Inhibition of varicella-zoster virus glycoprotein expression by peripheral blood mononuclear cells

The effect of peripheral blood mononuclear cells (PBMC) on expression of varicella-zoster virus (VZV) glycoproteins (Gps) was analyzed by flow cytometry. PBMC from VZV seropositive and seronegative donors and supernatant of PBMC co-cultured with VZV-infected human embryonic fibroblasts reduced VZV Gp expression. Neutralization of supernatant fluid with mixture of anti-interferons (IFN)-alpha, -beta, -gamma, and tumor necrosis factor (TNF)-alpha partially reduced inhibitory activity of supernatant on VZV Gp expression. Deletion of natural killer (NK) cells and adherent cells from PBMC reduced inhibitory activity of PBMC on VZV Gp expression. These results suggest that IFN-alpha, -beta, -gamma, TNF-alpha and other soluble factors released from NK cells and monocytes by co-cultivation with VZV-infected fibroblasts inhibit VZV Gp expression.

Role of epidermal Langerhans' cells in the induction of protective immunity to Schistosoma mansoni in guinea-pigs

Percutaneous exposure of guinea-pigs to attenuated or normal larvae of Schistosoma mansoni induced proliferative T-cell responses in the skin-draining lymph nodes (SLN). The responses elicited by attenuated larvae were stronger and more prolonged [2-12 days post-infection (p.i.)] than those by normal larvae (3-8 days p.i.). The former were coincident with greater and more sustained increases in numbers of SLN dendritic cells. During this event, epidermal Langerhans' cells (LC) showed marked changes in their distribution and morphology. Resident LC were similarly exhausted by either attenuated or normal larvae between 12 hr and 1 day p.i., but thereafter more blood-borne LC were recruited around the former, since reaggregation of LC around these persisted larvae was more frequent and intensive, and enhanced replenishment of epidermal LC was achieved by 8 days p.i. When the skin depleted of epidermal LC by short-wavelength ultraviolet (UVC) irradiation was exposed to attenuated larvae, consequent T-cell responses were delayed. Excision of the whole exposed skin on day 4 p.i. also reduced T-cell responses to marginal levels. These results indicate that during the afferent phase of immunity to S. mansoni, efficient T-cell responses in the SLN need an active involvement of not only resident LC but also blood-borne LC as immunostimulatory cells.

Increased expression of adhesion molecules (CD54, CD29 and CD44) on fibroblasts infected with cytomegalovirus

The expression of ICAM-1 (CD54), beta 1 integrin (CD29), and CD44 on cytomegalovirus (CMV)-infected human embryonic fibroblasts (HEF) was analyzed by flow cytometry. The expression of these adhesion molecules increased significantly on CMV-infected HEF, on days 2 and 5 after inoculation, compared to uninfected HEF. However, the expression of these adhesion molecules decreased on herpes simplex virus (HSV)-1 and varicella-zoster virus (VZV)-infected HEF. Increased expression was not observed on HEF treated either with inactivated CMV or with supernatant fluid of CMV-infected cells. The addition of anti-cytokine (TNF-alpha, IL-1 beta, or IFN-gamma) antibodies had no effect on the increase of these adhesion molecules. This suggests that the increase in CD54, CD29, and CD44 on CMV-infected cells requires active virus replication and was not mediated by a soluble factor released from CMV-infected cells. Changes in adhesion molecules on CMV-infected fibroblasts may contribute to inflammation induced by CMV infection.

Fas antigen and bcl-2 expression on lymphocytes cultured with cytomegalovirus and varicella-zoster virus antigen

Fas antigen and bcl-2 expression on peripheral blood mononuclear cells (PBMC) cultured with cytomegalovirus (CMV) and varicella-zoster virus (VZV) antigen was analyzed by three-color flow cytometry. Expression of Fas antigen increased significantly in CD45RO+ populations of both CD4+ and CD8+ cells obtained from CMV and VZV seropositive donors after culture with CMV and VZV antigen for 6 days. Fas antigen expression did not increase in PBMC cultured with control antigen. In contrast, bcl-2 expression decreased both in CD4+CD45RO+ and CD8+CD45RO+ cells from the same donors. Fas antigen and bcl-2 expression in CD45RA+ populations did not change. Cell viability of cultured cells with CMV and VZV antigen decreased after treatment with anti-Fas antibody and DNA fragments indicating apoptosis were detected in the cell lysate of these cultured cells after treatment with anti-Fas antibody. These data suggest that Fas antigen and bcl-2 protein may interact in regulating the cell death process of activated memory lymphocytes and eliminating lymphocytes activated by viral infection.

2-Hydroxyadenine (isoguanine) as oxidative DNA damage: its formation and mutation inducibility

In our experiments we found that hydroxylation occurs at the C-2 position of adenine by oxygen radical treatment (Fe(2+)-EDTA) of dA, dATP, and single- and double-stranded DNA. This oxidatively damaged base, 2-hydroxyadenine (also known as isoguanine), was produced more efficiently in monomers than in polynucleotides. 2-Hydroxydeoxyadenosine triphosphate was incorporated opposite T and C in a DNA template by DNA polymerase alpha and only opposite T by the Klenow fragment. The Klenow fragment, DNA polymerases alpha and beta incorporated dTMP and other nucleotides opposite 2-OH-Ade in DNA templates in vitro in a sequence-dependent manner. These results suggest that the formation of 2-OH-Ade in DNA will induce mutations in cells.

Detection of human cytomegalovirus DNA in immunocompromised children by polymerase chain reaction

BACKGROUND

Cytomegalovirus (CMV) infection is a major complication in immunocompromised patients, such as those with leukemia, acquired immunodeficiency syndrome (AIDS) and allograft recipients. A sensitive and specific diagnostic procedure of CMV infection is required. The polymerase chain reaction (PCR) procedure has been demonstrated to be more sensitive than conventional virus isolation. However, CMV DNA can be detected in patients with latent or asymptomatic infections by PCR because of its extreme sensitivity.

OBJECTIVES

In this study, we used PCR and reverse transcription PCR (RT-PCR) to detect CMV DNA and mRNA in immunocompromised patients and evaluated the value of PCR and RT-PCR for diagnosis of active CMV infection.

STUDY DESIGN

We examined thirty immunocompromised children for CMV DNA using peripheral blood mononuclear cells (PBMC), polymorphonuclear leukocytes (PMNL). urine and throat swabs from October 1991 to March 1992. Eighteen of the patients had acute lymphoblastic leukemia, four had non-Hodgkin's lymphoma, two had Wilms' tumor and six were recipients of an allogeneic bone marrow transplantation. Four patients developed CMV-related clinical symptoms during the observation period: two patients with pneumonia and two patients with hepatitis.

RESULTS

CMV DNA was detected in four patients with clinical symptoms and in five patients without evidence of CMV infection. The incidence of CMV DNA was significantly higher in symptomatic patients than asymptomatic patients. CMV mRNA encoding the late antigen was detected by RT-PCR only in patients with clinical symptoms of CMV infection.

CONCLUSIONS

We concluded that detection of CMV DNA by PCR is of little clinical significance for distinguishing latent form active CMV infection. It is suggested that detection of CMV mRNA by RT-PCR is useful for diagnosis of active CMV infection.

Changes of adhesion molecule (LFA-1, ICAM-1) expression on memory T cells activated with cytomegalovirus antigen

The expression of adhesion molecules (LFA-1, ICAM-1, CD29) on T cells activated with cytomegalovirus (CMV) antigen was investigated by three-color flow cytometry analysis. Peripheral blood mononuclear cells (PBMC) from CMV-seropositive adults were cultured with CMV or control antigen for 6 days. After culture, the expression of LFA-1, ICAM-1, and CD29 on T cells in subpopulations defined as CD45RO+ or CD45RO- was analyzed. The population of cells that expressed LFA-1 at high levels (LFA-1high) among CD4+C-D45RO+ cells increased when cultured with CMV antigen compared to control antigen. The population of cells that expressed LFA-1high cells among CD8+C-D45RO+ cells was down-regulated by culture for 6 days; however, the population of LFA-1high cells among CD8+CD45RO+ cells cultured with CMV antigen was higher than when cultured with control antigen. The population of LFA-1high cells among CD4+CD45RO- and CD8+CD45RO- cells did not change after culture with CMV antigen. The intensity of CD29 and expression of ICAM-1 also increased on both CD4+CD45RO+ and CD8+CD45RO+ cells after culture with the CMV antigen. Up-regulation of adhesion molecules occurred on activated T cells by culture with the CMV antigen. This change was observed mainly on CD45RO+ T memory cells. The results suggested that these changes of adhesion molecules on activated T cells with CMV may contribute to some immune reaction or inflammatory change.

Changes in 3H-quinuclidinyl benzilate binding and protein synthesis in the striatum following chronic administrations of muscarinic agonist

Injection of the muscarinic agonist oxotremorine into rat striatum for seven consecutive days resulted in a 44% reduction in 3H-quinuclidinyl benzilate (3H-QNB) binding, and it caused decreases in binding affinity to agonists. Furthermore, it eliminated the shift from the high affinity site to the low affinity site that occurs in the presence of 5'-guanylyl imidodiphosphate (Gpp (NH)p). In addition, oxotremorine caused a 1.5-fold increase in the incorporation of 3H-leucine into the striatum, suggesting that it increased the syntheses of proteins other than the muscarinic receptor protein. The present results show that chronic treatment of the striatum with oxotremorine causes alterations in not only the quantity, but also the sensitivity of muscarinic receptors to guanine nucleotide.

Inhibitory effect of transforming growth factor beta 1 on cytokine-enhanced eosinophil survival and degranulation

The effects of transforming growth factor (TGF) beta 1 on cytokine-enhanced eosinophil survival and degranulation were investigated in vitro to determine whether it is an inhibitory regulator of allergic inflammation. Peripheral blood eosinophils purified by Percoll density gradient centrifugation and the CD16 negative selection technique were incubated in the presence of eosinophil-activating cytokines (interleukin-5 (IL-5), IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-gamma) with and without TFG-beta 1 for 1-3 days. On day 1, eosinophil protein X release was measured by radioimmunoassay. Eosinophil viability on day 3 was determined by staining the cells with fluorescein diacetate and propidium iodide, and on the same day DNA was extracted and subjected to gel electrophoresis to test for fragmentation. TGF-beta 1 significantly inhibited eosinophil survival enhanced by IL-5, IL-3, GM-CSF and IFN-gamma in a dose-dependent manner. The inhibitory effects of TGF-beta 1 on IL-5-enhanced survival was partially reversed by high concentrations of IL-5 and was completely neutralized with anti-TGF-beta antibody. IL-5 inhibited DNA fragmentation of eosinophils in vitro. TGF-beta reversed the effect of IL-5, indicating that TGF-beta 1 activates the pathway of apoptosis. TGF-beta 1 significantly suppressed eosinophil protein X release induced by IL-5. These results suggest that TGF-beta 1 may play a role in the modulation of allergic inflammation.

[Studies on SY5555 in the field of pediatrics]

SY5555, a new oral penem, in the form of dry syrup (powder which is dissolved before use) was evaluated for its pharmacokinetics and clinical efficacy in pediatric patients. Oral administration of 5 mg/kg and 10 mg/kg of SY5555 in dry syrup resulted in respective maximum plasma concentrations of 1.08 +/- 0.38 micrograms/ml (n = 4) and 2.50 +/- 1.81 micrograms/ml (n = 4), half-lives (T 1/2) of 2.72 +/- 1.86 hours (n = 3) and 1.14 +/- 0.88 hours (n = 4), and urinary excretion until 6 hours of 4.7% (n = 1) and 3.86 +/- 2.01% (n = 4). Clinical efficacy was evaluable in 22 patients, and the overall efficacy rate was 100%. As for bacteriological efficacy, all 5 strains of pathogenic organisms identified were eradicated (eradication rate, 100%). No remarkable adverse reactions or abnormal laboratory values were observed.

Evidence for the existence of vasopressin V2 receptor mRNA in rat hippocampus

Arginine-vasopressin (AVP) in the septum and hippocampus are thought to be involved in memory and learning, and their receptors have been classified into three subtypes, V1a, V1b and V2. In this study, we tested for AVP V1a- and V2-receptor mRNAs in the hippocampus of adult rats by a reverse transcription-polymerase chain reaction (RT-PCR) method. PCR product of the V2 receptor mRNA was detected in the hippocampus, but that of V1a receptor mRNA was not. This is the first demonstration of the existence of the V2 receptor mRNA in the hippocampus.

Cloning and analysis of the gene encoding lectin from the acorn barnacle Megabalanus rosa

In the acorn barnacle Megabalanus rosa, two types of galactose-binding C-type lectins (BRA-2 and BRA-3) have been identified. Here, we report the isolation and characterization of BRA-2 cDNA and genomic clones. In contrast to the BRA-3 gene, which consists of four exons, BRA-2 is encoded by a single exon, implying differences in the physiological roles of the two lectins.

[Pharmacokinetic and clinical studies of cefozopran in the field of pediatrics]

Cefozopran (CZOP) was administered intravenously to 22 infants (aged 3 months to 15 years) with infections excluding suppurative meningitis in doses of 10 to 40 mg/kg 3 to 4 times daily for periods of 3 to 16 days and its efficacy and safety in infantile infections as well as pharmacokinetic parameters were determined. The half-lives of CZOP after intravenous administration at doses of 10, 20 and 40 mg/kg were 2.84, 2.36 +/- 0.67, and 2.48 hours, respectively. The rates of recovery in the urine within 6 hours of administration were 83.6%, 62.9 +/- 23.1%, and 77.3%, respectively. The subjects for whom drug responses were evaluable consisted of 1 case of suppurative meningitis, 8 cases of respiratory tract infection, 2 cases of urinary tract infection, 2 cases of oral infection, 2 cases of pharyngotonsillitis, 1 case of skin soft tissue infection, and 1 case of external otitis, totaling 17 cases. The efficacy rate was 88.2%. The drug proved so effective on suppurative meningitis in particular that the patient was healed without leaving any sequela behind. Seven strains were identified as causative pathogens (5 strains of Haemophilus influenzae, 1 strain of Staphylococcus aureus, 1 strain of group B Streptococcus) isolated from 6 patients. All but 1 strain were eradicated (the rate of eradication 83.3%). In the patients with suppurative meningitis the bacterial count of spinal fluid was markedly decreased 6 hours after drug administration and the organism was eradicated in 45 hours. Eruption was noted in 1 patient as a side effect of CZOP, but disappeared soon after discontinuation.(ABSTRACT TRUNCATED AT 250 WORDS)

Guinea pig asthma induced by red soft coral (Dendronephthya nipponica) inhalation

Spiny lobster fishermen on the Pacific coast of Miyazaki Prefecture in Japan develop bronchial asthma due to occupational sensitization to red soft coral (Dendronephthya nipponica). To assess the role of sensitization in the development of bronchial hyperresponsiveness and the relationship between bronchial responsiveness and bronchial inflammation, we established a guinea pig model of red soft coral induced asthma. Twenty-four guinea pigs were intramuscularly immunized with a priming dose of red soft coral, 5 OD280 (15 mg protein) per 0.5 ml, and 0.5 ml complete Freund's adjuvant on day 1. Booster doses were repeated on day 15. By day 43 all sensitized animals showed high hemagglutination titers against red soft coral conjugated sheep erythrocytes and high IgG1 titers by passive cutaneous anaphylaxis. On day 43, the animals were challenged by inhalation of red soft coral extracts, 20 OD280 for 30 min. The respiratory resistance was monitored by the oscillation method. The respiratory resistance increased immediately upon inhalation in all sensitized animals and returned to baseline within 4 h. The bronchial reactivity to acetylcholine, measured 6 h after red soft coral inhalation in the sensitized animals when the respiratory resistance was returned to baseline, increased significantly (p < 0.05) as compared with the values measured 24 h before inhalation. The acetylcholine response measured 30 h later did not differ from preinhalation levels. There was a significant difference in the number of eosinophils (p < 0.001) in lamina propria and epithelium and of lymphocytes (p < 0.05) in the lamina propria 6 h after inhalation in the sensitized animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Residual Ca2+ and short-term synaptic plasticity

At many synapses, the amount of transmitter released by action potentials increases progressively during a train of spikes. This enhancement of evoked transmitter release grows during tetanic stimulation with several time constants, each bearing a different name (facilitation: tens to hundreds of milliseconds; augmentation: several seconds; potentiation: several minutes), and the enhancement of release to test spikes after a tetanus decays with similar time constants. All these processes depend on presynaptic Ca2+ influx during the conditioning tetanus. It has often been proposed that these forms of synaptic plasticity are due to residual Ca2+ present in nerve terminals following conditioning activity. We tested this idea directly by using photolabile Ca2+ chelators to reduce residual Ca2+ following conditioning stimulation or to generate an artificial elevation in Ca2+ concentration, and observed the effects on synaptic transmission at crayfish neuromuscular junctions. We found that facilitation, augmentation and potentiation are caused by the continuing action of residual Ca2+. Augmentation and potentiation seem to arise from Ca2+ acting at a separate site from facilitation, and these sites are different from the molecular target triggering neurosecretion.

Generation of hydrogen peroxide by varicella-zoster virus-stimulated polymorphonuclear leukocytes

BACKGROUND

In varicella-zoster virus (VZV) infections, the initial response in cutaneous lesions is predominantly polymorphonuclear leukocytes (PMN). However, interaction of VZV and PMN has not yet been fully defined.

OBJECTIVES

To explore the potential role of PMN in VZV infections, we investigated the ability of PMN to generate hydrogen peroxide (H(2)O(2)) after stimulation with VZV antigen.

STUDY DESIGN

H(2)O(2), one of the reactive oxygen species, was measured by cytofluorography after PMN were incubated with varicella-zoster virus (VZV) antigen in the presence of seropositive or seronegative serum.

RESULTS

H(2)O(2) was detectable in unseparated PMN obtained from seropositive children and adults, while unseparated PMN of seronegative donors were not capable of generating H(2)O(2). Separated PMN obtained from either seropositive or seronegative donors were capable of generating H(2)O(2) in the presence of seropositive serum. However, H(2)O(2) was not detectable in separated PMN of seropositive donors in the presence of seronegative serum. The of H(2)O(2) generation did not correlate with concentrations of serum antibodies to VZV.

CONCLUSIONS

VZV antigen-antibody complexes might induce H(2)O(2) generation by PMN.

Effect of varicella zoster virus antigen-antibody complexes on hydrogen peroxide generation by human polymorphonuclear leukocytes

Hydrogen peroxide (H2O2) generation by human polymorphonuclear leukocytes (PMN) incubated with varicella zoster virus (VZV) antigen was studied by cytofluorography. Hydrogen peroxide generation was detected in the presence of VZV-seropositive sera. When seropositive sera were heat-inactivated, H2O2 generation was reduced. When PMN were pre-incubated with Leu-11b, a monoclonal antibody to the Fc receptor on PMN, H2O2 generation was also reduced. These results suggest that VZV antigen-antibody-complement complexes induce H2O2 generation by PMN after these complexes attach to Fc receptors on PMN.

Impaired cell-mediated immunity to cytomegalovirus (CMV) in leukemic children with prolonged CMV viruria

To determine the role of cell-mediated immunity (CMI) to cytomegalovirus (CMV) in leukemic children after CMV infection, CMI to CMV antigen was studied using CMV-specific lymphocyte blastogenic responses (LBR) and interferon (IFN) production. Four children, who continuously secreted CMV in urine more than 2 years after symptomatic CMV infection (CMV disease) (group 1), showed impaired LBR to CMV antigen, though they had normal LBR to phytohemagglutinin (PHA) and concanavalin A (Con A). Impairment of LBR either to AD-169 strains or autologous and heterologous wild strains was observed. IFN production was not detected in three of four children. Six leukemic children, who had no viruria after cessation of CMV disease (group 2), showed good responses to CMV antigens. IFN was detected in all six children in group 2. Eight leukemic children, who were seropositive to CMV at the onset of leukemia (group 3), showed good responses to CMV antigens and IFN production. These results suggest that impaired cell-mediated immunity to CMV antigen might contribute to prolonged excretion of CMV in urine in leukemic children.

The mechanism of muscarinic agonist-stimulated inositol phosphate formation in permeabilized ileal smooth muscle

Muscarinic agonists and guanylyl-5'-imidodiphosphate (Gpp(NH)p) stimulated formation of inositol phosphates in permeabilized longitudinal smooth muscle of guinea pig ileum. Gpp(NH)p markedly potentiated the formation of inositol bisphosphate (IP2) and inositol trisphosphate (IP3) stimulated by carbachol, but increased inositol monophosphate formation (IP1) only slightly. Gpp(NH)p enhanced the formation of IP2 + IP3 induced by either acetylcholine or carbachol about fourfold in a synergistic manner, but enhanced the effects of oxotremorine and pilocarpine less than twofold in an additive manner. Elevation of Ca2+ concentration resulted in increases of the inositol phosphate levels stimulated by both carbachol and Gpp(NH)p. The optimal concentration of Ca2+ for carbachol-stimulated formations of IP2 + IP3 was shifted to a lower Ca2+ concentration in the presence of Gpp(NH)p. These findings suggest that muscarinic receptor-stimulated polyphosphoinositide hydrolysis in ileal smooth muscle results in inositol polyphosphate formation via GTP binding protein (G-protein). The muscarinic receptor-activated G-protein decreases the Ca2+ requirement of polyphosphoinositide hydrolysis. Muscarinic agonists stimulate inositol polyphosphate formation by interaction of the G-protein activation of a phosphoinositide specific phospholipase C with Ca2+ influx.

[Two cases of polymyositis with cardiac involvement]

Cardiac involvement in polymyositis is more prevalent than previously assumed. A 59-year-old and a 58-year-old man presented with cardiac involvement preceding skeletal muscular lesions, admitted because of increased levels of muscle-derived enzymes and left ventricular dysfunction with ECG abnormalities. Coronary angiography revealed no stenotic lesions. Right ventricular endomyocardial biopsy disclosed myocarditis. Left ventriculography showed local asynergy of cardiac wall motion. After admission the weakness and atrophy of skeletal muscles progressed gradually and high levels of muscle-derived enzymes persisted. Electromyography and skeletal muscle biopsy confirmed the clinical diagnosis of polymyositis. Both patients were diagnosed as having polymyositis with cardiac involvement, and treatment with steroids was started. Symptoms improved significantly, and the CK enzyme level was reduced effectively. The condition of one patient was well controlled, but the other suffered from repeated heart failure due to severe left ventricular dysfunction. The clinical spectrum of polymyositis is wide and variable. Further studies are needed to evaluate the detection, management, and prognosis of the disease as well as the pathogenesis and to prevent progression of cardiac involvement.

A flow cytometric method for measurement of hydrogen peroxide generation by pediatric polymorphonuclear leukocytes stimulated by Staphylococcus aureus and Escherichia coli

The generation of hydrogen peroxide (H2O2), one of the reactive oxygen species, by polymorphonuclear leukocytes (PMN) stimulated by Staphylococcus aureus and Escherichia coli was studied in infants by cytofluorography. After heparinized whole blood was incubated with bacteria for 60 min, generated H2O2 was measured. The positive rate of H2O2 generation of PMN and mean fluorescent intensity of positive PMN stimulated by S. aureus and E. coli were significantly reduced in infants aged < 1 year and H2O2 generation increased with advancing age. In 10-15 year old children, the level of generated H2O2 reached adult levels. When sera from 1 year old children were added to separated PMN from healthy adults, H2O2 generation was reduced. In contrast, H2O2 generation by PMN from 1 year old children was increased by the addition of adult sera. These results suggest that the ability to generate H2O2 in response to S. aureus and E. coli is lower in infants and that such reduced activity may be related to the susceptibility of such infants to S. aureus and E. coli infections.

Preparation of a photoactivatable fluorescent derivative of lactose and its application to photoaffinity labeling of a conger eel lectin

A photoactivatable heterobifunctional fluorescent reagent, 1-azido-5-naphthalene sulfonyl (ANS) hydrazide, was synthesized and characterized. ANS-hydrazide reacted with lactose to form a photoactivatable hydrazone. The derivative (ANS-lactose) had the same binding affinity for a conger eel lectin as lactose judging from the hemagglutinating-inhibition assay with rabbit erythrocytes. ANS-lactose was used for photoaffinity labeling of a conger eel lectin. The photolabeled lectin was digested with chymotrypsin to isolate photolabeled peptides by reversed-phase HPLC by monitoring fluorescence. A major labeled peptide was located at positions 31-45 in the lectin by amino acid analysis and N-terminal sequencing. The identified segment was close to the highly conserved region throughout animal beta-galactoside-binding lectins.

Vasopressin V1 receptor in rat hippocampus is regulated by adrenocortical functions

Two subtypes of arginine vasopressin (AVP) receptors (V1 and V2) have been distinguished. In this study, we examined the characteristics of AVP binding in rat hippocampus and the effects of bilateral adrenalectomy and adrenal steroids on its [3H]AVP binding. [3H]AVP binding to rat liver and the hippocampal membranes was strongly inhibited by the V1 antagonist, OPC-21268. ADX resulted in a significant decrease in the Bmax of AVP binding in the hippocampus. Chronic treatment with aldosterone and corticosterone restored the ADX-induced reduction, but treatment with dexamethasone did not. These results suggest that the AVP V1 receptor in the hippocampus is regulated by adrenocortical neuroregulatory functions.