Pituitary adenylate cyclase-activating polypeptide type 1 (PAC1) receptor is expressed during embryonic development of the earthworm.

Pituitary adenylate cyclase activating polypeptide (PACAP)-like molecules have been shown to be present in cocoon albumin and in Eisenia fetida embryos at an early developmental stage (E1) by immunocytochemistry and radioimmunoassay. Here, we focus on detecting the stage at which PAC1 receptor (PAC1R)-like immunoreactivity first appears in germinal layers and structures, e.g., various parts of the central nervous system (CNS), in developing earthworm embryos. PAC1R-like immunoreactivity was revealed by Western blot and Far Western blot as early as the E2 developmental stage, occurring in the ectoderm and later in specific neurons of the developing CNS. Labeled CNS neurons were first seen in the supraesophageal ganglion (brain) and subsequently in the subesophageal and ventral nerve cord ganglia. Ultrastructurally, PAC1Rs were located mainly on plasma membranes and intracellular membranes, especially on cisternae of the endoplasmic reticulum. Therefore, PACAP-like compounds probably influence the differentiation of germinal layers (at least the ectoderm) and of some neurons and might act as signaling molecules during earthworm embryonic development.

Influence of PACAP on oxidative stress and tissue injury following small-bowel autotransplantation.

Tissue injury caused by cold preservation and reperfusion remains an unsolved problem during small-bowel transplantation. Pituitary adenylate cyclase-activating polypeptide (PACAP) is present and plays a central role in the intestinal physiology. This study investigated effect of PACAP-38 on the oxidative stress and tissue damage in autotransplanted intestine. Sham-operated, ischemia/reperfusion, and autotransplanted groups were established in Wistar rats. In ischemia/reperfusion groups, 1 h (group A), 2 h (group B), and 3 h (group C) ischemia followed by 3 h of reperfusion was applied. In autotransplanted groups, total orthotopic intestinal autotransplantation was performed. Grafts were preserved in University of Wisconsin (UW) solution and in UW containing 30 microg PACAP-38 for 1, 2, 3, and 6 h. Reperfusion lasted 3 h in all groups. Endogenous PACAP-38 concentration was measured by radioimmunoassay. To determine oxidative stress parameters, malondialdehyde, reduced glutathione, and superoxide dismutase were measured in tissue samples. Tissue damage was analyzed by qualitative and quantitative methods on hematoxylin/eosin-stained sections. Concentration of endogenous PACAP-38 significantly decreased in groups B and C compared to sham-operated group. Preservation solution containing PACAP-38 ameliorated bowel tissue oxidative injury induced by cold ischemia and reperfusion. Histological results showed that preservation caused destruction of the mucous, submucous, and muscular layers, which were further deteriorated by the end of reperfusion. In contrast, PACAP-38 significantly protected the intestinal structure. Ischemia/reperfusion decreased the endogenous PACAP-38 concentration in the intestinal tissue. Administration of PACAP-38 mitigated the oxidative injury and histological lesions in small-bowel autotransplantation model.

Effects of PACAP on survival and renal morphology in rats subjected to renal ischemia/reperfusion.

Pituitary adenylate cyclase activating polypeptide (PACAP) occurs and exerts a variety of biological functions in the nervous system and in the peripheral organs, including the urinary system. PACAP has protective effects against myeloma kidney injury and renal ischemia. Ischemia/reperfusion injury of the kidney is a major clinical problem, and based on the protective effects of PACAP in cerebral and cardiomyocyte ischemia, the aim of the present study was to evaluate the effects of a single intravenous PACAP injection on the survival and renal morphology after varying times of ischemia. Rats were subjected to renal artery clamping for 15, 30, 45, 60, or 75 min followed by reperfusion. PACAP (100 microg) was administered intravenously before arterial clamping. We found that a 15- or 30-min renal ischemia led to no renal dysfunction, and the kidneys showed normal appearance with no difference between PACAP- and saline-treated groups. Control rats with 45 min of ischemia had increased premature death rate and showed multifocal acute tubular atrophy, while a 60-min ischemia led to death of all control animals within a few days displaying severe, multifocal Grade II tubular atrophy. In contrast, all PACAP-treated animals survived with subtle morphological changes after the 45-min ischemia. After the 60-min ischemia, death rate was significantly lower in PACAP-treated rats compared to controls, and animals showed subtle focal tubular alteration. A 75-min ischemia was not performable in controls because of deaths before the termination of ischemia. PACAP-treated rats survived longer, but they also died after 5-10 days exhibiting severe focal tubular atrophy. In summary, our results clearly show that PACAP is able to prolong the renal ischemic time, decrease mortality, and attenuate tubular degeneration after renal ischemia.

PACAP has anti-apoptotic effect in the salivary gland of an invertebrate species, Helix pomatia.

Pituitary adenylate cyclase activating polypeptide (PACAP) shows a remarkable sequence similarity among species and several studies provide evidence that the functions of PACAP have also been conserved among vertebrate species. Relatively little is known about its presence and functions in invertebrates. The aim of the present study was to investigate whether the well-known anti-apoptotic effect of PACAP can also be demonstrated in invertebrates. This effect was studied in the salivary gland of a molluscan species, Helix pomatia. In this work, we first showed the presence of PACAP-like immunoreactivity in the Helix salivary gland by means of immunohistochemistry. Radioimmunoassay measurements showed that PACAP38-like immunoreactivity dominated in the salivary gland of both active and inactive snails and its concentration was higher in active than in inactive animals in contrast to PACAP27-like immunoreactivity, which did not show activity-dependent changes. PACAP induced a significant elevation of cAMP level in salivary gland extracts. Application of apoptosis-inducing agents, dopamine and colchicine, led to a marked increase in the number of terminal uridine deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cells in the salivary gland, which was significantly attenuated by PACAP treatment. In a similar manner, the number of caspase-positive cells was reduced after co-application of dopamine and PACAP. Taken together, the data indicate that PACAP activates cAMP in a molluscan species and we show, for the first time, that PACAP is anti-apoptotic in the invertebrate Helix pomatia.

Investigation of the effects of PACAP on the composition of tear and endolymph proteins.

Pituitary adenylate cyclase activating polypeptide (PACAP) is widely distributed in ocular tissues, including the lacrimal gland. PACAP has been shown to influence the activity of several exocrine glands, but its effects on the composition of the tear film are not known yet. Similarly, the presence of PACAP has already been shown in the inner ear, but it is not known whether PACAP influences the composition of the endolymph. The aim of the present study was to investigate whether systemic injection of PACAP has any modulatory effects on the protein composition of the tear film and endolymph using chip electrophoresis and mass spectrometry analysis. Tear and endolymph samples were collected from rats and chickens, respectively, at various time points after systemic injection of PACAP. Fluid samples were further processed for chip electrophoretic studies. No difference was found in the protein composition of the endolymph between control and PACAP-treated animals. In contrast, tear samples showed a marked difference after PACAP treatment. Proteins in the molecular range 50-70 kDa, which showed a different chip electropherogram profile in every PACAP-treated sample, were further analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. PACAP treatment induced a repression in certain keratins, while others were induced after PACAP injection. Furthermore, PACAP treatment decreased aldehyde dehydrogenase expression. The present study provides a base for further studies on the in vivo effects of PACAP on the composition of tear film. These investigations may have important clinical relevance because of the noninvasive sample collection, the correlation between tear proteins and ocular diseases, and the possible presence of biomarkers for both ophthalmological and systemic pathological conditions.

Changes in the expression of PACAP-like compounds during the embryonic development of the earthworm Eisenia fetida.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is expressed at very early stages in the vertebrate nervous system, and its functions in the embryonic development have been shown by various studies. PACAP is an extremely conserved molecule in phylogeny; however, little is known about its presence and functions in invertebrates. Our previous studies have shown the occurrence of PACAP-like immunoreactivity in the invertebrate nervous system. The aim of this study was to investigate the presence and localization of PACAP-like compounds during the embryonic development of earthworms from cocoon deposition to hatching using immunological methods (radioimmunoassay, dot blot, immunohistochemistry). PACAP-like immunoreactive compounds were detected at very early stages of the embryonic development of the earthworm Eisenia fetida. No significant changes were observed during the early stages in the developing embryo, but a marked increase occurred before hatching. In contrast, during the embryonic development, the level of PACAP-like compounds gradually decreased in cocoon fluids. Immunohistochemistry revealed the presence of PACAP-like immunoreactive cell bodies and processes in the developing body wall, prostomium, pharyngeal wall, and central nervous system. Cells located in the body wall correspond to putative progenitor cells of primary sensory cells. In the present study, we also showed that the clitellum (reproductive organ) of sexually mature worms contained significantly higher levels of PACAP-like immunoreactivity than other regions of the same animals or the clitellar region of a non-reproducing animal. In summary, these observations provide a morphological basis and suggest a role of PACAP(-like peptides) in the reproductive and developmental functions of invertebrates.

Expression of PACAP-like compounds during the caudal regeneration of the earthworm Eisenia fetida.

The regeneration of the ventral nerve cord ganglion and peripheral tissues was investigated by radioimmunoassay and immunohistochemistry in the model animal, Eisenia fetida (Annelida, Oligochaeta). It is now well-established that pituitary adenylate cyclase-activating polypeptide (PACAP) is a neurotrophic factor, playing important roles in the development of the nervous system in vertebrate animals. Based on the apparent evolutionary conservation of PACAP and on the several common mechanisms of vertebrate and invertebrate nervous regeneration, the question was raised whether PACAP has any role in the regeneration of the earthworm nervous system. As a first step, we studied the distribution, concentration, and time-course of PACAP-like immunoreactivity during caudal regeneration of both lost segments and the ventral nerve cord ganglia in E. fetida. A strong upregulation of PACAP-like immunoreactivity was observed in most tissues following injury as determined by radioimmunoassay and immunohistochemistry. Significant increases in the concentration of PACAP-like compounds were found in the body wall, alimentary canal, and in coelomocytes. The most characteristic morphological feature was the accumulation of immunolabeled neoblasts in the injured tissues, especially in the ventral nerve cord ganglion that initiates and mediates regeneration processes. Our present results show that PACAP/PACAP-like peptides accumulate in the regenerating tissues of the earthworm, suggesting trophic functions of these compounds in earthworm tissues similarly to vertebrate species.

Hyperosmotic stress-induced apoptotic signaling pathways in chondrocytes.

Articular chondrocytes have a well-developed osmoregulatory system that enables cells to survive in a constantly changing osmotic environment. However, osmotic loading exceeding that occurring under physiological conditions severely compromises chondrocyte function and leads to degenerative changes. The aim of the present study was to investigate the form of cell death and changes in apoptotic signaling pathways under hyperosmotic stress using a primary chondrocyte culture. Cell viability and apoptosis assays performed with annexin V and propidium iodide staining showed that a highly hyperosmotic medium (600 mOsm) severely reduced chondrocyte viability and led mainly to apoptotic cell death, while elevating osmotic pressure within the physiological range caused no changes compared to isosmotic conditions. Western blot analysis revealed that a 600 mOsm hyperosmotic environment induced the activation of proapoptotic members of the mitogen-activated protein kinase family such as c-Jun N-terminal kinase (JNK) and p38, and led to an increased level of extracellular signal regulated kinase (ERK1/2). Hyperosmotic stress also induced the activation of caspase-3. In summary, our results show that hyperosmotic stress leads to mainly apoptotic cell death via the involvement of proapoptotic signaling pathways in a primary chondrocyte culture.

Effects of pituitary adenylate cyclase activating polypeptide (PACAP) on the PKA-Bad-14-3-3 signaling pathway in glutamate-induced retinal injury in neonatal rats.

The neuropeptide PACAP (pituitary adenylate cyclase activating polypeptide) and its receptors are widely expressed in the nervous system including the retina. PACAP has well-known neuroprotective effects in neuronal cultures in vitro and against different insults in vivo. Recently, we have shown that PACAP1-38 is neuroprotective against monosodium glutamate (MSG)-induced retinal degeneration. Studying the molecular mechanisms of this protection has revealed that PACAP1-38 stimulates anti-apoptotic mechanisms such as phosphorylation of ERK1/2 and inhibits pro-apoptotic signaling molecules such as JNK1/2, p38MAPK, caspase-3 and the translocation of mitochondrial cytochrome c and apoptosis inducing factor in glutamate-treated retinas in vivo. In the present study we investigated the effects of PACAP1-38 on a further signal transduction pathway possibly involved in the protective effect of intravitreal PACAP1-38 administration against apoptotic retinal degeneration induced by neonatal MSG treatment. The focus of the present study was the protein kinase A (PKA)-Bad-14-3-3 transduction pathway. In vivo MSG treatment led to a reduction in the levels of anti-apoptotic molecules (phospho-PKA phospho-Bad, Bcl-xL and 14-3-3 proteins) in the retina. Co-treatment with PACAP1-38 counteracted these effects: the level of phospho-PKA, phospho-Bad, Bcl-xL and 14-3-3 were increased. All effects of PACAP1-38 were inhibited by the PACAP antagonist PACAP6-38. In summary, our results show that PACAP1-38 activates the PKA-Bad-14-3-3 pathway which is inhibited by MSG treatment. Our results also provide new insights into the signaling mechanisms possibly involved in the PACAP-mediated anti-apoptotic effects.

Comparative anatomy of PACAP-immunoreactive structures in the ventral nerve cord ganglia of lumbricid oligochaetes.

By means of a whole mount immunocytochemical approach, the distribution patterns of pituitary adenylate cyclase-activating polypeptide (PACAP)-27 and PACAP-38 were identified in the ventral nerve cord (VNC) ganglia of the earthworms Eisenia fetida and Lumbricus terrestris. Each PACAP form appears to occur in a distinct neuron population. Positions of these populations, as well as numbers and sizes of the constituting neurons do not essentially differ between the two species. The data suggest that in Lumbricid Oligochaetes, PACAP-27 and PACAP-38 neuron populations may mediate distinct physiological processes.

Presence of PACAP and VIP in embryonic chicken brain.

The aim of the present article was to investigate the occurrence and temporary changes of pituitary adenylate cyclase-activating polypeptide (PACAP)-38 and vasoactive intestinal peptide (VIP) in various brain areas of chicken embryos by means of radioimmunoassay. The highest concentrations of PACAP-38 were measured in the brain stem followed by the hypothalamus, cerebellum, and telencephalon. PACAP-38 levels were significantly higher than those of VIP in all examined brain areas. The levels of both PACAP-38 and VIP showed a tendency to decrease until hatching during embryonic development of the chicken.

Short-term fasting differentially alters PACAP and VIP levels in the brains of rat and chicken.

The present article investigated the levels of pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) in the brains of rats and chickens 12, 36, and 84 h after starvation. PACAP levels increased in both species, 12 h after food deprivation in rats, and with a 24-h delay in chickens. VIP levels showed a more complex pattern: a gradual increase in the hypothalamus and telencephalon, and a significant decrease in the brain stem of rats. In chickens, a decrease was observed in every brain area after 36 h of starvation. These data show that PACAP and VIP are differentially regulated and are involved in the regulatory processes under a food-restricted regimen, and are differentially altered in nocturnal and diurnal species.

Changes in PACAP levels in the central nervous system after ovariectomy and castration.

The aim of the present article was to investigate the influence of gonadectomy on pituitary adenylate cyclase-activating polypeptide (PACAP) levels in different brain areas. In males, there seems to be an inverse relationship between gonadotropins and PACAP in the brain in the acute phase of castration: PACAP levels decreased in almost all brain areas examined within the first week after castration. In females, such pattern was observed in the hypothalamus, brain stem, and temporal cortex. In the pituitary, levels decreased only on the first day after ovariectomy, and later, as in the thalamus, increases were observed. Although the pattern of change showed gender differences, our results provide further evidence that levels of gonadotropins and possibly gonadotropin-releasing hormone influence PACAP levels and that PACAP is involved in the regulation of gonadal functions.

The neuroprotective effects of PACAP in monosodium glutamate-induced retinal lesion involve inhibition of proapoptotic signaling pathways.

Pituitary adenylate cyclase activating polypeptide (PACAP) and its receptors are present in the retina and exert several distinct functions. PACAP has well-known neuroprotective effects in neuronal cultures in vitro and against different insults in vivo. Recently we have shown that PACAP is neuroprotective against monosodium glutamate (MSG)-induced retinal degeneration. In the present study we investigated the possible signal transduction pathways involved in the protective effect of intravitreal PACAP administration against apoptotic retinal degeneration induced by neonatal MSG treatment. MSG induced activation of proapoptotic signaling proteins and reduced the levels of antiapoptotic molecules in neonatal retinas. Co-treatment with PACAP attenuated the MSG-induced activation of caspase-3 and JNK, inhibited the MSG-induced cytosolic translocation of apoptosis inducing factor (AIF) and cytochrome c, and increased the level of phospho-Bad. Furthermore, PACAP treatment alone decreased cytosolic AIF and cytochrome c levels, while PACAP6-38 increased cytochrome c release, caspase-3 and JNK activity and decreased phospho-Bad activity. In summary, our results show that PACAP treatment attenuated the MSG-induced changes in apoptotic signaling molecules in vivo and suggest that also endogenously present PACAP has neuroprotective effects. These results may have further clinical implications in reducing glutamate-induced excitotoxicity in several ophthalmic diseases.

Age and gender differences in behavioral and morphological outcome after 6-hydroxydopamine-induced lesion of the substantia nigra in rats.

It is well known that Parkinson's disease occurs more commonly in older people and men are more frequently affected than women. Animal studies in models of the disease mainly use young male animals. The effects of aging on the neurochemical changes in the dopaminergic system have been extensively studied, however, data on comparative behavioral consequences of lesions of the dopaminergic system in aging and in female animals are limited. The aim of the present study was to give a detailed comparative behavioral analysis of young and aging male and female rats following 6-hydroxydopamine (6-OHDA) lesion of the substantia nigra. Young males and females, as well as aging males and females underwent 6-OHDA-induced lesion of the substantia nigra. Behavioral analysis in an open-field was performed before the injury, and 1 and 10 days after the operation. Tyrosine-hydroxylase (TH) immunohistochemistry was done in order to assess the dopaminergic cell loss in the substantia nigra. It was found that both young and aging male animals were more susceptible to 6-OHDA than females: female rats had a significantly less dopaminergic cell loss and responded to 6-OHDA with a significantly higher degree of behavioral recovery after the injury. Although the dopaminergic cell loss was not significantly different between young and aging animals of the same sex, aging rats showed more severe behavioral deficits. In summary, our present results showed clear age- and gender differences in the behavioral and histological outcome following 6-OHDA lesion of the substantia nigra.

Neurological reflexes and early motor behavior in rats subjected to neonatal hypoxic-ischemic injury.

Severe perinatal hypoxia-ischemia is an important cause of brain injury in both full-term and premature newborns, with a high risk of future behavioral and neurological deficits. The most commonly used animal model of neonatal hypoxia-ischemia is the unilateral ligation of the common carotid artery followed by exposure to hypoxia in 7-day-old rats. In spite of the wide use of this model, lot of contradictions and discrepancies exist between the results obtained by different laboratories regarding behavioral deficits and there are no data regarding the possible delay of the appearance of neurological reflexes and the time-course of reflex performances following neonatal hypoxic-ischemic injury in rats. In the present study we showed that neonatal hypoxia-ischemia retarded the development of somatic growth and several neurological reflexes (ear twitch, grasping, gait and negative geotaxis). Hypoxic animals also displayed retarded performance in righting, geotaxis and gait reflexes. Although hypoxic pups performed worse in most tests for motor coordination, they reached normal levels by 5 weeks of age except in the footfault test. In the open-field, hypoxic animals were generally more active, except at 3 weeks, when activity of normal pups increased enormously as well. Brain areas were significantly reduced in hypoxic animals, but no close correlation was found with behavioral deficits.

Comparative distribution of urocortin- and CRF-like immunoreactivities in the nervous system of the earthworm Lumbricus terrestris.

Corticotropin-releasing factor (CRF) and urocortin (Ucn) are both members of the CRF neuropeptide family. The distribution of Ucn- and CRF-like immunoreactive (ir) structures in the central nervous system of several vertebrate species has been studied, but little is known about that in non-vertebrates. We used a highly specific polyclonal antibody against rat Ucn and CRF to determine and compare the distribution of Ucn- and CRF-like immunoreactivity in the earthworm nervous system. Several Ucn- and CRF-like ir perikarya were described in the cerebral ganglion, subesophageal and ventral cord ganglia. The majority of Ucn-like ir cells were found in the ventral ganglia, whereas CRF-like ir cells were most abundant in the cerebral ganglion. Scattered Ucn- and CRF-like ir varicose fiber terminals were seen in all areas of the earthworm central nervous system. Ucn-like ir cell bodies and fiber terminals were also demonstrated in the pharyngeal wall. No co-localization of Ucn- and CRF-like ir nervous structures were observed. This study provided morphological evidence that Ucn- and CRF-like neurosecretory products exist in the earthworm central nervous system. Furthermore, both the distribution and morphology of Ucn- and CRF-like ir structures were distinct, therefore, it can be hypothesized that these neuropeptides exert different neurendocrine functions in the earthworm nervous system.

Morphological and functional effects of PACAP in 6-hydroxydopamine-induced lesion of the substantia nigra in rats.

Pituitary adenylate cyclase activating polypeptide (PACAP) has several different actions in the nervous system, including neuroprotective effects. In the present study, we investigated the effects of different doses of PACAP on the functional and morphological outcome in a rat model of Parkinson's disease. Rats were given unilateral injections of 6-hydroxydopamine (6-OHDA) into the substantia nigra. PACAP-treated animals received 1, 0.1 or 0.01 microg PACAP as a pretreatment. Control animals without PACAP treatment displayed severe hypokinesia at 1 and 10 days post-lesion when compared to normal animals or those receiving saline only. PACAP treatment resulted in less severe acute hypokinesia, and complete recovery by 10 days. Asymmetrical signs were observed in all lesioned animals 1 day post-lesion. PACAP-treated animals, however, showed better recovery as they ceased to display asymmetrical signs 10 days later and showed markedly less apomorphine-induced rotations. Best behavioral outcome was observed in animals treated with 0.1 microg PACAP. Tyrosine-hydroxylase (TH) immunohistochemistry revealed increased number of dopaminergic neurons in the substantia nigra pars compacta and in the ventral tegmental area in all PACAP-treated rats in contrast to the severe cell loss in control animals. These results indicate that PACAP may be a promising therapeutic agent in Parkinson's disease.

Effects of PACAP on in vitro and in vivo neuronal cell death, platelet aggregation, and production of reactive oxygen radicals.

Pituitary adenylate cyclase activating polypeptide (PACAP) exerts neuroprotective effects in various in vitro and in vivo models of cerebral pathologies. It has been shown that PACAP protects neurons in rat models of both global and focal ischemia. In the present study, we investigated factors that may play a role in the neuroprotective effects of PACAP. PACAP strongly reduced the anisomycin-induced apoptosis of PC12 cells, which was abolished in a PKA-deficient PC12 cell line (A126). This effect was also observed in vivo, in permanent occlusion of the middle cerebral artery, where the number of TUNEL-positive neurons was significantly reduced in the ischemic core of PACAP-treated animals. Our results show that PACAP has a minor antioxidant effect in a non-cellular in vitro system, and has considerable antioxidant effects in an in vitro red blood cell filtration model. PACAP had no effect on platelet aggregation induced by collagen, ADP or epinephrine. Our results demonstrate that the effects of PACAP on delayed neuronal death may play a significant role in the reduction of the infarct size in vivo, but the antioxidant effect could only be observed at concentrations higher than that used in the model of focal ischemia.

Comparative distribution of VIP in the central nervous system of various species measured by a new radioimmunoassay.

Vasoactive intestinal polypeptide (VIP) occurs in high concentrations throughout the gut and the nervous system. The presence of VIP has been shown in a number of species, mainly by immunohistochemistry. The aim of the present study was to develop a new, highly specific VIP radioimmunoassay to investigate the distribution of VIP in the central nervous system of various vertebrate and invertebrate species. Different areas of the brain and spinal cord were removed from rats, chickens, turtles, frogs and fishes. The cerebral ganglia and the ventral ganglionic chain were investigated in the earthworm. The tissue samples were processed for VIP radioimmunoassay. Our results show that the antiserum used in the radioimmunoassay turned to be C-terminal specific, without significant affinity to other members of the VIP peptide family. Detection limit of the assay was 0.1 fmol/ml. Highest concentrations were found in the turtle diencephalon, followed by other brain areas in the turtle and rat. All other brain areas in the examined species contained significant levels of VIP. Immunoreactivity was also shown in the cerebral and ventral ganglia of the earthworm. In summary, our results show comparative quantitative distribution in representative species of the phylogenetic line, using the same experimental conditions.