moschata) is weaker than that of the Peking and Barbary females because the small size of the genital crest limites the number of colonising germinal cells. As well after 16 days of incubation the multiplication of the oogonies stops in a way that we can not explain. The later growth of the ovarian follicle is, however, very fast, and the first laying is earlier than with the female parents.

[Ultrastructural aspects of cells with 3 beta-HSDH (delta-5-betahydroxysteroid dehydrogenase) activity in female ducks. I. Female Peking duck (Anas platyrhynchos)]. / Aspects ultrastructuraux des cellules à activité 3 beta-HSDH (delta5-3 beta-hydroxystéroïde déshydrogénase) chez les canes. I. Cane Pékin (Anas platyrhynchos)

The cells making up the thick internal theca of the follicle of the Peking duck and which contain an active 3 beta HSDH enzyme have a developed smooth reticulum, tubular crested mitochondria, a considerable load in slightly osmiophilic lipid inclusions; all of these characteristics are those of steroid cells. Various physiological states of these cells juxtapose themselves in different proportions according to the season.

[Ultrastructural aspects of cells with 3 beta-HSDH (delta 5-3 betahydroxysteroid dehydrogenase) activity in female ducks. II. Female Barbary ducks (Cairina moschata)]. / Aspects ultrastructuraux des cellules à activité 3 beta-HSDH (delta 5-3 beta-hydroxystéroïde déshydrogénase) chex les canes. II. Cane Barbarie (Cairina moschata)

The cells making up the thin internal theca of the follicle of the Barbary duck and which contain are 3 beta HSDH enzyme show all of the ultrastructural characteristics of steroid cells: a well-developed smooth reticulum, tubular cristae mitochondria, a considerable load in lipid inclusionologous cells of the Peking duck since they are constantly more dense and their cristae are bigger and less numerous.

[Ultrastructure of 3 beta HSDH (delta 5-3 beta hydroxysteroid dehydrogenase)-containing cells in ducks. III. Hybrid ducks (Anas platyrhynchos male X Cairina moschata female) during egg laying]. / Aspects ultrastructuraux des cellules à activité 3 beta HSDH (delta 5-3 beta hydroxystéroïde-déshydrogénase) chez les canes. III. Cane hybride (Anas platyrhynchos male X Cairina moschata female) en période de ponte

All the cells of the ovary of the hybrid duck (Peking duck X Barbary duck) which contain an active 3 beta HSDH enzyme show ultrastructural characteristics of steroid cells: a smooth, developed reticulum, tubularcrested mitochondria, a considerable "charge" in lipid inclusion. These cells are found not only in the internal theca of follicles as with the female gender, but also in the cortical zones void of germinal elements, a tendancy particular to the female.