Changes of melanin-concentrating hormone related to LHRH release in the median eminence of rats.

The present research was carried out to study the distribution of melanin-concentrating hormone (MCH) fibers in the median eminence of rats and to evaluate if changes in the MCH content of the median eminence could be related to the release of LHRH. Immunocytochemical studies in the median eminence of males and estrous females showed the presence of MCH fibers, mainly in its internal layer. Diestrous and proestrous animals displayed MCH immunoreactivity in both the internal and external layers of the median eminence.

Peptidergic innervation of blood vessels and interstitial cells in the testis of the cat.

We studied the innervation of the cat testis using a panel of antisera against the following neuronal markers: protein gene product 9.5 (PGP), neuropeptide Y, C-terminal peptide of neuropeptide Y, galanin, vasoactive intestinal peptide (VIP), calcitonin gene-related peptide, and substance P. Immunoreactivity against PGP, a general neuronal label, demonstrated the arrangement of fibers from the superior spermatic nerve (SSN) in the testicular pedicle and the cephalic testicular pole, and those of the inferior spermatic nerve (ISN) along the vas deferens and the inferior testicular ligament.

Coexistence of neuropeptides and their possible relation to neuritic regeneration in primary cultures of magnocellular neurons isolated from adult rat supraoptic nuclei.

The coexistence of vasopressin (VP), oxytocin (OXY), galanin (GAL) and cholecystokinin (CCK) and the synthesis of GAL and CCK during neuritic regeneration was investigated in cultured magnocellular neurons, isolated from adult rat supraoptic nuclei. Double-labelling immunofluorescence was performed after 7 days of culture using primary antibodies for VP, OXY, GAL and CCK (paired in all possible combinations) and secondary antibodies labelled with either fluorescein or rhodamine. Confocal laser scanning microscopy revealed the coexistence of the mentioned peptides in all possible combinations, an unexpected result considering that the only combinations observed in tissue sections are VP-GAL and OXY-CCK.

Melanin-concentrating hormone stimulates the release of luteinizing hormone-releasing hormone and gonadotropins in the female rat acting at both median eminence and pituitary levels.

The purpose of this study was to investigate whether melanin-concentrating hormone (MCH) acts directly on the median eminence and on the anterior pituitary of female rats regulating LHRH and gonadotropin release. In addition, immunohistochemistry was used to examine the density and distribution of MCH-immunoreactive fibers in the median eminence of proestrous rats. MCH-immunoreactive fibers were found in both the internal and external layers of the median eminence and in close association with hypophysial portal vessels.

Hormone uptake and morphological changes in cultured pituicytes exposed to oxytocin and vasopressin.

Enzymatically dispersed cells, isolated from adult female rat neural lobes, were cultured for 7 days. Routine cultures showed pituicytes with compact, sometimes ovoid, cell bodies. The cytoplasmic processes of these cells exhibited several varicosities and made contact with neighboring cells forming networks.

Neuropeptide tyrosine-like immunoreactivity (NPY-LI) in ganglion neurons in the adrenal gland of the flat snake (Waglerophis merremii).

In previous morphological and histochemical studies on the adrenal gland of the flat snake, no data demonstrating the existence of ganglion neurons has been reported. The aim of this paper was therefore to establish the presence of ganglion neurons in the adrenal gland of the flat snake Waglerophis merremii and, further to study their chemical phenotype using immunohistochemistry. Our results showed the presence of cells which were immunolabelled with the neuronal marker neurofilament 10 and were thus identified as large ganglion neurons.

Differential effects of superior and inferior spermatic nerves on testosterone secretion and spermatic blood flow in cats.

It has been postulated that testosterone secretion is partially regulated by signals from the spermatic nerves. To further examine this hypothesis in vivo, the superior (SSN) or the inferior (ISN) spermatic nerves were stimulated electrically (varying intensity, 25 Hz, 0.2 msec, 10 min) in anesthetized cats, determining the testosterone concentration and the blood flow in the spermatic vein.

Suckling-induced serum prolactin levels are modified by interference with milk ejection in lactating rats.

The aim of this study was to determine whether suckling-induced prolactin (PRL) levels were modified when milk ejection was impaired. Milk ejection impairment was achieved in two experimental models: a) depriving the dam of sleep during suckling and b) increasing the nonsuckling intervals in lactating dams. Sleep deprivation blocked milk ejection and enhanced suckling-induced PRL levels in dams that had been previously separated from their pups.

Galanin and cholecystokinin in cultured magnocellular neurons isolated from adult rat supraoptic nuclei: a correlative light and scanning electron microscopical study.

Cultured magnocellular neurons, isolated from adult rat supraoptic nuclei, were characterized by immunocytochemistry, using the avidin-biotin-peroxidase complex and antisera to vasopressin, oxytocin, galanin and cholecystokinin. Light microscope examination of the immunostained cultures revealed the presence of vasopressin- and oxytocin-like immunoreactivity, as well as neurons containing either galanin- or cholecystokinin-like immunoreactivity. In contrast, no significant galanin- or cholecystokinin-like immunoreactivity could be observed in freshly dispersed cells.

Involvement of Catecholestrogens in the release of pituitary hormones.

Catecholestrogens (CE), natural metabolic products of 17ß-estradiol and estrone, were assayed in anterior and posterior pituitary lobes and in the median eminence of the rat. The highest CE values were found in the median eminence and the lowest in the anterior pituitary. The CE concentrations in pars nervosa and pars intermedia of the posterior pituitary were quite similar.

Growth hormone inhibits the hypophysectomy-induced expression of galanin in hypothalamic neurons of the toad (Bufo arenarum hensel).

The expression of the neuropeptide galanin was analyzed by immunohistochemistry in magnocellular and preoptic hypothalamic neurons of toads following hypophysectomy (HPX) and pars distalectomy (PDX). There was a marked increase in the galanin-like immunoreactive expression in magnocellular hypothalamic cells 3 days after HPX, followed by a decrease to normal levels after 7 days. No changes in the expression of galanin were detected after PDX in these neurons when compared to controls.

Dispersion and culture of magnocellular neurons from the supraoptic nucleus of the adult rat.

A simple and efficient procedure for the dispersion and culture of magnocellular neurons of the adult rat hypothalamus was developed. The enzymatically and mechanically dispersed cells were highly viable and showed neurite outgrowth after 3 days of culture. The neurons could be maintained for more than 4 weeks without any sign of deterioration.

NPY- and CGRP-like immunoreactive nerve fibers in the testis and mesorchium of the toad (Bufo arenarum).

The presence and distribution of peptidergic nerve fibers were studied in the testis and mesorchium of the toad by means of immunohistochemistry. Cryostat sections of the testis and whole-mount preparations of mesorchia were immunostained with antisera to calcitonin gene-related peptide (CGRP) and neuropeptide tyrosine (NPY). After leaving the mesorchium CGRP-immunoreactive (IR) fibers were seen predominantly running in between the seminiferous tubules.

Galanin-like immunoreactive expression in the central nervous system of the toad.

The distribution of galanin (GAL)-like immunoreactivity (-LI) was studied in the CNS of the toad (Bufo arenarum Hensel). Tissue sections were incubated with antibodies directed toward rat or porcine GAL and processed either for the avidin-biotin complex, or for the indirect immunofluorescence techniques. In the telencephalon GAL-immunoreactive (-IR) perikarya were observed in the ventral part of the striatum and in the septal accumbens nuclei.

Monoaminergic and peptidergic contributions of the superior and the inferior spermatic nerves to the innervation of the testis in the rat.

Sections of the rat testis and whole-mounts of the testicular capsule were studied microscopically using the glyoxylic acid-induced fluorescence method, to detect monoamines, and immunohistochemical procedures for the detection of immunoreactivities to protein gene-product 9.5 (PGP 9.5), the C-terminal accompanying peptide of neuropeptide Y (CPON), and vasoactive intestinal polypeptide (VIP).

Immunohistochemical localization of neurotensin in a subpopulation of noradrenergic chromaffin cells of the adrenal gland of the flat snake (Waglerophis merremii).

The distribution of neurotensin (NT)-like immunoreactivity (LI) in the adrenal gland of the snake Waglerophis merremii has been examined immunohistochemically. Double staining, combining NT with tyrosine hydroxylase (TH) or calcitonin gene-related peptide (CGRP) antibodies and TH with CGRP antibodies, was also carried out. Results were analyzed by conventional and by confocal fluorescence microscopy.

NOS is present in the brain of Triatoma infestans and is colocalized with CCK.

Immunohistochemistry was used to establish the presence of nitric oxide synthase (NOS) in the central nervous system of Triatoma infestans which is the main vector for Chagas' disease in Argentina and neighbouring countries. In addition, we have investigated the presence of cholecystokinin (CCK) and studied the possible coexistence of these molecules. The results show NOS-like immunoreactivity (LI) in neurones of the soma rind of the protocerebrum, the optic lobe and in the lateral part of the sensory deutocerebrum with a few cells in the suboesophageal and the prothoracic ganglia.

Histochemical study of chromaffin cells and nerve fibers in the adrenal gland of the flat snake (Waglerophis merremii).

The distributions of tyrosine hydroxylase (TH), protein gene product (PGP) 9.5, calcitonin gene-related peptide (CGRP), and peptide histidine isoleucine (PHI) have been examined immunohistochemically in the adrenal gland of the snake Waglerophis merremii. The morphology of chromaffin cells and the presence of ganglionic neurons in the gland revealed by means of the glutaraldehyde-silver technique and electron microscopy are also described.

Suckling-induced changes of vasoactive intestinal peptide concentrations in hypothalamic areas implicated in the control of prolactin release.

The present study was designed to investigate whether the vasoactive intestinal peptide (VIP) concentration in hypothalamic nuclei, dorsal raphe nucleus (DR) and pituitary lobes of lactating rats changes in physiological situations when prolactin (PRL) secretion is stimulated (suckling) or inhibited (pup separation). In addition VIP levels in blood plasma were determined in both situations. Acute suckling induced changes in VIP concentration only in the rostral part of the anterior hypothalamic (rAHN) and the paraventricular (PVN) nuclei of all the brain areas examined.

Release of prolactin and growth-hormone by pituitary grafts. Role of the neurointermediate lobe.

The release of prolactin (PRL) and growth hormone (GH) of pituitary grafts and in situ glands was investigated using perifusion techniques. Whole pituitary or anterior lobe grafts were used. The grafts or the in situ glands were incubated alone in a chamber.

[Regulation of prolactin secretion at the cellular level].

The present review compiles and discusses about two decades of research concerning the mechanisms involved in the regulation of the secretory activity of mammalian prolactin (PRL) containing cells. The topics include methodological aspects (such as dispersion, culture and isolation of anterior pituitary cells), the action of catecholamines, second messengers (calcium, cyclic AMP and phosphatidylinositol metabolites), neuroendocrine modulators and peptides, as well as a chapter about the morphology and biochemistry of the PRL secretory granule. Most of the accumulated data--often dispersed or disconnected--do not allow definitive conclusions and it becomes clear that we are still far away from understanding the mechanisms regulating PRL secretion.

Electronmicroscopic and electrophysiological studies of the teat branch of the XIII thoracic nerve: relationship with lactation in the rat.

Electrical stimulation of the XIII thoracic nerve (the 'mammary nerve') causes milk ejection and the release of prolactin and other hormones. We have analysed the route of the suckling stimulus at the level of different subgroups of fibres of the teat branch of the XIII thoracic nerve (TBTN), which innervates the nipple and surrounding skin, and assessed the micromorphology of the TBTN in relation to lactation. There were 844 +/- 63 and 868 +/- 141 (S.

Dorsal raphe lesion alters the estrous cycle and the preovulatory gonadotropin release.

The purpose of this study was to examine the role that the dorsal raphe (DR)-median eminence (ME) serotonergic projection may have in the proestrous gonadotropin and prolactin (PRL) release. DR electrolytic lesions were performed in cycling rats during the first day of diestrus. The effect of DR lesions after 48-72 h of survival (short-term lesioned animals) or after 35-40 days of survival (long-term lesioned animals) on estrous cyclicity, preovulatory gonadotropin and PRL releasing pattern, ovulation and serotonin (5-HT) content of the ME were studied.

Serotonergic terminals in the anterior hypothalamic nucleus involved in the prolactin release during suckling.

The present studies were designed to localize within the hypothalamus and neighboring areas the serotonergic terminals which are implicated in suckling-induced PRL release. The initial experiments were performed to characterize the circulating hormone profile induced by suckling in lactating rats, previously separated from their pups. Five minutes of suckling induced an increase in serum PRL only.