[Pharmacological profiles of F-1322, a novel anti-asthmatic agent. (1). Mechanisms of action]

The pharmacological effects of N-[2-(4-(benzhydryloxy)piperidino)ethyl]-3-hydroxy-5-(3-pyridyl methoxy)-2- naphthamide (F-1322), a novel anti-asthmatic agent, was investigated in vitro. The results obtained were as follows: 1) In the isolated trachea of guinea pigs, F-1322 showed a markedly potent antagonistic action against the contraction induced by histamine, while it had little or no effect on 5-hydroxytryptamine-, acetylcholine-, leukotriene D4- or U-46619-induced contractions. 2) In rabbit platelets, F-1322 did not affect the platelet aggregation induced by platelet activating factor. 3) F-1322 significantly inhibited the thromboxane (TX) A2 synthetase (IC50 value: 1.7 x 10(-8) M) and 5-lipoxygenase (IC50 value: 9 x 10(-7) M) activities. 4) F-1322 had no effect on phospholipase A2, cyclooxygenase, Ca2+/calmodulin-dependent phosphodiesterase and phosphodiesterase activities. These in vitro studies suggest that the anti-asthmatic action of F-1322 is associated with histamine antagonism and an inhibitory action on TXA2 synthetase and 5-lipoxygenase activities.

Right side hepatic resection under right thoracoabdominal incision with special reference to a highly anatomical systematized method

The results of 31 right side hepatic resections approached through thoracoabdominal incision are described, with emphasis on the benefit of the approach and systematized liver resection. Regarding postoperative mortality rate (0%) and morbidity rate (32.3%), the thoracoabdominal approach for right side hepatic resection seemed as safe and effective as the conventional abdominal approach. Even though there were no significant differences in the complications, the fluctuation of alanine aminotransferase and the hospital stay, the average operation time for the right segmentectomy through the thoracoabdominal approach was 1.3 hours less (p = 0.0078) than that of the abdominal approach. Technically, this approach was accomplished in almost the same fashion as in the abdominal approach by the utilization of systematized hepatic resection. Thoracotomy itself was not more harmful than the abdominal approach, even in patients with impaired liver function. This combination could take the advantage of a shorter operation time.

Identification of two opaque2 modifier loci in quality protein maize

Genetic modifiers of opaque2 convert the soft, starchy endosperm of opaque2 maize mutants to a hard, vitreous phenotype, while maintaining the enhanced lysine content of the grain. Genetic analysis of F2 segregating seeds from crosses of opaque2 by modified opaque2 genotypes indicated that the modifiers are complex traits that act codominantly. We developed two different segregating F2 populations and mapped the modifier loci by restriction fragment length polymorphism (RFLP) analysis. A relationship was found between formation of vitreous endosperm and the locus encoding the gamma-zein storage protein, which maps near the centromere of chromosome 7. Endosperm modification was consistently associated with the presence of two rather than one gamma-zein gene at this locus. A second modifier locus was mapped near the telomere of chromosome 7L.

Muscle layer and regional differences in autonomic innervation and responsiveness to transmitter agents in swine myometrium

1. To clarify possible regional and muscle layer differences in adrenergic innervation of swine myometrium, functional, biochemical and histochemical experiments were performed on longitudinal (LM) and circular (CM) muscle isolated from non-pregnant uteri of 84 gilts. 2. Transmural stimulation (TMS) in the presence of propranolol evoked tetrodotoxin-sensitive contractions in a frequency-dependent manner (2-20 Hz) in LM and CM. The cornual LM contractions were attenuated by phentolamine (1 microM) and by guanethidine (10 microM) though unaffected by atropine (1 microM). Contractions in cervical LM were diminished by atropine but not by phentolamine, and the corpus LM contractions were reduced incrementally by atropine and phentolamine when added sequentially. In CM, the TMS-induced contractions were abolished by tetrodotoxin and atropine in all three regions. 3. In response to noradrenaline (NA) and acetylcholine (ACh), LM contractile intensity was the most potent in cornua, slightly weaker in the corpus and weakest in the cervix. CM was insensitive to NA, and contractile responses elicited by ACh indicated no regional variation. 4. NA content, significantly greater in LM than in CM, was most highly concentrated in cornual LM. Nerves exhibiting glyoxylic acid-induced histofluorescence occurred in both LM and CM, though more abundantly in LM and with notable density in the cornual LM. Cholinesterase activity, distributed evenly throughout the three myometrial regions studied, was more intense in LM than in CM. 5. These results show that, in swine myometrium, innervation in cornual LM is predominantly noradrenergic, cervical LM is mostly cholinergic, and throughout the myometrium the CM layers are principally cholinergic.

Structure-activity study of chicken calcitonin gene-related peptide (CGRP) on vasorelaxation in rat mesenteric resistance vessels

Structure-activity relationship of the chicken calcitonin gene-related peptide (cCGRP) was investigated and compared with human-alpha-CGRP (hCGRP) and rat CGRP (rCGRP) in the perfused mesenteric vascular beds of rats. In precontracted mesenteric vascular beds, cCGRP, hCGRP and rCGRP produced a concentration-dependent vasodilation. The vasodilator activities of cCGRP and rCGRP were equipotent and more potent than that of hCGRP. (Ala2,7)cCGRP and (Des-1-Ala)-alpha-deamino cCGRP were 100- and 10-fold less potent than cCGRP, respectively. However, cCGRP[1-36] reduced vasodilator activity. The cCGRP[8-37] produced a vasoconstriction. Both cCGRP[8-37] and hCGRP[8-37] caused parallel shifts of the concentration-response curves of rCGRP to the right, but both peptides did not affect the maximum response and vasodilator responses to isoproterenol, these peptides being equipotent antagonists (pA2 values: 7.6 and 7.4). In rat brain membrane preparations, cCGRP and its fragments and analogues, except for cCGRP[1-36], competed for specific binding sites with [125I]-hCGRP. These results suggest that cCGRP has a potent vasodilator activity for which the disulfide bridge at position 2 and 7 of cCGRP is an important site and that position 37 is necessary for the binding of the peptide to the receptor. Also, cCGRP[8-37] is a competitive CGRP-receptor antagonist.

Effects of KW-5092, a novel gastroprokinetic agent, on the delayed colonic propulsion in rats

The effects of KW-5092, [1-[2-[[[5-(piperidinomethyl)-2- furanyl]methyl]amino]ethyl]-2-imidazolidinylidene]propanedinitr ile fumarate, on the loperamide- or clonidine-induced delayed propulsion were determined in rats and compared with those of other gastroprokinetic agents. Administration of loperamide (0.3 mg/kg, s.c.) or clonidine (0.01 mg/kg, s.c.) induced delay of the evacuation time of the teflon ball, which had been inserted into the distal colon. The delayed evacuation was improved dose-dependently by KW-5092 at 3 to 10 mg/kg (p.o.) or higher. Neostigmine at 0.3 to 3 mg/kg (p.o.) and T-1815 at 1 to 100 mg/kg (p.o.) also improved the delayed ball evacuation. These results suggest that KW-5092 stimulates the delayed colonic propulsion.

[Immunohistological study of the nasal mucosa in latent allergic patients]

We studied the distribution of T lymphocyte subpopulations and EG2 positive cells in the inferior turbinates of subjects with latent nasal allergy by use of an immunohistochemical procedure. Five patients who had a positive skin test for house dust and one who had a positive skin test for Japanese cedar were studied. The specimens were frozen at -70 degrees C and sliced at 4 microns with a cryostat. The peroxidaseantiperoxidase method with monoclonal antibodies (CD4, CD8, EG2) was used to detect T lymphocyte subpopulations and activated eosinophils. Finally, the specimens were counterstained with Mayer's Hematoxylin. CD4 positive cells and CD8 positive cells were found mainly in the superficial layer of the lamina propria. In every subject, the number of CD4 positive cells dominated that of CD8 positive cells in the lamina propria. The ratio of CD4 positive cells to CD8 positive cells was 1.93, on average. This ratio was lower than the ratio typical of nasal allergy, but higher than the ratio of non-allergic normal controls. Though the number of EG2 positive cells was lower than the number typical of nasal allergy, EG2 positive cells were observed in every case. We speculate that latent nasal allergic reactions may develop in the inferior turbinates.

Pharmacological characterization of presynaptic calcitonin gene-related peptide (CGRP) receptors on CGRP-containing vasodilator nerves in rat mesenteric resistance vessels

Rat mesenteric arteries are innervated by calcitonin gene-related peptide (CGRP)-containing vasodilator nerves (CGRP nerves). This study investigated the presence of presynaptic CGRP receptors on CGRP nerves and the receptors' role in the regulation of CGRP release from these nerves. The rat mesenteric vascular bed was perfused with Krebs' solution containing 7 microM methoxamine plus 5 microM guanethidine to produce active tone and block adrenergic neurotransmission. In this preparation, periarterial nerve stimulation (PNS;2 Hz) and bolus infusion of CGRP (50 pmol) caused a decrease in perfusion pressure caused by vasodilation. Vasodilator response to PNS was abolished by 0.3 microM tetrodotoxin and by 1 microM human CGRP[8-37] (CGRP[8-37]), a CGRP receptor antagonist, which also abolished the response to bolus infusion of CGRP. Perfusion of CGRP (0.03-0.5 nM) dose-dependently inhibited vasodilator response to PNS, whereas it did not affect the response to bolus infusion of CGRP. The inhibitory effect of CGRP (0.3 nM) was antagonized by CGRP[8-37] (3 and 10 nM). Lower concentrations of CGRP[8-37] (1-10 nM) potentiated the vasodilator response to PNS, but higher concentrations (100 nM-1 microM) inhibited the response. The vasodilator response to bolus infusion of CGRP was dose-dependently inhibited by CGRP[8-37]. Eel calcitonin (5 and 50 microM), forskolin (0.01 and 0.1 microM), 3-isobutyl-1-methylxanthine (0.3 and 1 microM) and cyclic 8-bromo-adenosine 3':5'-monophosphate (10 and 100 microM) had no effect on the PNS-induced vasodilation. These results suggest that CGRP nerves are endowed with presynaptic CGRP receptors, which regulate CGRP release from the nerves via a negative feedback mechanism.

Effects of dorsal rhizotomy on depressor response to spinal cord stimulation mediated by endogenous calcitonin gene-related peptide in the pithed rat

The effects of acute and chronic dorsal rhizotomy on vasodilation induced by spinal cord stimulation were investigated in the pithed rat in vivo. Pithed rats were treated intravenously with hexamethonium (2 mg/kg/min) to block autonomic outflow, and mean arterial blood pressure was maintained at approximately 100 mm Hg with methoxamine (10 to 15 micrograms/kg/min). Electrical stimulation (2 or 4 Hz, 10 V, 1 msec) of the lower thoracic spinal cord (T9-12) via the pithing rod caused a frequency-dependent depressor response without a change in heart rate. The depressor response to spinal cord stimulation was inhibited by the intravenous administration of human calcitonin gene-related peptide (CGRP) [8-37] (60 nmol/kg/min) or tetrodotoxin (100 micrograms/kg). In the pithed rat with acute or chronic bilateral dorsal root rhizotomy at lower thoracic levels (T8-12), spinal cord stimulation at 2 and 4 Hz caused no depressor response. These results suggest that the depressor response to spinal cord stimulation is mediated by endogenous CGRP, which is released from CGRP-containing nerves. The present results also suggest an outflow of CGRP-containing nerves from the spinal cord via the dorsal roots.

Intracerebroventricular treatment with vasopressin V1-receptor antagonist inhibits centrally-mediated pressor response to clonidine in conscious rats

The effect of intracerebroventricular (i.c.v.) treatment with a vasopressin (AVP) V1-receptor antagonist on the pressor response to i.c.v. injection of clonidine was investigated in conscious rats with chronic i.c.v. guide cannulas and an arterial catheter. In conscious rats, i.c.v.-injected clonidine (5 and 10 micrograms) dose-dependently produced a pressor response with a decrease in heart rate. No significant depressor response was induced by clonidine. The i.c.v. pretreatment with an AVP V1-receptor antagonist ([d(CH2)5-Tyr(Me)]-AVP) at 0.5-2.5 micrograms dose-dependently inhibited the pressor response to 10 micrograms of i.c.v.-injected clonidine, while systemic (i.v.) pretreatment with the antagonist (2.5 micrograms) had no effect. In pentobarbital-anesthetized rats, 10 micrograms of i.c.v.-injected clonidine caused a marked depressor response associated with bradycardia. However, i.c.v. pretreatment with the antagonist (2.5 micrograms) did not affect cardiovascular responses to i.c.v.-injected clonidine. These results suggest that endogenous AVP in the brain is involved in the mechanisms underlying the pressor response to i.c.v.-injected clonidine in conscious rats.

[Immunohistological study of eosinophilic infiltration of nasal polyps in aspirin-induced asthma]

It is well known that nasal polyps frequently develop in patients with aspirin-induced asthma, which is thought to be a non-atopic disease. We immunohistochemically examined the eosinophils infiltrating the nasal polyps in patients with aspirin-induced asthma. It has also been established that the monoclonal antibody EG1 reacts with both stored and secretion type ECP (eosinophil cationic protein), and that EG2 reacts only with the secretion type of ECP. EG2 positive cells may thus be considered to be activated eosinophils. Seven cases with nasal polyps associated with aspirin-induced asthma participated in our study. Blood eosinophilia was observed in all 7 cases, but 6 showed normal blood values IgE. Two reacted to house dust antigen, on skin tests and RAST. In the nasal polyps, many EG2 positive cells were observed. On serial sections, the number and distribution of EG1 and EG2 positive cells were almost equal. In the superficial lamina propria, extra-cellular release of ECP was noted. However, epithelial damage did not relate to the number of EG2 positive cells or the degree of extra-cellular EG2 release. In the deep lamina propria, slight extra-cellular ECP release was found. From these results, the eosinophils in nasal polyps accompanying aspirin-induced asthma were thought to be activated. Eosinophils seem to play an important role in the development of nasal polyps. However, tissue injury induced by eosinophils, was not be demonstrated in this study.

Pressor response to microinjection of clonidine into the hypothalamic paraventricular nucleus in conscious rats

We have reported that intracerebroventricular (i.c.v.) injection of clonidine causes pressor response in conscious rats. To determine the effective brain site, cardiovascular responses induced by unilateral microinjection of clonidine into various hypothalamic nuclei of conscious rats were studied. Microinjection of clonidine (5-20 micrograms/0.5 microliter) into the paraventricular nucleus (PVN) of conscious rats dose-dependently produced a long-lasting pressor response with a decrease in heart rate, which mimicked the response to i.c.v. injection of clonidine. However, clonidine (10 micrograms) injection into various hypothalamic nuclei (anterior, posterior, ventromedial and dorsomedial nucleus) caused a small or no pressor response. In anesthetized rats, clonidine injected into the PVN induced a long-lasting depressor response concomitant with bradycardia. PVN pretreatment with the alpha 2-adrenoceptor antagonist, yohimbine (1 and 10 micrograms), dose-dependently inhibited the pressor response to PVN injected clonidine, but the alpha 1-adrenoceptor antagonist, prazosin (1 microgram), had no significant effect. Central (i.c.v.) pretreatment with the vasopressin (AVP) V1-receptor antagonist, [d(CH2)5Tyr(Me)]-AVP (0.5 and 2.0 micrograms), dose-dependently inhibited the pressor response to PVN injection of clonidine (10 micrograms), while systemic (i.v.) and local (intra-PVN injection) pretreatments with V1-receptor antagonist (2.0 micrograms) had no effect. These results suggest that the pressor response to microinjection of clonidine into the PVN of conscious rats is mediated by endogenous brain AVP, which is released by activation of alpha 2-adrenoceptors. It is also suggested that the PVN is a possible brain site for the pressor response to i.c.v. injected clonidine.

Hepatitis C virus antibody in patients with primary liver cancer (hepatocellular carcinoma, cholangiocarcinoma, and combined hepatocellular-cholangiocarcinoma) in Japan

BACKGROUND

In hepatocellular carcinoma (HCC), a high prevalence of hepatitis C virus antibody (anti-HCV) has been reported, indicating that it may be an important etiologic factor in the pathogenesis of HCC. In this study, the authors investigated the prevalence of anti-HCV in HCC patients, as well as the same prevalence in patients with cholangiocarcinoma (CC) and combined hepatocellular-cholangiocarcinoma (combined HCC-CC), to study the clinicopathologic features of anti-HCV-positive cases.

METHODS

The authors examined 141 patients with primary liver cancer who were pathologically diagnosed as having HCC (121 cases), CC (13 cases), or combined HCC-CC (7 cases). Hepatitis B surface antigen (HBsAg) and anti-HCV were measured in these patients.

RESULTS

Of 121 HCC cases, 85 (70.3%) were found to be anti-HCV positive, 16 (13.2%) were HBsAg positive, and 5 (4.1%) were both anti-HCV and HBsAg positive. In 13 cases with CC and in 7 with combined HCC-CC examined, 4 (30.8%) and 5 (71.4%), respectively, were anti-HCV positive.

CONCLUSIONS

The anti-HCV-positive rate was high in combined HCC-CC as well as in HCC. These three types of primary liver cancer, which were anti-HCV positive, shared two common features: male dominance and high incidences of complication with liver cirrhosis.

[Immunohistologic study of the nasal mucosa with reference to Langerhans cells]

The distribution of Langerhans cells in human oral mucosa, nasal mucosa and nasal polyps was studied by means of immunohistochemistry. Our study involved 35 participants. The specimens were frozen to -70 degrees C and sliced at 4 microns with a cryostat. Monoclonal antibodies CD1 (OKT6) and the peroxidase-antiperoxidase staining method were used to detect Langerhans cells. In the oral mucosa and the nasal vestibule lined with stratified squamous epithelium, CD1 positive cells were observed and these cells were dendric in form. The cells were found mainly from the intermediate layer to the deep layer of the epithelium. In the inferior turbinate lined with ciliated epithelium, we could not find any CD1 positive cells at all. The nasal polyps in some cases had a normal ciliated columnar epithelium while others had metaplastic stratified squamous epithelium. Both types of epithelium in the same polyp were noted on some occasions. In nasal polyps, CD1 positive cells which showed dendric form were found in the metaplastic squamous epithelium only, and could not be observed in the ciliated columnar epithelium at all. Based on the above results, the presence of Langerhans cells is confirmed not by the anatomical location but by the type of epithelium. Langerhans cells could be detected only in the squamous epithelium. Keratinocytes, which constitute the squamous epithelium, are known to release cytokines. IL-1 (interleukin-1) and GM-CSF (granulocyte-macrophage colony stimulating factor) released from keratinocytes are thought to influence the viability and function of Langerhans cells. The migration of Langerhans cells into squamous epithelium may be regulated by cytokines released from keratinocytes.

Hepatitis C virus antibody in patients with primary liver cancer (hepatocellular carcinoma, cholangiocarcinoma, and combined hepatocellular-cholangiocarcinoma) in Japan

BACKGROUND

In hepatocellular carcinoma (HCC), a high prevalence of hepatitis C virus antibody (anti-HCV) has been reported, indicating that it may be an important etiologic factor in the pathogenesis of HCC. In this study, the authors investigated the prevalence of anti-HCV in HCC patients, as well as the same prevalence in patients with cholangiocarcinoma (CC) and combined hepatocellular-cholangiocarcinoma (combined HCC-CC), to study the clinicopathologic features of anti-HCV-positive cases.

METHODS

The authors examined 141 patients with primary liver cancer who were pathologically diagnosed as having HCC (121 cases), CC (13 cases), or combined HCC-CC (7 cases). Hepatitis B surface antigen (HBsAg) and anti-HCV were measured in these patients.

RESULTS

Of 121 HCC cases, 85 (70.3%) were found to be anti-HCV positive, 16 (13.2%) were HBsAg positive, and 5 (4.1%) were both anti-HCV and HBsAg positive. In 13 cases with CC and in 7 with combined HCC-CC examined, 4 (30.8%) and 5 (71.4%), respectively, were anti-HCV positive.

CONCLUSIONS

The anti-HCV-positive rate was high in combined HCC-CC as well as in HCC. These three types of primary liver cancer, which were anti-HCV positive, shared two common features: male dominance and high incidences of complication with liver cirrhosis.

[Pharmacological profile of F-0401, a novel dihydropyridine derivative. (1) Mechanisms of action]

F-0401 is a novel dihydropyridine (DHP) derivative with potent vasodilative and anti-aggregatory actions. In the present study, we examined the mechanisms of the actions of F-0401 and obtained the following findings: F-0401 suppressed [3H]nitrendipine binding to rat heart membrane (Ki value: 2.2 x 10(-7) M). CaCl2-induced contractions of rabbit aorta and guinea pig taenia coli were inhibited by F-0401 (pA2 values: 7.7 and 6.6). These results indicated that F-0401 had calcium antagonistic activity slightly less potent than that of the other DHP derivatives. In addition, F-0401 significantly inhibited the activity of thromboxane (TX) A2 synthetase (IC50 value: 2.5 x 10(-7) M) and [3H]PAF binding to rabbit platelets (Ki value: 1.4 x 10(-8) M). The other DHP derivatives tested did not affect TXA2 synthetic activity, and the PAF antagonism of the other derivatives were less than that of F-0401. Neither F-0401 nor the other DHP derivatives inhibited cAMP- or cGMP-dependent phosphodiesterase activity. These results revealed that F-0401 has calcium antagonistic, anti-PAF and TXA2 synthetase inhibitory actions in the same dose ranges.

Inhibition by indomethacin of the already accelerated secretion of inhibin and estradiol in equine chorionic gonadotropin-primed immature female rats

In immature female rats, the secretion of ovarian inhibin and estradiol is greatly accelerated by equine chorionic gonadotropin (eCG) treatment. The present study has been carried out to determine whether or not the levels of the two hormones are inhibited by a single s.c.-injection of indomethacin (INDO) 24 h after eCG administration. The levels of ovarian hormones and gonadotropins were measured by double-antibody radioimmunoassay using 125I-labeled radioligands. The serum levels of inhibin and estradiol were considerably inhibited within 24 and 12 h, respectively, after INDO injection. In addition, the serum levels of follicle-stimulating hormone (FSH) after INDO injection remained lower than the basal levels before eCG treatment. The luteinizing hormone (LH) levels were significantly reduced within 12 h after INDO treatment. The results demonstrate that the levels of inhibin and estradiol, even in the situation where the production of both hormones is already accelerated by eCG pretreatment, are suppressed by an inhibitor of prostaglandin (PG) synthesis, suggesting that locally produced PGs may play a role in the regulation of the production of both hormones in the ovary.

A role of prostaglandin in the secretion of inhibin and oestradiol-17 beta in equine chorionic gonadotrophin-primed rats

The role of prostaglandins in the secretion of inhibin and oestradiol-17 beta was examined in immature female rats treated with equine chorionic gonadotrophin. Administration of prostaglandin (PG) F2 alpha to animals whose serum and ovarian levels of inhibin and oestradiol-17 beta had been suppressed by indomethacin given 24 h after equine chorionic gonadotrophin prevented the inhibition or restored the levels to normal. Initiation of PGF2 alpha replacement immediately after treatment with indomethacin was more effective. The results are consistent with the hypothesis that PGs play a regulatory role in the synthesis and secretion of inhibin and oestradiol-17 beta by the rat ovary.

[Calcitonin gene-related peptide and neural control of vascular tone]

Rat mesenteric resistance blood vessels are innervated by nonadrenergic, noncholinergic (NANC) vasodilator nerves. In vitro pharmacological, biological and immunohistochemical studies have provided evidence that the calcitonin gene related peptide (CGRP), a 37 amino acid peptide translated by the calcitonin gene, has a potent vasodilator effect and acts as a vasodilator neurotransmitter for NANC vasodilator nerves. The CGRP-containing vasodilator nerves inhibit adrenergic nerve-mediated vasoconstriction through direct relaxation of vascular smooth muscle, while adrenergic nerves suppress the neurotransmision of CGRP-containing nerves by inhibiting CGRP release from the nerve. Thus, CGRP-containing nerves and adrenergic nerves control vascular tone with reciprocal interferences. In in vivo studies, spinal cord (T9-12) stimulation of pitched rats produced a NANC depressor response mediated by endogenous CGRP, suggesting that CGRP-containing nerves are regulated by the central nervous system. The malfunction of CGRP-containing vasodilator nerves may be involved in cardiovascular diseases such as essential hypertension, coronal vasospasm, cerebral vasospasm and Renaud's phenomenon. It is suggested that the CGRP-containing vasodilator nerves play an important role in the regulation of vascular tone.

Indomethacin inhibits the secretion of inhibin and oestradiol-17 beta stimulated by pregnant mare serum gonadotrophin in the immature female rat

The involvement of prostaglandins (PGs) in the regulation of inhibin and oestradiol-17 beta secretion from the ovary was studied by determining the effects of indomethacin and/or pregnant mare serum gonadotrophin (PMSG) on the levels of ovarian hormones in immature female rats. An increase in serum and ovarian levels of inhibin and oestradiol-17 beta was observed with a reciprocal reduction in serum follicle-stimulating hormone (FSH) levels from within 26 to 50 h after a single injection of 5 IU PMSG (s.c.) when the rats were 26 days of age. Administration of indomethacin to suppress PGs synthesis, simultaneously with PMSG, resulted in a substantial reduction in the levels of ovarian PGF2 alpha and serum inhibin and oestradiol-17 beta, which were both enhanced by PMSG treatment, 24 h after treatment with drugs. Indomethacin also reduced the basal serum level of inhibin. In the indomethacin-treated animals, the serum level of FSH was significantly increased regardless of the treatment with PMSG, indicating that the negative feedback regulation between FSH and inhibin is operating in these animals. These results demonstrate the inhibitory effects of indomethacin on PMSG-enhanced inhibin and oestradiol-17 beta production, suggesting that PGs play a regulatory role in the secretion of inhibin and oestradiol-17 beta from the gonadotrophin-stimulated ovary.

Purinergic vasoconstrictor component revealed by moderate cooling in the isolated mesenteric vasculature of Sprague-Dawley rats

In the isolated mesenteric vasculature of rats, moderate cooling significantly augments the perfusion pressure responses to transmural field stimulation (TFS), whereas it depresses markedly TFS-induced endogenous norepinephrine (NE) release. Moderate cooling also reduces the perfusion pressure responses to exogenous NE. The present experiments, therefore, were performed to analyze further the mechanism of the augmented pressor responses to TFS during moderate cooling. NE release from the entire mesenteric vasculature was monitored along with the perfusion pressure response to periarterial nerve stimulation (4-14 Hz) at 37 or 24 degrees C. Prazosin (3 x 10(-8) M) abolished the pressor responses to TFS at 37 degrees C but not at 24 degrees C. Furthermore, prazosin abolished the pressor responses to exogenous NE at both temperatures. The TFS-induced pressor responses observed in the presence of prazosin at 24 degrees C were abolished by alpha, beta-methylene adenosine 5'-triphosphate (alpha, beta-Me ATP) (3 x 10(-6) M). alpha, beta-Me ATP significantly decreased the pressor responses to TFS at 24 degrees C but not 37 degrees C. Moderate cooling significantly augmented the vasoconstrictor response to alpha, beta-Me ATP per se. These drugs did not influence the TFS-induced endogenous NE release at either temperature. These results suggest that moderate cooling reveals that ATP or related purines released from sympathetic nerves act as cotransmitters in the isolated mesenteric vasculature of rats. That is, augmented pressor responses to TFS during moderate cooling appeared to be due, at least in part, to a purinergic component.

Endogenous calcitonin gene-related peptide mediates nonadrenergic noncholinergic depressor response to spinal cord stimulation in the pithed rat

The role of endogenous calcitonin gene-related peptide (CGRP) in the nonadrenergic noncholinergic depressor response to spinal cord stimulation was studied in the pithed rat in vivo. Pithed rats were given hexamethonium (2 mg/kg per minute i.v.) to block autonomic outflow, and mean blood pressure was artificially maintained at approximately 100 mm Hg with methoxamine (10-15 micrograms/kg per minute i.v.). Electrical stimulation of the spinal cord at the level of the lower thoracic vertebra (T9-12) caused a fall in blood pressure in a frequency-dependent (0.5-10 Hz), voltage-dependent (2.5-50 V), and pulse duration-dependent (0.25-8 msec) manner. The heart rate did not change during the depressor response. The depressor response was long lasting, and the maximum response was elicited by stimulation at 4-6 Hz. The neurotoxin tetrodotoxin (100 micrograms/kg i.v.) abolished the depressor response to spinal cord stimulation, whereas treatment with propranolol (0.5 mg/kg per minute i.v.), atropine (0.05 mg/kg per minute i.v.), or a combination of pyrilamine (0.5 mg/kg per minute i.v.) and cimetidine (0.5 mg/kg per minute i.v.) did not affect the response. In pithed rats treated with capsaicin (total dose of 500 mg/kg s.c.), spinal cord stimulation caused a slight depressor response. Exogenous CGRP, but not acetylcholine, isoproterenol, histamine, or substance P, caused a sustained fall in blood pressure that mimicked the spinal cord stimulation-induced depressor response. Continuous infusion of CGRP[8-37] (60 nmol/kg per minute i.v.), a CGRP receptor antagonist, markedly inhibited the depressor responses not only to spinal cord stimulation but also to exogenous CGRP.(ABSTRACT TRUNCATED AT 250 WORDS)

Central alpha 2-adrenoceptor-mediated pressor response to clonidine in conscious, spontaneously hypertensive rats

Pressor responses to intracerebroventricular (i.c.v.) injection of clonidine were investigated in conscious spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Clonidine (1-10 micrograms, i.c.v.) caused a dose-dependent pressor response and decrease in heart rate in both SHR and WKY. In SHR, low doses (1, 2.5 micrograms) but not high doses (5, 10 micrograms) of i.c.v.-clonidine induced a depressor response following the pressor response. Both pressor and depressor responses to i.c.v.-clonidine were significantly greater in SHR than in WKY. In both SHR and WKY, pressor responses to i.c.v.-clonidine were abolished by pentobarbital anesthesia, pretreatment with i.v.-furosemide (5 mg/kg), 24-hr water deprivation and pretreatment with i.c.v.-yohimbine (100 micrograms), but not by pretreatment with i.v.-yohimbine (100 micrograms) and i.c.v.-prazosin (10 micrograms). On the 1st day after surgery for arterial catheter implantation, SHR reduced their water intake, and i.c.v.-clonidine (5 micrograms) caused a slight pressor response, whereas the same dose of clonidine on the 7th day after surgery resulted in a marked pressor response. These results suggest that clonidine caused a central alpha 2-adrenoceptor-mediated pressor response, which is greater in SHR than in WKY and is sensitive to body fluid volume changes and anesthesia.

Vascular contraction in perfused carotid arteries of cholesterol-fed rabbits

The purpose of the present study was to investigate the effects of hypercholesterolemia on sympathetic vascular responsiveness in the perfused rabbit carotid artery. Two groups of rabbit carotid arteries were evaluated for the simultaneous measurement of noradrenaline (NA) release and vasoconstrictor response induced by electric nerve stimulation and for exogenous NA-induced vasoconstriction in vitro. One group of rabbits was fed a diet containing 0.5% cholesterol for 2 weeks and the other group was fed standard rabbit chow. By scanning electron microscopy, monocytes adhering to the endothelial cells and penetrating into the subendothelium were observed. Neither endothelial denudation nor platelet adhesion could be detected. Rabbit carotid arteries were cannulated and perfused with a physiological solution at a constant flow rate. The vessels were subjected to both transmural field stimulation (TFS; 1.5-24 Hz) and exogenous NA administration. TFS caused a frequency-dependent increase in endogenous NA release with subsequent pressor responses in both groups. Exogenous NA also induced a dose-dependent pressor response, but a significant reduction was observed in the cholesterol-fed group. Methoxamine induced a similar response in both groups. It was concluded that hypercholesterolemia decreased the sensitivity of extrajunctional alpha-receptors in the perfused rabbit carotid artery.