SEARCH · PubMed Health

Results for “Opossums”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources

PubMed2004

Prevalence of Sarcocystis species sporocysts in Northern Virginia opossums (Didelphis virginiana).

A total of 206 Virginia opossums ( Didelphis virginiana) collected from the mid-Michigan region, United States, during a period extending from 1996 to 2002 were sampled for the presence of Sarcocystis spp sporocysts. All isolates were phenotypically identified as Sarcocystis spp and genotyped to the species level by PCR-based techniques. The overall prevalence of Sarcocystis spp in opossums was 18% (37/206). The prevalence of Sarcocystis spp differed significantly with age ( P<0.001) and adult opossums were more commonly infected (14.6%; 30/206) than juveniles (3.4%; 7/206). No significant difference in the prevalence of Sarcocystis spp infection was observed between male and female ( P<0.15). The highest prevalence was recorded during summer (9.2%; 19/206). PCR-RFLP analyses demonstrated the majority of Sarcocystis isolates to be S. neurona, with some animals co-infected with sporocysts of S. falcatula. Out of the 37 Sarcocystis-infected opossums, 23 (62%) had sporocysts of S. neurona only, four (11%) had sporocysts of S. falcatula only, and eight (22%) had a mixture of S. neurona and S. falcatula sporocysts. These findings indicate that mixed Sarcocystis infections in opossums are common. The propensity for Sarcocystis spp to co-exist in the opossum gut enhances dissemination and environmental contamination with these coccidia. Additionally, this increases the chance for sexual recombination between Sarcocystis spp, given the proclivity of these species to reproduce sexually at high numbers in the intestinal cells of their definitive host.

Animals↗

PubMed1991

Production of interleukin-1 in a South American opossum (Monodelphis domestica).

A homologous thymocyte costimulatory assay using thymocytes from a South American opossum (Monodelphis domestica) detected and measured interleukin-1 (IL-1). Opossum IL-1 was obtained from lipopolysaccharide-stimulated macrophage and skin cultures and its molecular weight was determined to be 15,000 to 17,000. Opossum IL-1 did not stimulate proliferation of murine thymocytes; conversely, neither human nor murine IL-1 stimulated opossum thymocytes. Anti-human IL-1 antibodies were also not reactive with opossum IL-1. These observations indicate that there is no serological and functional crossreactivity between the opossum (marsupial mammals) and human and mouse (eutherian mammals) in an IL-1/thymocyte system. This is unusual because such crossreactivity occurs between rodents and distant, nonmammalian species. M. domestica has been used in our laboratory as a model for photobiological research; studies on IL-1 may provide insight into the relationship of immunosuppression and tumorigenesis induced by ultraviolet radiation.

Animals↗

PubMed1991

Ontogeny of cells containing estrogen receptor-like immunoreactivity in the Brazilian opossum brain.

In this study, we have used the Brazilian short-tailed opossum (Monodelphis domestica) as a model to study the ontogeny of estrogen receptors in the mammalian brain. Monodelphis is a small, pouchless marsupial which breeds well under laboratory conditions and whose young are born in an immature sexually undifferentiated state. The Abbott H222 monoclonal rat estrogen receptor antibody (gift of Abbott Laboratories) was utilized in an indirect immunohistochemical procedure to detect estrogen receptors in developing opossum brains. Estrogen receptors were first expressed in the dorsomedial and ventromedial hypothalamus of the opossum 10 days after birth (10PN). Most regions that contained estrogen receptor-like immunoreactivity (ER LI) in the adult opossum contained ER LI at 15 PN. These areas include the lateral septum, medial preoptic area, bed nucleus of the stria terminalis, periventricular preoptic area and hypothalamus, amygdala, dorsomedial and ventromedial hypothalamic nuclei, arcuate nucleus, ventral premammillary nucleus, and the midbrain central grey. The number of cells that contain ER LI increased through 60PN in all regions that will contain ER LI in the adult opossum. These results indicate that estrogen receptors are present in early development of the Monodelphis brain and may mark the beginning of a critical period for sexual differentiation of the opossum brain.

Animals↗

PubMed2004

Cholesterol absorption and hepatic acyl-coenzyme A:cholesterol acyltransferase activity play major roles in lipemic response to dietary cholesterol and fat in laboratory opossums.

Partially inbred lines of laboratory opossums differ considerably in their low-density lipoprotein (LDL) cholesterol responses to dietary cholesterol and fat. Genetic analysis suggested that a single major gene is responsible for the variation in LDL cholesterol on the high cholesterol and high fat (HCHF) diet. We measured cholesterol absorption and acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity in intestine and liver to narrow the search for the major gene. We measured plasma lipoproteins and percent cholesterol absorption by the fecal isotope ratio method in high and low responding lines of opossums on basal and HCHF diets. We also measured lipids in liver and ACAT activity in liver and intestine on the HCHF diet. High and low lines exhibited no differences in percent cholesterol absorption on the basal diet. However, high responding opossums had significantly higher percent cholesterol absorption, hepatic free and esterified cholesterol, and hepatic ACAT activity than low responding opossums on the HCHF diet. Hepatic ACAT activity but not the intestinal ACAT activity was associated with hepatic cholesterol concentration and percent cholesterol absorption. Cholesterol absorption is a major determinant of diet-induced hyperlipidemia in opossums. Hepatic ACAT activity but not the intestinal ACAT may also play a role in diet-induced hyperlipidemia in opossums.

Animal Feed↗

PubMed2004

Prevalence of and risk factors associated with the presence of Sarcocystis neurona sporocysts in opossum (Didelphis virginiana) from Michigan: a retrospective study.

From April 1996 to December 2002 the prevalence of Sarcocystis neurona sporocysts in North American opossum (Didelphis virginiana) in Southern Michigan was estimated. Sporocysts of S. neurona were found in intestinal scrapings from 31 (15%) of 206 examined opossum. The frequency of infection was higher in adult animals (26/206; 12.6%) and females (19/206; 9.2%) than in juveniles (5/206; 2.4%) and males (12/206; 5.8%). Also, prevalence of S. neurona sporocysts in opossums in relation to factors such as age, sex, season, body condition, presence of concomitant infection, and presence of young in the pouch of females was studied in detail over the course of the year, 2002. Univariate analyses identified the following factors as being associated with the presence of S. neurona sporocysts in opossums: (i) for age, adult (odd ratio [OR] = 2.074, P = 0.0005); (ii) for sex, female (OR = 7.016, P = 0.0119); (iii) for season, summer (OR = 7.917, P = 0.0032) and spring (OR = 4.071, P = 0.1063); (iv) for body condition, poor (OR = 3.50, P = 0.1200) and good (OR = 1.167, P = 0.8637); (v) for the presence of concomitant infection (OR = 23.056, P = 0001), and (vi) for the presence of young in the pouch of females (OR = 40.083, P = 0.0001). Multivariate logistic-regression analyses selected the following factors as being significantly associated with presence of S. neurona sporocysts in opossums: (i) for the presence of concomitant infection (OR = 8.722, P = 0.0160) and (ii) for the presence of young in the pouch of females (OR = 31.915, P = 0.0065). The prevalence of S. neurona sporocysts in D. virginiana suggests that this opossum may constitute an ample reservoir of infection to other animals in the northern United States.

Age Factors↗

PubMed2002

The effects of Western Diamondback Rattlesnake (Crotalus atrox) venom on the production of antihemorrhagins and/or antibodies in the Virginia opossum (Didelphis virginiana).

Opossums are animals that are naturally resistant to the proteolytic effects of Crotalid venoms. Opossums possess proteinase inhibitors in their sera that bind to and neutralize hemorrhagic and other proteolytic activity in many snake venoms. The proteinase inhibitors are not antibodies since they have different molecular weights (60kDa) and pI (4.2). The purpose of this study was to determine if opossums were capable of producing antibodies against venom and/or increasing the production of proteinase inhibitors (specifically antihemorrhagins). Five different venom immunization protocols were used to determine the effects of the venom in the opossums. The dosages ranged from 1mg of venom per immunization to 350mg/kg body weight of venom per immunization. The antihemorrhagic response was increased, but there is no evidence to suggest that an opossum can produce antibodies against venom. The lack of an antibody response is most likely due to the natural proteinase inhibitors clearing the venom from the opossum's body before an antibody response can occur.

Animals↗

PubMed2001

Prevalence of Sarcocystis neurona sporocysts in opossums (Didelphis virginiana) from rural Mississippi.

Sarcocystis species sporocysts were found in intestinal scrapings from 24 of 72 opossums (Didelphis virginiana) from rural Mississippi. The number of sporocysts in each opossum varied from a few ( < 100000) to 187 million. Sporocysts from 24 opossums were bioassayed for Sarcocystis neurona infections by feeding to gamma-interferon knockout (KO) mice. S. neurona was detected in the brains of KO mice fed sporocysts from 19 opossums by immunohistochemical staining with anti-S. neurona specific polyclonal rabbit serum, and by in vitro culture from the brains of KO mice fed sporocysts. The isolates of S. neurona from opossums were designated SN16-OP to SN34-OP. Merozoites from 17 of 19 isolates tested at the 25/396 locus were identical to previously described S. neurona isolates from horses. The high prevalence of S. neurona sparocysts in D. virginiana suggests that this opossum constitutes an ample reservoir of infection in the southern United States.

Animals↗

PubMed2000

Control of respiration in the isolated central nervous system of the neonatal opossum, Monodelphis domestica.

Respiration represents an unusual motor activity with respect to its development. As newly born mammals enter the world, their limb movements are not coordinated; time and experience are required for effective performance to be achieved. Yet the rhythm of respiration is of necessity functionally perfected and unfailing at birth. Inspiratory and expiratory motor neurons are already able to fire at appropriate rates, under the command of rhythmically active neurons in the medulla. In this review, we discuss refinements of control present in the newborn opossum, particularly with respect to mechanisms that allow adaptation of respiration to changes in the level of activity or in the outside environment. Our own studies have been aimed at analyzing respiration at the earliest stages, and at establishing the way in which important variables influence inspiration and expiration. To this end, we have used the central nervous system (CNS) of a neonatal opossum, isolated in its entirety and maintained in culture. Although the opossum is unable to walk and highly immature at birth, its respiration is regular and unfailing. The isolated CNS survives, undergoes development, and maintains its neural activity and fine structure in vitro. Moreover, fictive respiration persists for over a day or longer at rates similar to those of the intact pup. The effects of altered pH, of increased temperature, and of drugs known to alter respiratory rhythm in intact animals can be measured directly, by electrical recordings made from medullary neurons or ventral roots. As in a slice, fluids of different composition can be applied focally, through micropipettes to the surface of the ventral medulla, or diffusely to the brainstem, With highly localized application of procaine hydrochloride (2%) to selected areas of the ventral medulla, the respiratory rhythm is reduced or abolished. As in adult mammals, both the rate and the amplitude of respiration simultaneously increase in response to lowered pH (6.5-.7.1) or to topical application of 1.0 microM carbachol. Conversely, as expected, the rate and amplitude decrease in response to increased pH (pH 7.5-7.7), or 100 microM scopolamine. Two characteristic features of the control of respiration in the neonatal opossum are evident from such tests. First, changes in rate are achieved by changes in the duration of the expiratory phase of respiration. This result suggests that the timing of the respiratory cycle in the neonatal opossum is controlled by an expiratory instead of an inspiratory "off-switch". Second, the rate and the amplitude of the respiratory excursions can be controlled independently, depending on the stimulus. For example, an increase in temperature increases the rate of fictive respiration without changing its amplitude, whereas noradrenaline decreases the rate while increasing the amplitude. Thus, changes of timing and amplitude need not go hand in hand. The opossum CNS offers a favorable preparation for the analysis of neural mechanisms that generate and modulate a motor rhythm, as the animal develops from embryonic to adult stages.

Animals↗

PubMedDate not supplied

Humoral immune response kinetics in Philander opossum and Didelphis marsupialis infected and immunized by Trypanosoma cruzi employing an immunofluorescence antibody test.

Philander opossum and Didelphis marsupialis considered the most ancient mammals and an evolutionary success, maintain parasitism by Trypanosoma cruzi without developing any apparent disease or important tissue lesion. In order to elucidate this well-balanced interaction, we decided to compare the humoral immune response kinetics of the two didelphids naturally and experimentally infected with T. cruzi and immunized by different schedules of parasite antigens, employing an indirect fluorescence antibody test (IFAT). Both didelphids responded with high serological titers to different immunization routes, while the earliest response occurred with the intradermic route. Serological titers of naturally infected P. opossum showed a significant individual variation, while those of D. marsupialis remained stable during the entire follow-up period. The serological titers of the experimentally infected animals varied according to the inoculated strain. Our data suggest that (1) IFAT was sensitive for follow-up of P. opossum in natural and experimental T. cruzi infections; (2) both P. opossum and D. marsupialis are able to mount an efficient humoral immune response as compared to placental mammals; (3) experimentally infected P. opossum and D. marsupialis present distinct patterns of infection, depending on the subpopulation of T. cruzi, (4) the differences observed in the humoral immune responses between P. opossum and D. marsupialis, probably, reflect distinct strategies selected by these animals during their coevolution with T. cruzi.

Animals↗

PubMed2002

A retrospective study of 11 cases of lungworm (Didelphostrongylus hayesi) infection in opossums (Didelphis virginiana).

A juvenile, female North American opossum (Didelphis virginiana) died of verminous pneumonia caused by Didelphostrongylus haysei despite aggressive treatment with oral fenbendazole, corticosteroids, and antibiotics. This prompted a retrospective study of lungworm infection in opossums, during which 19 additional necropsy reports from opossums were reviewed. Including the subject of this report, a total of 11 (55%) of these cases included a diagnosis of lungworm infection. This diagnosis was considered to have contributed to death in eight out of the 11 cases (73%). Histologically, 10 of the 11 (91%) opossums had granulomatous bronchopneumonia with small to moderate numbers of adult nematodes in the airways and parenchyma. Four of the 11 (36%) opossums had free larvae within the parenchyma or terminal airways. Inflammation was usually associated with larvae, degenerating parasites, and nonintact adult nematodes. Superimposed bacterial pneumonia was evident in three animals, and sections of lung examined from all the opossums were characterized by moderate to severe smooth-muscle hyperplasia in airways, including terminal respiratory bronchioles and alveolar ducts. Nine animals had prominent medial smooth-muscle hyperplasia in small- and medium-sized arterioles. Lesions in other organs, particularly in liver, heart, and gastrointestinal tract, were frequently identified. Three animals had concomitant septicemia or bacterial bronchopneumonia (or both), which contributed to the cause of death. Seven animals had gastric nematodosis (Physaloptera sp.), although three of them had been treated with a 14-day course of fenbendazole.

Animals↗

PubMed1994

Immunocytochemical localization of vacuolar H-ATPase in the opossum (Monodelphis domestica) kidney: comparison with the rat.

With two different antibodies (a monoclonal antibody to the C terminus of the 31-kd subunit of H-ATPase and a polyclonal rabbit antiserum to whole bovine H-ATPase) the vacuolar-type H-ATPase pump in the different nephron segments of the gray short-tailed (Monodelphis domestica) opossum kidney has been immunocytochemically localized. There was moderate staining of the brush border and subvillar invaginations in the proximal convoluted tubules (PCT) of the opossum kidney only with the rabbit antiserum and not with the monoclonal antibody. This was in contrast to the rat kidney, where both antibodies showed significant staining of the brush border and subvillar invaginations. There was very minimal staining in the apical region of the thick ascending limb cells of the opossum as compared with a mild degree present in the rat kidney. The pattern and intensity of staining were similar in the remaining distal nephron segments with the only difference being that type A intercalated cells in the outer and inner medullary collecting ducts were less polarized in the opossum kidney. These findings suggest that different isoforms of H-ATPase exist in the brush border of the PCT versus the intercalated cells of the collecting duct in the opossum and between the PCT of opossum and rat kidneys.

Animals↗

PubMed1999

Simplified technique for isolation, excystation, and culture of Sarcocystis species from opossums.

Sarcocystis neurona is a protozoan parasite that causes a neurological disease in horses called equine protozoal myeloencephalitis. The route of transmission is speculated to be by fecal-oral transfer of sporocysts shed from opossums. Controversy exists regarding both the natural life cycle for this parasite as well as the species identity of opossum Sarcocystis. To provide stage-specific material for species comparison, 27 opossums from southern Michigan were screened for Sarcocystis spp. sporocysts. Seven opossums were positive for Sarcocystis sporocysts by fecal flotation. A simplified, effective technique for isolation, excystation, and culture of opossum Sarcocystis sp. from mucosal scrapings was developed. All 7 Sarcocystis sp. isolates were successfully cultured to grow long term in equine dermal cells to the merozoite stage. Merozoites were observed between 5 and 15 days after inoculation. In conclusion, opossums shed Sarcocystis sp. sporocysts that may be manipulated to excyst and grow in vitro in equine dermal cell lines to the merozoite stage using the simplified technique described.

Animals↗

PubMed1991

Salmonella infection of the biliary and intestinal tract of wild opossums.

Bacteriologic cultures were taken from the mesenteric lymph nodes, biliary tract, blood, liver, spleen and pancreas of opossums (Didelphis virginiana) obtained directly from the wild for use as research animals. The overall incidence of salmonellosis outside the intestinal tract was 61% among 18 opossums. Salmonella was recovered from the gallbladder of six (33%) animals, indicating chronic biliary tract infection. Among these six animals, translocation of Salmonella to regional lymph nodes was observed in five animals, bacteremia in three animals, and spread to liver or spleen in five animals, respectively. The biliary tract was sterile in 12 opossums (67%). In these 12 animals, bacteria were isolated from the celiac and superior mesenteric lymph nodes of five animals, the blood of two animals, and the liver and spleen of one animal, respectively. Bacteriologic cultures were obtained from the intestinal tract and from extraintestinal sites in nine opossums. Salmonella were found in the small bowel of two animals, both of which had biliary salmonellosis. In addition, Salmonella was isolated from extraintestinal organs of three animals with negative cultures from the gut. All isolates identified were: S. enterica subsp houtenae. These data establish the biliary tract of wild opossums as a reservoir for Salmonella enterica subsp houtenae which may be particularly important when opossums are used in research laboratories.

Animals↗

PubMed1982

Functional studies on hemoglobin opossum. Conclusions drawn regarding the role of the distal histidine.

In the hemoglobin of the opossum, the alpha chains have different residues at positions E7 and E11 than do most other mammalian hemoglobins. In the opossum, the usual histidine at alpha E7 is replaced by glutamine, the valine at alpha E11 by isoleucine, and the hemoglobin is known to have a low oxygen affinity and a low Hill coefficient. Comparison of kinetic studies of opossum hemoglobin with normal human hemoglobin shows that alpha chains in Hb opossum, despite the lack of distal histidine, do not differ significantly in CO-combination rates in either the T or R states. These rates are much slower than the rates reported for Hb Zurich, the hemoglobin from Chironomus thumi thumi, or the monomeric components of glycera hemoglobin, all of which also have a different residue at E7. As compared with Hb A, the changes in ligand affinities in the T and R states are small and cannot account for the unusually high values of p50 for Hb opossum. The equilibrium and kinetic data indicate that the L = (T)/(R) is about 100 times higher for Hb opossum than for Hb A; CCO = KR/KT approximately equal to 0.014. The kinetic data on l'4 and l also indicate that the R leads to T equilibrium for Hb4(CO)4 and Hb4(CO)2 can be shifted in either direction by adding inositol hexaphosphate or by changing the pH.

Animals↗

PubMed1994

[Prospects for obtaining a mapping panel for somatic cell marsupial-rodent hybrids for the short-tailed opossum Monodelphis domestica].

A possibility of obtaining a panel of marsupial-rodent somatic cell hybrid clones has been explored, with a view to mapping the genome of the opossum (Monodelphis domestica). Fusion of opossum cells (splenocytes, bone marrow cells, and fibroblasts) with fibroblasts of Chinese hamster or vole (HGPRT- and TK- mutants, respectively) produced 146 hybrid clones. The majority of marsupial-mammalian somatic cell hybrids were characterized by pronounced fragmentation and segregation of marsupial chromosomes. To overcome this difficulty, a method for rapid screening was developed, which allowed the early selection of clones rich in chromosomal material of opossum. Based on the screening results, 25 clones of independent origin were selected. A detailed genetic analysis, which included chromosome G-banding and in situ hybridization of biotin-labeled opossum DNA on metaphase chromosomes, allowed further selection of seven hybrid clones containing one to six intact chromosomes of M. domestica. Opossum chromosomes were present in various combinations against the background of Chinese hamster or vole chromosomes. The clones will be included in the panel of opossum-rodent somatic cell hybrids, which is currently being created.

Animals↗

PubMed1998

Marsupial light chains: complexity and conservation of lambda in the opossum Monodelphis domestica.

The Ig lambda chains in the South American opossum, Monodelphis domestica, were analyzed at the expressed cDNA and genomic organization level, the first described for a nonplacental mammal. The V lambda segment repertoire in the opossum was found to be comprised of at least three diverse V lambda families. Each of these families appears to be related to distinct V lambda families present in placental mammals, suggesting the divergence of these genes before the separation of metatherians and eutherians more than 100 million years ago. Based on framework and constant region sequences from full-length cDNAs and intron sequences from genomic clones, it appears that there are multiple functional J lambda-C lambda pairs in the opossum locus. The opossum J lambda-C lambda sequences are phylogenetically clustered, suggesting that these gene duplications are more recent and species specific. Sequence analysis of a large set of functional, expressed V lambda-J lambda recombinations is consistent with an unbiased, highly diverse lambda light chain repertoire in the adult opossum. Overall, the complexity of the Ig lambda locus appears to be greater than that found in the Ig heavy chain locus in the opossum, and light chains are therefore likely to contribute significantly to Ig diversity in this species.

Amino Acid Sequence↗

PubMed1989

Prostaglandin F in reproductive tissues collected during the luteal phase of the estrous cycle and at parturition in Virginia opossums (Didelphis virginiana ).

Prostaglandin F(2alpha) (PGF(2alpha)) plays a role in the regression of the corpus luteum (CL) in a number of placental mammals. However, the mechanism of luteal regression has not been extensively studied in marsupials. The objectives of this study were to characterize changes in concentrations of PGF(2alpha) within utero-ovarian (UO) tissue/venous plasma during the luteal phase of the estrous cycle in Virginia opossums, to correlate these changes with those of plasma progesterone (P(4)), and to characterize the peripheral pattern of 13,14-dihydro-15-keto-PGF(2alpha) (PGFM) in parturient opossums. Ovaries, uteri, UO venous plasma and peripheral plasma were collected on Days 5, 9 and 12 after induced ovulation (n = 3 to 4 opossums/group). In addition, concentrations of PGFM were measured in peripheral plasma collected from two opossums during late gestation (Days 7,9,11 and 12) and at parturition (Day 13). Concentrations of P(4), PGFM and PGF(2alpha) in tissue homogenates and plasma samples were estimated by radioimmunoassay. In nonpregnant opossums, peripheral P(4) levels were highest on Day 5 (38.8 +/- 11.1 ng/ml, x +/- SEM) declined on Day 9 (22.6 +/- 7.4 ng/ml), and were at basal levels by Day 12 (2.4 +/- 0.7 ng/ml). Endometrial concentrations of PGF(2alpha) increased (P = 0.056) from Day 5 (15.7 +/- 4.1 ng/g) to Day 9 (92.1 +/- 61.0 ng/g) and were maintained to Day 12 (97.2 +/- 25.7 ng/g). Prostaglandin F(2alpha) concentrations in UO plasma increased (P < 0.01) from Day 5 (143.1 +/- 32.7 pg/ml) to Day 12 (333.0 +/- 32.4 pg/ml). Prostaglandin F(2alpha) concentrations in ovarian tissue followed a similar pattern and were correlated with UO concentrations (r = 0.708, P < 0.05). In pregnant opossums, the highest levels of peripheral PGFM were recorded in the peripartum period, when luteal regression would also be expected to occur. The negative temporal relationship between peripheral concentrations of P(4) and concentrations of PGF(2alpha) in UO tissue/venous plasma observed in this preliminary study is consistent with the notion that PGF(2alpha) from the ovary and/or uterus may play a role in CL regression in the opossum.

Journal Article↗

PubMed1993

Localization of cholecystokinin binding sites in the adult and developing Brazilian opossum brain.

Cholecystokinin (CCK) is now recognized as one of the most abundant peptides in the mammalian central nervous system. We have previously used immunohistochemistry to localize CCK in the adult and developing Brazilian opossum brain. However, little is known about the distribution of CCK binding sites in the developing mammalian brain. Therefore, to further our knowledge of the sites of action for CCK during development, we initiated a series of studies to localize CCK binding sites in the adult and developing Brazilian opossum. This species was chosen because pups are born in a fetus-like state. Receptor autoradiography was performed on coronally sectioned brains of 1 to 60 day postnatal (PN) animals and adults with 125I-Bolton Hunter-CCK-8 as the radioligand. Binding is evident in the 1PN opossum brainstem and is observed in the developing forebrain by 5PN. Region-specific binding increases during development, and binding in the 35PN brain resembles the adult pattern. Binding is evident prior to the detection of CCK-like immunoreactivity in many areas. The facial motor nucleus is identifiable and exhibits high levels of binding in Brazilian opossum pups of 10 to 35 days of age. However, binding is undetectable in the facial motor nucleus of 45 and 60PN pups. In general, the binding patterns for CCK in the adult opossum resemble those of other mammals and likely mediate similar physiological functions. However, some cholecystokininergic pathways appear to be unique to neonatal mammals.

Animals↗