Jun localization in cytosolic and nuclear compartments in brain-pituitary system of the frog, Rana esculenta: an analysis carried out in parallel with GnRH molecular forms during the annual reproductive cycle.

The presence of c-jun like mRNA was assessed in the brain of the frog, Rana esculenta, during the annual sexual cycle. In parallel, Jun protein and GnRH molecular form (mammalian and chicken II also indicated as GnRH1 and GnRH2, respectively) activity was studied in order to establish possible relationships. Northern blot analysis of total RNA reveals the presence of a 2.7 kb c-jun-like mRNA. Western blots, carried out on cytoplasmic and nuclear protein extracts, show the presence of Jun immunoreactive band of 39 kDa in brain and pituitary. Fluctuations of c-jun-like mRNA and Jun immunoreactive protein (cytoplasmic and nuclear) levels in brains during the year indicate relationships among transcription, translation, and nuclear activity. In particular, mRNA levels increase gradually from September until November when Jun protein concentration peaks in cytosolic extracts. Conversely, the nuclear protein reaches highest concentration in July when the cytosolic level shows low values. Immunocytochemical studies confirm the presence of Jun immunoreactivity in both cytoplasmic and nuclear compartments of several brain areas, including those primarily involved in gonadotropin discharge (e.g., anterior preoptic area and preoptic nucleus). GnRH molecular forms and Jun are colocalized in anterior preoptic area and preoptic nucleus. Moreover, during the period characterized by GnRH release, Jun levels strongly decrease in nuclei. Finally, we show that treatments with a GnRH analog (buserelin, Hoechst, Frankfurt) increase Jun levels in brain nuclear extracts.

Pituitary adenylate cyclase-activating polypeptide and its receptors in amphibians.

Pituitary adenylate cyclase-activating polypeptide (PACAP), a novel peptide of the secretin/glucagon/vasoactive intestinal polypeptide superfamily, has been initially characterized in mammals in 1989 and, only 2 years later, its counterpart has been isolated in amphibians. A number of studies conducted in the frog Rana ridibunda have demonstrated that PACAP is widely distributed in the central nervous system (particularly in the hypothalamus and the median eminence) and in peripheral organs including the adrenal gland. The cDNAs encoding the PACAP precursor and 3 types of PACAP receptors have been cloned in amphibians and their distribution has been determined by in situ hybridization histochemistry. Ontogenetic studies have revealed that PACAP is expressed early in the brain of tadpoles, soon after hatching. In the frog Rana ridibunda, PACAP exerts a large array of biological effects in the brain, pituitary, adrenal gland, and ovary, suggesting that, in amphibians as in mammals, PACAP may act as neurotrophic factor, a neurotransmitter and a neurohormone.

Ontogeny of pituitary adenylate cyclase-activating polypeptide (PACAP) in the frog (Rana ridibunda) tadpole brain: immunohistochemical localization and biochemical characterization.

The anatomic distribution and biochemical characteristics of the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) were investigated in the central nervous system of the frog, Rana ridibunda, during development. Three to four days after hatching, at stages IV-VII, PACAP-immunoreactive perikarya were detected in the dorsal thalamus within the anterior ventral area, and a few fibers were found in the medial pallium. Positive cell bodies were first observed in the hypothalamus at stages VIII-IX, at the level of the dorsal and ventral infundibular nuclei. In these regions, the number of positive perikarya increased during ontogeny. In tadpoles, during the mid- and late premetamorphosis, a more complex organization of the PACAP-immunoreactive system was found in the thalamus with the appearance, at stages IX-XII, of two additional groups of positive neurons in the ventrolateral area and posterocentral nucleus. At stages XIII-XVIII of larval development and subsequent larval stages, PACAP-immunoreactive fibers were found in the median eminence. In newly metamorphosed animals, several additional groups of positive perikarya appeared in the medial pallium, the preoptic nucleus, the torus semicircularis, the tegmentum of the mesencephalon, and the cerebellum. The immunoreactive peptide contained in the tadpole brain was characterized by high performance liquid chromatography analysis combined with radioimmunoassay quantification. At all stages investigated, the predominant form of PACAP-immunoreactive material coeluted with synthetic frog PACAP38. The occurrence of PACAP soon after hatching indicates that the peptide may exert neurotrophic activities. The existence of immunoreactive elements in several thalamic regions at mid- and late premetamorphic stages suggests that PACAP may act as a neurotransmitter, neuromodulator, or both, during ontogenesis. Finally, the presence of PACAP-immunoreactive perikarya in hypothalamic nuclei and nerve fibers in the median eminence supports the view that PACAP may play a role in the control of pituitary hormone secretion during larval development.

Organization of vasoactive intestinal peptide-like immunoreactive system in the brain, olfactory organ and retina of the zebrafish, Danio rerio, during development.

The localization of vasoactive intestinal peptide (VIP)-like immunoreactivity was investigated in the brain, olfactory system and retina of the zebrafish, Danio rerio, during development and in juvenile specimens, by using the indirect immunofluorescence and the peroxidase-antiperoxidase methods. In 24 h post fertilization (hpf) embryos, VIP-like immunoreactive cells were present in the olfactory pit, the retina, and several regions of the brain, including the dorsal telencephalon, the diencephalon, the tegmentum of the mesencephalon, the caudal rhombencephalon and the anterior pituitary. In 48 hpf embryos, additional VIP-like immunoreactive cell bodies were found in the ventral telencephalon, whereas in the diencephalon VIP-like immunopositive cells were more concentrated within the ventro-caudal hypothalamus. During the 7 day larval period, a dense plexus of VIP-like immunoreactive fibers first appeared in the olfactory bulbs. In 15-day-old larvae, two new groups of positive cells were observed in the periventricular preoptic nucleus and in the dorsal rhombencephalon. In 1 month/2 months old animals, VIP-like immunoreactive elements were confined to the olfactory organ, the olfactory bulbs, the periventricular preoptic nucleus and the pituitary, pars distalis. At 3 months stage, a large number of cells was observed in the periventricular preoptic nucleus. Western immunoblot analysis confirmed that VIP-like peptides, with molecular weight similar to that of synthetic VIP, are present early during the development of zebrafish. These results show that VIP-like immunoreactive structures appear early during ontogeny both in the olfactory pit, retina and brain. Transient expression of positive cells was found in the retina, telencephalon, diencephalon and brainstem. The location of VIP-like immunoreactivity indicates that, during development, VIP could be involved in several neuromodulatory functions, including the processing of visual and olfactory informations, as well as growth or survival promotion activities. The presence of VIP-like immunopositive cells in the pituitary, pars distalis, suggest that, during development, VIP may influence the secretion of pituitary hormones.

Fos localization in cytosolic and nuclear compartments in neurones of the frog, Rana esculenta, brain: an analysis carried out in parallel with GnRH molecular forms.

C-fos activity was determined in the brain of the frog, Rana esculenta, during the annual sexual cycle. The localization of GnRH molecular forms (mammalian- and chicken-GnRHII) was also carried out to determine whether or not the proto-oncogene and the peptides showed a functional relationship. Northern blot analysis of total RNA revealed the presence of a single strong signal of c-fos like mRNA of 1.9 Kb during February and April. This was followed by expression of c-Fos protein (Fos) in several brain areas during March and July shown by immunocytochemistry. In particular, the olfactory region, the lateral and medial pallium, the nucleus lateralis septi, the ventral striatum, the caudal region of the anterior preoptic area, the suprachiasmatic nucleus, the ventral thalamus, tori semicircularis and ependymal layers of the tectum were immunostained. There was no overlap between Fos immunoreactive perikarya and GnRH immunoreactive perikarya (e.g. gonadotrophin-releasing hormone (GnRH) in the rostral part and Fos in the caudal region of the anterior preoptic area). Interestingly, a cytoplasmic localization of Fos was also observed by immunocytochemistry and gel retardation experiments supported this observation. Cytoplasmic extracts from September-October animals bound the AP1 oligonucleotide. The complex was not available in the nuclear extracts from the same preparation, suggesting that, besides Fos, Jun products were also present. Conversely, nuclear but not cytosolic binding was detected in the brain of animals collected in July. In conclusion, we show that Fos and GnRH activity does not correlate in the frog brain and, for the first time in a vertebrate species, we give evidence of a cytoplasmic AP1 complex in neuronal cells.

Distribution of vasoactive intestinal peptide-like immunoreactivity in the brain and pituitary of the frog (Rana esculenta) during development.

The localization of vasoactive intestinal peptide (VIP)-like immunoreactive (ir) elements was investigated in the brain of the anuran amphibian, Rana esculenta, during development. Using an antiserum raised against the porcine VIP, ir cell bodies and fibers were observed in the forebrain of tadpoles a few days after hatching. During early premetamorphosis, ir perikarya were distributed in the ventral infundibular nucleus of the hypothalamus and in the posterocentral nucleus of the thalamus. Labeled fibers were detected in the olfactory bulbs and in the hypothalamus. In these larvae, furthermore, several VIP-ir cells were found in the pars distalis of the pituitary and there were ir fibers in the pars nervosa. In tadpoles at stages VIII-IX, a new group of VIP-labeled neurons was observed in the dorsal part of the infundibular nucleus. In other brain regions, the distribution of the immunoreactivity was similar to that described in the earliest stages, i.e., IV-VII. During mid-premetamorphosis, stages X-XII of development, an additional set of ir perikarya appeared in the ventrolateral area of the thalamus. During late premetamorphosis, stages XIII-XVIII, the organization of VIP-like immunoreactivity was more complex and its distribution more widespread. Two new groups of ir cell bodies appeared, one in the preoptic nucleus and another in the anteroventral area of the thalamus, and for the first time, VIP immunoreactivity was observed in the median eminence. This distribution pattern persisted through to the prometamorphic, four-limb stage. Strikingly, no VIP-ir elements were observed anywhere in the mid- and hindbrain. The present results indicate that a VIP-like ir peptide may be involved in the processing of olfactory information or may act as a neurohormone, hypophysiotropic factor, and neuromodulator in the brain of R. esculenta during development.

Distribution of somatostatin-like immunoreactivity in the brain of the frog, Rana esculenta, during development.

The anatomical distribution of somatostatin-like immunoreactivity in the central nervous system of the frog, Rana esculenta, during development and in juvenile specimens was investigated by indirect immunofluorescence. Soon after hatching, at stages II-III, somatostatin-like immunoreactive structures were found in the preoptic-median eminence complex. In stage VI tadpoles, new groups of immunopositive perikarya and nerve fibers appeared in the diencephalon, within the ventral infundibular nucleus and in the ventral area of the thalamus, as well as in the medial pallium. In stages XII-XIV of development, immunopositive perikarya were also present in the dorsal infundibular nucleus of the hypothalamus and ventrolateral area of the thalamus. A small group of somatostatin-like immunoreactive neurons appeared in the posteroventral nucleus of the rhombencephalon. However, these neurons were not seen in later stages of development. Tadpoles in stages XVIII, XXI-XXII and in juveniles were characterized by a wider distribution of immunoreactive cell bodies and fibers in the pallium. New groups of immunoreactive neurons were found in the dorsal and lateral pallium. The presence of positive perikarya in the lateral pallium is a transient expression found only in these stages. The organization of the somatostatinergic system was most complex during the metamorphic climax, with the appearance of positive cell bodies in the posterocentralis area of the thalamus, and in juvenile animals with the presence of perikarya in the ventral part of the medial pallium and within the central grey rhombencephali. In contrast to the adult frog, somatostatin neurons were not observed in the mesencephalon of tadpoles and juveniles.

Detection of GnRH molecular forms in brains and gonads of the crested newt, Triturus carnifex.

Gonadotrophin-releasing hormone (GnRH) immunoreactivity is detectable in the brain, ovary, and testis of the newt, Triturus carnifex, collected during February (reproductive phase), May, and July (nonreproductive phase). In the brain of May animals, chicken GnRH-II positive cell bodies are located within the terminal nerve, the anterior preoptic area, and the preoptic nucleus, which appears to be devoid of immunoreactive mammalian GnRH cell bodies. During February and July, both chicken GnRH-II and mammalian GnRH are detected only within the terminal nerve and anterior preoptic area. Generally, in the reproductive as well as the nonreproductive periods, chicken GnRH-II fibers are widely distributed in the brain; however, the distribution of fibers of both molecular forms suggests that they exert hypophysiotropic activity. High-pressure liquid chromatography (HPLC) coupled with radioimmunoassay indicates the presence of an early-eluting GnRH peak in brains and gonads but not in plasma. Using chicken GnRH-II antiserum, immunoreactivity is observed in spermatocytes, spermatozoa, and the external theca layer. Seasonal changes of the GnRH-like material are observed in both sexes, and its high concentration detectable during February is in good correlation with the timing of reproduction.

Localization of GnRH molecular forms in the brain, pituitary, and testis of the frog, Rana esculenta.

In the amphibian brain four molecular forms of GnRH have been identified so far: mammalian GnRH (m- and hydroxyproline9m-), chicken II GnRH (cII), and a salmon (s) GnRH-like peptide. In Rana esculenta, cII- and s-GnRH-like molecules have been partially characterized in the brain extracts using HPLC combined with radioimmunoassay. Moreover, since cII-GnRH-like material has been detected in Rana esculenta testis, the present study describes the localization of the above peptides in the brain and testis of the frog. Immunoreactive cII-GnRH and m-GnRH neurons and fibers were identified in the anterior preoptic area (APOA) and in the median septal area (MSA). A population of cells located on the dorsal side of the caudal preoptic region was also stained. Immunopositive fibers were seen to overlap the median eminence before ending within the pars nervosa. Moreover, densely packed fibers made close contact with the vascular complex in the median eminence. Conversely, immunoreactive s-GnRH-like material was absent in APOA and MSA, but weakly scattered elements were detected by the anti-s-GnRH serum in the dorsal side of the caudal preoptic region. Using m-GnRH antiserum, a strong immunopositivity was observed in the median eminence but not within the pars nervosa, indicating that, besides cII-GnRH and s-GnRH-like material, also m-GnRH-like material is present in Rana esculenta brain. In the testis, cells of the interstitial and germinal compartment were detected by anti-cII-GnRH during different periods of the annual cycle. In particular, in October and February interstitial tissue was intensely stained, coinciding with periods of increased androgen production and the onset of the new spermatogenic wave, respectively.

Localization and characterization of gonadotropin-releasing hormones in the brain, gonads, and plasma of a dipnoi (lungfish, Protopterus annectens).

Two molecular forms of GnRH (chicken GnRH II and a second variant) are present in the brains of species from all the major vertebrate groups. Their differential distribution in the brain and temporal expression during development suggests that have different functional roles. We investigated the nature of GnRH molecular forms in the brain, plasma, testis, and ovary of adult and juvenile lungfish (Protopterus annectens), using high performance liquid chromatography and radioimmunoassay with specific GnRH antisera. In the brain of adult and juvenile lungfish, two peptides with identical chromatographic and immunologic properties to mammalian GnRH and chicken GnRH II were detected. Chicken GnRH II predominated in both the adult and juvenile brain, and the percentage of chicken GnRH II relative to mammalian GnRH was greater in the juvenile brain. In the plasma, only mammalian GnRH was present. Immunoreactive GnRH was not detected in the testis and ovary. Chicken GnRH II and mammalian GnRH were found in the cells of the preoptic nucleus and in the ganglion of the nervus terminalis. Fibers were seen in the ventral hypothalamus, and chicken GnRH II immunoreactivity was detected within the neural lobe of the pituitary. The finding of chicken GnRH II in a sarcopterygian fish adds further support to our hypothesis that this ubiquitous structural variant is highly conserved and likely to have an important functional role. Mammalian GnRH, previously described in several early-evolved actinopterygian fish, also has a fairly widespread distribution and early evolutionary origin. The immunocytochemical distribution of mammalian GnRH and chicken GnRH II fibers in the lungfish brain suggests that both forms are hypophysiotropic. In addition, the presence of mammalian GnRH in the plasma of the lungfish suggests that this molecular form of GnRH has a hypophysiotropic function reaching target organs (pituitary and gonads) via the general circulation.

Nature and distribution of gonadotropin-releasing hormone (GnRH) in the brain, and GnRH and GnRH binding activity in serum of the spotted dogfish Scyliorhinus canicula.

The distribution of different molecular forms of gonadotropin-releasing hormone (GnRH) in the brain and serum of the spotted dogfish, Scyliorhinus canicula, was investigated by an indirect immunofluorescence method, using antisera against salmon (s-), chicken-II (cII-) and mammalian (m-) GnRHs, and by reverse-phase high-performance liquid chromatography (RP-HPLC) coupled with radioimmunoassays. Five GnRH molecular forms were demonstrated on the basis of the retention time in the RP-HPLC system. The characteristics of four of these GnRH peptides are consistent with those of m-, cII-, dogfish (df-), and sGnRH. The fifth form appears to be novel. Immunoreactive sGnRH structures were confined to the diencephalon; whereas cIIGnRH and mGnRH were found in the telencephalon and diencephalon. cIIGnRH- and dfGnRH-like molecules were detected in the serum. Moreover, a specific, low-affinity GnRH binding protein (GnRH-BP) was found in the serum of the spotted dogfish. The binding of [125I]sGnRHA to the serum GnRH-BP was dependent on incubation time, equilibrium being reached within 1 hr at 4 degrees; binding was rapid and completely reversible. Scatchard analysis yielded a linear plot with a Kd of 7.9 x 10(-7) M. The presence of a GnRH-BP in spotted dogfish serum suggests a probable action of GnRH via the general circulation.

Detection and localization of gonadotrophin-releasing hormone (GnRH)-like material in the frog, Rana esculenta, ovary.

GnRH-like material has been identified using HPLC followed by RIA in the ovary of Rana esculenta. During the reproductive cycle three immunoreactive GnRH peaks were eluted. One of them coeluted with s-GnRH, the other two forms between GnRH and cII-GnRH. During the recovery phase s-GnRH immunoreactivity disappears. By immunocytochemistry, cII-GnRH immunostaining was localized to granulosa cells while s-GnRH was present in the perinuclear zone of the oocytes.

Presence and steroidogenetic activity of beta-endorphin in the ovary of the lizard, Podarcis s. sicula raf.

In mammals, proopiomelanocortin (POMC)-related peptides are involved in reproductive processes at both the hypothalamopituitary and ovarian levels. Through immunocytochemical and physiological in vitro studies, evidence for a diffuse POMC-related opioid system in the lizard Podarcis s. sicula is provided. In the lizard ovary, beta-endorphin (beta-EP)-like immunoreactive cells were observed within the granulosa layer; the immunoresponse showed seasonal variation, being most pronounced in the winter ovary. HPLC followed by immunoassay showed that acetyl beta-EP is the main form of POMC-related peptide in both pituitary and ovary. In vitro studies showed that picomolar amounts of beta-EP stimulate follicular estrogen production during both the reproductive and winter phases; induction was found to be higher in the reproductive phase. The data reported here provide evidence for the physiological role played by beta-EP in the reproductive function of Podarcis s. sicula via induction of ovarian production of estradiol-17 beta, which is the main factor responsible for the vitellogenic process.

Immunocytochemical identification of some regulatory peptides (gastrin, gastrin-releasing peptide, neurotensin and vasoactive intestinal polypeptide) in the Harderian gland of the green frog, Rana esculenta.

The presence and distribution of gastrin-, gastrin-releasing peptide-, neurotensin- and vasoactive intestinal polypeptide-like immunoreactivity in the Harderian gland of Rana esculenta were studied at different times of the annual cycle. Gastrin-releasing peptide, neurotensin and vasoactive intestinal polypeptide-like substances were found either in the glandular cells, or in the nerve fibers surrounding the glandular acini. Gastrin-like immunoreactivity was confined to the glandular cells. The immunoreactivity varied during the annual cycle, with the greatest concentration being noted during the recovery phase of glandular secretory activity.

Ovarian opioids and the reproductive cycle of the frog Rana esculenta.

In mammals, proopiomelanocortin-related peptides are involved in reproductive processes both at the hypothalamo-pituitary and ovarian levels. Using immunocytochemical, biochemical and physiological "in vitro" studies, we provide here evidence for a diffuse POMC-related opioid system in the frog Rana esculenta. Ovarian beta-endorphin (beta-EP) is expressed in thecal cells and changes during the reproductive cycle in an inverse relationship with follicular development. Seasonal changes in the ovary are different to those in the brain or in the pituitary. The ratio of acetylated vs native beta-EP in the ovary also changes over the reproductive period, affecting the biological activity of the peptide. During both the reproductive spring period and the summer post-reproductive phase pMol amounts of beta-EP stimulate follicular androgen secretion in vitro, in a naloxone-reversible way. In either period, an inhibition of estradiol, possibly mediated via other factors, is the result of opioid action. In conclusion, these data demonstrate for the first time the widespread presence of beta-EP-related peptides in the frog Rana esculenta. Both immunocytochemical and biochemical evidence, as well as in vitro responses, support a physiological role for beta-EP in ovarian seasonality during the reproductive cycle of this amphibian.

Immunohistochemical mapping of galanin-like immunoreactivity in the brain of the dogfish Scyliorhinus canicula.

The distribution of galanin-like immunoreactivity in the brain of the dogfish Scyliorhinus canicula was investigated using the indirect immunofluorescence technique. In the telencephalon, positive cells and fibers were located in the mid-caudal part of the area superficialis basalis, the n. septi caudoventralis and in the n. interstitialis commissurae anterioris. Most of the galanin-containing neurons observed in the hypothalamus were located in the magnocellular preoptic nucleus. Positive perikarya were also found in the n. lobi lateralis hypothalami and in the n. lateralis tuberis. A dense network of positive nerve processes was noted in the caudal part of the median eminence. In the dorso-caudal part of the diencephalon numerous immunoreactive neurons were seen in the recessus posterioris. A large bundle of galanin-containing fibers, which divided in two branches, was observed in the basal midbrain tegmentum. The widespread distribution of galanin-like material suggests that, in the dogfish, galanin may be involved in various brain functions including neuroendocrine regulations.

Melanin-concentrating hormone (MCH) immunoreactivity in the brain and pituitary of the dogfish Scyliorhinus canicula. Colocalization with alpha-melanocyte-stimulating hormone (alpha-MSH) in hypothalamic neurons.

The distribution of melanin-concentrating hormone (MCH) in the central nervous system of the dogfish Scyliorhinus canicula was determined by indirect immunofluorescence and peroxidase-anti-peroxidase techniques, using an antiserum raised against synthetic salmon MCH. Three groups of MCH-positive cell bodies were localized in the posterior hypothalamus. The most prominent cell group was detected in the nucleus sacci vasculosi. Scattered MCH-immunoreactive cells were observed in the nucleus tuberculi posterioris and in the nucleus lateralis tuberis. At the pituitary level, the caudal part of the median lobe of the pars distalis contained strongly MCH-positive perikarya. Some of these cells were liquor-contacting-type. Immunoreactive fibers originating from the hypothalamic perikarya projected throughout the dorsal wall of the posterior hypothalamus. Positive fibers were also detected within the thalamus and the central gray of the mesencephalon. The distribution of MCH-containing neurons was compared to that of alpha-MSH-immunoreactive elements using consecutive, 5-micron thick sections. Both MCH- and alpha-MSH-immunoreactive peptides were found in the same neurons of the nucleus sacci vasculosi. These data suggest that MCH and alpha-MSH, two neuropeptides which exert antagonistic activities on skin melanophores, may also act in a coordinate manner in the central nervous system of cartilaginous fish.

Sauvagine/urotensin I-like immunoreactivity in the brain of the dogfish, Scyliorhinus canicula.

The localization of a sauvagine (SV)/urotensin I (UI)-like material in the brain of the dogfish, Scyliorhinus canicula, was studied by immunohistochemical techniques, employing an antiserum raised in rabbit against synthetic SV which widely cross-reacts with UI. Positive cell bodies and nerve fibers were identified in the dorsocaudal hypothalamic region of the tuberculum posterius, in the nucleus sacci vasculosi and nucleus tuberculi posterioris. A dense network of immunoreactive axons was shown in the whole tuberculum posterius. These findings support the view that SV/UI-like peptides may be involved in neuromodulatory functions throughout the brain of cartilaginous fish.

beta-Endorphin-like immunoreactivity in the brain of the lizard, Lacerta muralis.

Using immunocytochemical methods, a beta-endorphin-like immunoreactive substance was identified in the brain of the lizard Lacerta muralis. beta-Endorphin-like neurons were observed in the dorsal posterior part of the paraventricular nucleus and in the caudal region of the nucleus ventromedialis hypothalami. beta-Endorphin-like immunoreactive fibers were also detected in the median eminence. Another cell group displaying beta-endorphin-like immunoreactivity was found in both subdivisions of the oculomotor nucleus and in the periaqueductal gray of the mesencephalon. In addition, a beta-endorphin-like immunoreaction was observed in the perikarya of the Purkinje cells and in their axonal processes. These patterns of immunoreactivity were completely abolished when a specific antiserum was absorbed with its corresponding antigen or with beta-lipotropin. These control tests suggest that the immunoreaction might correspond to a beta-endorphin- or lipotropin-like reaction. The results are discussed in relation to the possibility that a beta-endorphin-like peptide may be involved in hypophysial regulation or neuromodulator activity in the brain of the lizard L. muralis.

Occurrence of beta-endorphin-like immunoreactivity in the brain of the teleost, Boops boops.

By immunocytochemical methods the present study describes beta-endorphin-like immunoreactive substance in the brain of Boops boops. Beta-Endorphin-like neurons and fibers were detected in both dorsal and ventral components of the preoptic nucleus and in the nucleus lateralis tuberis. This localization has been discussed in relation to the presence, in the same area, of a well-defined neurosecretory system involved in hypophysial regulation. A beta-endorphin-like immunoreaction was also detected in the Purkinje cells and in processes within the cerebellum molecular layer. Although this last finding remains enigmatic it may suggest a neuromodulatory activity for cerebellum beta-endorphin-like substance. No immunoreaction was observed when the specific antiserum was absorbed with corresponding antigen and with beta-LPH. These tests led to the conclusion that the immunostaining reaction might correspond to a beta-endorphin- or lipotropin-like reaction. Further, the present results show the phylogenetic antiquity of a beta-endorphinergic or lipotropinergic system in the brain, with a stable evolutionary history as a hypophysial regulatory factor or neuromodulatory agent.