E. Campantico

Expression and distribution of CB1 cannabinoid receptors in the central nervous system of the African cichlid fish Pelvicachromis pulcher

Neuroanatomical investigation of the cannabinoid system in a lower vertebrate group such as teleost fishes might improve our understanding of the physiological role of such a signaling system. In the present study, the expression of a CB1 cannabinoid receptor has been demonstrated in the CNS of a teleost fish, the cichlid Pelvicachromis pulcher. Moreover, CB1‐like immunoreactivity has been analyzed by using a purified antibody against the CB1 receptor amino‐terminus. Immunostained neurons and varicosities were found through the telencephalon as well as in the preoptic area and lateral infundibular lobes of the hypothalamus. Stained cells were observed in the pituitary gland. Several cell bodies and nerve terminals containing an intense CB1‐like immunoreactivity were found in the pretectal central nucleus and posterior tuberculum, both lying in a transitional region between diencephalon and mesencephalon. In the brainstem, the CB1 immunopositivity was more restricted than in the prosencephalon, with the exception of some large, intensely immunopositive nerve cells within the dorsal mesencephalic tegmentum, possibly motor neurons of the third cranial nerve. In the cerebellum, among a majority of immunonegative granule cells, a subset of them was immunostained. Some positive Purkinje cells were also observed. In the spinal cord, ventral gray matter, several α‐motoneurons were stained. Similarities to and discrepancies from the CB1 receptor distributions in other vertebrate CNS are discussed, paying particular attention to the abundant CB1 immunoreactivity observed in the area encompassing the pretectum and glomerular nucleus, which is characterized by a peculiar differentiation in bony fishes. J. Comp. Neurol. 485:293–303, 2005.

On the early appearance of arginase activity in the liver of Bufo bufo larvae after prolactin treatment

Abstract In the liver of prolactin-treated Bufo bufo larvae, thyroid-dependent arginase activity is seen to arise at earlier stages than in controls. This finding lends further support to our assumption that prolactin induces activation rather than thyroid inhibition, as previously suggested by the cytological pattern of hyperactivity and enhanced thyroidal radioiodine uptake in prolactin-treated larvae at advanced metamorphic stages.

Are the cannabinoids involved in bony fish reproduction

Abstract: Following the discovery of two CB1 genes in the fish Fugu rubripes, investigations on the phylogeny of endocannabinoids have indicated that this system is highly conserved. Our study demonstrated that CB1 receptors are expressed in the CNS and gonads of two teleosts, Carassius auratus and Pelvicachromis pulcher, and they show a high percentage of sequence identity with Fugu rubripes CB1A and Danio rerio CB1. By means of immunohistochemistry for CB1, sGnRH, and TH, we found a codistribution of these signaling molecules in the basal telencephalon/preoptic area, which are key centers for gonadotropic regulation. We therefore suggest that endocannabinoids are possibly involved in modulating fish reproduction at both the central and peripheral levels.

Effects of prolactin on arginase activity in the liver of Bufo bufo larvae under different experimental conditions

Abstract Exogenous thyroxine promotes the early appearance of arginase activity in the liver of normal and hypophysectomized Bufo bufo larvae. This effect does not seem to be exerted by endogenous prolactin (or a prolactinlike growth factor) which is secreted in higher amounts in radiothyroidectomized larvae as compared to normal larvae. Likewise, no arginase activity was recorded in the liver of thyroidectomized larvae after daily injection of 0.3 IU of mammalian prolactin. Since under the same conditions mammalian prolactin was seen to promote an early appearance of arginase in the liver of normal larvae, it is postulated that prolactin action is mediated by thyroidal stimulation.

Biochemical data on some organs from normal or prolactin-treated Xenopus laevis (Daudin) adults reared in fresh and in salt water ☆

Abstract The effects of salinity and of prolactin treatment on urea synthesis in the liver, and on the shift from ammonotelic to ureotelic excretion, were studied in adult Xenopus laevis . The activity of both arginase and urea synthesis in the liver increased in the animals reared in salt water. This rise is reduced by prolactin treatment. In addition, estimation of the activity of alkaline phosphomonoesterase (taken as a test of the functional condition of the adrenal glands) showed that it decreases in salt water animals. This decrease was more pronounced after prolactin treatment. Increase in the level of sodium in the muscle tissue, which is connected with the level of this ion in the blood, occurred in the salt water animals and was further enhanced by prolactin treatment.

Biochemical responses elicited in normal or prolactin-treated Xenopus laevis (Daudin) specimens by environmental changes

Abstract 1. 1. Biochemical responses to environmental changes were recorded in normal or prolactin-treated Xenopus laevis specimens. 2. 2. Maintenance on moist moss elicits the urea cycle activation, while prolactin does not; hepatic ammonia concentration decreases in both cases. 3. 3. In the animals reared on moist moss the activity of intestine alkaline phosphomonoesterase is enhanced, but drops significantly after prolactin treatment; this enzyme is not significantly reduced in fresh-water prolactintreated animals. 4. 4. Both rearing on moist moss and prolactin treatment elicit sodium gain in the muscle; permanence on moist moss leads to potassium loss which is abolished by prolactin.

Identification by immunofluorescence of prolactin- and somatotrophin-producing cells in the pituitary gland of the tree frog Hyla arborea

The indirect immunofluorescence procedure was used to localize prolactin (PRL)- and somatotrophin (STH)- producing cells in the pituitary distal lobe from Hyla arborea adult specimens. The following mammalian antisera were employed: rabbit anti-ovine PRL, antibovine PRL, anti-human PRL, anti-rat PRL, anti-ovine STH, anti-bovine STH, anti-human STH; monkey anti-rat STH. Immunocytochemical staining was suppressed by solid phase absorption of both anti-PRL and anti-STH with the specific antigen. Absorption of anti-PRL with STH and of anti-STH with PRL did not appreciably affect immunocytochemical staining. Treatment with the two antisera revealed two different reactive cell types, both acidophils. Using PRL antisera a strong fluorescence was found in the large acidophils located chiefly in the rostro-central and ventral areas of the distal lobe sagittal sections. A somewhat weaker fluorescence was observed using STH antisera in the fewer, small acidophils mostly concentrated in the dorso-caudal region and only sparsely scattered in the other areas of the pars distalis. Strikingly, the overall pattern of localization shown by the two cell types is similar to their already known distribution in the pituitary distal lobe of some other species of urodele and anuran amphibians.

Interplay of the endocannabinoid system with neuropeptide Y and corticotropin-releasing factor in the goldfish forebrain.

Based on pharmacological, behavioral, and neuroanatomical studies, the endocannabinoid system appears to be pivotal in some neuroendocrine mechanisms, such as modulation of vertebrate reproduction, stress, and food intake. The present study aimed to investigate the involvement of the endocannabinoid system in the control of the feeding response in the goldfish. By means of immunohistochemistry techniques, using anti‐CB1 cannabinoid receptor, anti‐corticotropin‐releasing factor (CRF), and anti‐neuropeptide Y (NPY) antisera on brain sections of Carassius auratus, we found a topographical co‐distribution of the three signaling molecules through the preoptic area and posterior lobes of the hypothalamus and even a co‐localization of CB1 and NPY in the telencephalon. Previous results have shown that food deprivation in goldfish is accompanied by a significant increase of anandamide (AEA) levels in the telencephalon and AEA causes a dose‐dependent effect on food intake. We have thus investigated the possible influence of intraperitoneal AEA injections on NPY expression. Our results indicate an interplay between the endocannabinoid system and orexigenic and anorexigenic molecules, such as NPY and, possibly, CRF.

Immunocytochemical identification of growth hormone- and prolactin-producing cells in the hypophysis of the newt Triturus cristatus carnifex Laur

Single indirect immunocytochemical methods (immunofluorescence, PAP, and ABC) and double sequential staining (ABC followed by immunofluorescence) were used to localize GH- and PRL-producing cells in the pituitary distal lobe from Triturus cristatus. The following antisera were employed: rabbit anti-ovine PRL, anti-Rana catesbeiana PRL, anti-ovine GH, anti-bovine GH, and monkey anti-rat GH. A cell population corresponding to type-2 acidophils localized in the dorsal and central region, under the intermediate lobe, immunoreacted with GH antisera. Both ovine and bullfrog PRL antisera labeled a large cell population, corresponding to type-1 acidophils, predominantly localized in the ventral anterior two-thirds of the gland. The pattern of localization shown by the two cell types, although consistent with the majority of data on adult amphibians, disproves the findings obtained on the same species by other authors.

Goldfish CB1 mRNA expression is affected by fasting and anandamide administration.

The endocannabinoid system has a well-documented pivotal role in the control of mammalian feeding response; nevertheless, some evidence is available regarding a similar role in nonmammalian vertebrates and invertebrates. As in the bonyfish Carassius auratus, CB1 cannabinoid receptors are abundant in brain regions involved in the control of food intake, and fasting affects endocannabinoid levels, in this study the effects of food deprivation and anandamide administration on CB1 expression were evaluated. Fasting led to a time-dependent increase of CB1 mRNA levels in the forebrain, an effect reversed by refeeding. Furthermore, the administration of exogenous anandamide reduced CB1 expression in food-deprived goldfish. Our results support the involvement of CB1 receptors in the control of energy intake in nonmammalian vertebrates.