The synaptology of neurotensin (NT)-, somatostatin (SS)- and vasoactive intestinal polypeptide (VIP)-immunoreactive neurons was studied in the central nucleus of the rat amygdala (CNA). Three types of axon terminals formed synaptic contacts with peptide-immunoreactive neurons in the CNA: Type A terminals containing many round or oval vesicles; Type B terminals containing many pleomorphic vesicles; and Type C terminals containing fewer, pleomorphic vesicles. Peptide-immunoreactive terminals were type A. All three types of terminals formed symmetrical axosomatic and asymmetrical axodendritic contacts. However, type B and peptide-immunoreactive terminals frequently formed symmetrical axodendritic synaptic contacts. VIP-immunoreactive terminals also formed asymmetrical axodendritic contacts. SS- and NT-immunoreactive terminals commonly formed symmetrical contacts on SS- and NT-immunoreactive cell bodies, respectively. VIP-immunoreactive axon terminals were postsynaptic to nonreactive terminals. Type B terminals appeared more frequently on VIP neurons than on NT or SS neurons.

Amygdala↗

PubMedDate not supplied

Computer-assisted image analysis of the distributions of peptidergic terminals in the central nucleus of the amygdala: a preliminary study.

When viewed under dark-field illumination, peptidergic terminals in sections stained by the Sternberger PAP immunocytochemical method are seen as individual points of light. Under high magnification, the degree of brightness of various areas of immunoreactive terminals is seen to be a function of the density of terminals in these areas. By analyzying the relative brightness of the immunostained central nucleus of the amygdala (CNA) with an EyeCom II PDP-11/34 image analysis system, we have obtained a relative evaluation of the density distribution of neurotensin (NT)-, substance P (SP), VIP-, angiotensin II (AII), m-enkephalin (m-ENK) and somatostatin (SS)-immunoreactive terminals in terms of normal morphology and following a brain lesion. The EyeCom II system divides the presented image into 307200 picture elements (pixels) and assigns one of 256 grey values to the average brightness with each pixel. We have aggregated the grey level frequencies into 5 levels where level 1 corresponds to the highest terminal density and level 5 to the lowest density. At level 1, only NT- and VIP-immunoreactive terminals occupy a significant percentage of the cross-sectional area of the CNA (20%). About 15% of the area of the CNA has VIP terminals with level 5 density. The distributions of the top 20% of the terminal density range of NT, SP, AII and VIP support a classical medial/lateral division of the nucleus. The distribution of the same range of SS- and ENK terminals suggests a dorsoventral division of the CNA. A preliminary study indicates that comparison of grey level frequency histograms generated by image analysis from homologous lesioned and unlesioned sections of the CNA can yield useful information regarding post-lesion changes in the distribution of immunoreactive terminals.

Amygdala↗

PubMedDate not supplied

The role of substance P-containing fibers in sympathetic ganglia: effect of capsaicin.

Capsaicin was given subcutaneously to guinea pigs and the effect on substance P-immunoreactive (SP-I) fibers in the celiac/superior mesenteric and inferior mesenteric ganglia was observed at 2 day and 8-10 day intervals. Capsaicin (125 mg) treatment led to almost total disappearance of SP-I fibers from all areas examined in both short- and long-term animals. This effect applied equally to the dense network of varicose SP-I fibers and to basket-like SP-I contacts with principal ganglionic neurons. The effect of capsaicin on SP-I fibers in the mesenteric ganglia provides a strong indication that these fibers represent a homogeneous population of visceral sensory afferents. This is supported by other lines of anatomical evidence in the literature. Taken together with studies that have shown axodendritic contact of SP-I terminals on principal ganglionic neurons and neuro-modulatory effects of SP on these neurons, it may be hypothesized that SP-I fibers in the mesenteric ganglia represent collaterals of visceral sensory afferents forming a subspinal feedback arc.

Animals↗

PubMedDate not supplied

Neurotensin immunoreactivity in the central nucleus of the rat amygdala: an ultrastructural approach.

Neurotensin (NT) was demonstrated in the central nucleus of the rat amygdala (CNA) using a modification of the avidin-biotin complex immunohistochemical technique. Electron-dense reaction product (particles were 15-25 nm in diameter) was localized in perikarya, dendrites, axons, and axon terminals. It was found also associated with profiles of rough endoplasmic reticulum, mitochondria, microtubules, and small agranular as well as large granular vesicles. In distal dendrites, the reaction product was associated with microtubules, vesicles, and postsynaptic densities. Axon terminals of three types formed synaptic contracts with NT-immunoreactive neurons in the CNA: one was characterized by numerous round or oval agranular vesicles, the second by numerous pleomorphic vesicles, and the third by agranular vesicles that were loosely distributed and pleomorphic. All three types formed symmetric axosomatic and asymmetric axodendritic contacts. NT-immunoreactive axon terminals containing small round agranular vesicles stood out clearly from the intermingling profiles of immunonegative structures. We found numerous glomeruli, each consisting of a central NT-immunoreactive dendrite surrounded by all three types of axon terminals. We observed that some NT-immunoreactive terminals formed symmetric axoaxonal contacts with each other, providing evidence for the presence of local NT-to-NT circuits, whereas many others synapsed with axon terminals devoid of NT immunoreactivity.

Amygdala↗

PubMedDate not supplied

Fluorescence microscopy used in conjunction with horseradish peroxidase localization and electron microscopy for studying sympathetic nuclei of the rat spinal cord.

After application of horseradish peroxidase (HRP) to the transected cervical sympathetic trunk, labeled sympathetic neurons were seen in the intermediolateral nucleus (IML), central autonomic nucleus (CAN) and intercalated nucleus of rat spinal cords. As studied by glyoxylic acid-induced histofluorescence microscopy (FM), catecholaminergic (CA) terminals were most densely packed in the IML. There were 60 +/- 2 CA varicosities per 2,200 mu2 area in 20 mu thick sections through the IML. A combined FM/HRP method confirmed that preganglionic sympathetic neurons are heavily innervated by CA terminals. CA boutons were tagged with 5-hydroxydopamine for EM identification, and in the IML, 56% of CA boutons were seen to make synaptic contacts as compared to 60% in the CAN. It seems likely that virtually all CA boutons may form synapses but serial sections through boutons were not studied. It is inferred that preganglionic sympathetic neurons of both IML and CAN are served by CA inputs, and electron microscopy has revealed that most or all of these CA terminals transmit their signals via synapses; which may permit more precise structural sorting than non-synaptic transmission.

Adrenergic Fibers↗

PubMedDate not supplied

The terminal innervation patterns in young and old guinea pig heart valves: a quantitative analysis using acetylcholinesterase staining.

The objective of this study was to determine whether and to what extent age-related changes occur in atrioventricular (AV) heart valve innervation. The AV valves from three young adult (3 months) and three older (> 24 months) female guinea pigs were studied. An acetylcholinesterase (AChE) localization method was used to prepare valve whole mounts for analysis. Two methods were used to assess nerve fiber density. Segments of the valves were drawn using a camera lucida/Nikon optiophot system. The density of nerve fibers was calculated from digitized images. The density of nerve fibers was also calculated by counting the points at which the nerve plexus intersected with the grid lines of an ocular graticule. In the bicuspid and tricuspid valves of the older guinea pigs, we observed a marked diminution in the densities of the nerve plexus, particularly in the basal zone, towards the free edges of the valve cusps, and in the chordae tendineae. Whole mount preparations such as those used in our morphological studies of the AV innervation may assist in elucidating the changes in other autonomic nerve plexuses with aging. Further work is required to establish whether and to what extent the loss of valve innervation influences the effectiveness of closure of the valves.

Acetylcholinesterase↗

PubMedDate not supplied

Inappropriate sexual behaviour experienced by speech-language therapists.

Inappropriate sexual behaviour by clients or patients of health professionals has been noted as a considerable problem in a number of professions. Similarly, sexual harassment by colleagues or employers has been identified as causing stress and harm. The primary objective of this study was to investigate the experience of speech-language therapists in New Zealand of inappropriate sexual behaviour (ISB) by colleagues, clients, and care givers of clients. A questionnaire developed by McComas and colleagues to investigate ISB directed by patients at physical therapists in Canada was adapted to meet the broader requirements of this study. This questionnaire was sent to all members of the New Zealand Speech-Language Therapists' Association and to current third- and fourth-year students in the Bachelor of Speech and Language Therapy degree programme in 1994. The overall return rate was 70%. A large number of respondents (81%) reported experiencing some level of ISB. The number of incidents of ISB from clients and colleagues was identified with equal frequency; care givers less frequently. Fewer students than qualified therapists reported ISB as sexual harassment. ISB affects work performance (e.g. absenteeism) and causes psychological reactions (e.g. stress). A majority of respondents reported being satisfied with how they handled ISB but considered there would be value in having training for both qualified and student therapists in managing such behaviour. Conclusions drawn from the study are that colleagues as well as clients are a serious source of ISB for qualified and student speech-language therapists; that negative effects in this group are similar to those in other professions; that speech-language therapists experience less ISB from clients than some other professions; and that, despite legal steps to curb sexual harassment, it continues to be an issue that requires local administrative and educative attention.

Adult↗

PubMedDate not supplied

The metabolism of [14C]rimantadine hydrochloride in rats and dogs.

Metabolism and route of excretion of [14C]rimantadine hydrochloride was studied in male rats after single po (60 mg/kg) and iv doses (15 mg/kg) and in male dogs (5 or 10 mg/kg po and 5 mg/kg iv). Total 14C excretion in urine (po and iv) in both species reached 81-87% of the dose in 96 hr. Rimantadine was excreted in rats free (1.0% po, 1.7% iv) and conjugated (0.8% of the dose, po and iv, both in 24 hr) and in dogs, free (2.6% po, 3.0% iv) and conjugated (6.4% po, 7.7% iv, both in 48 hr). In both species, rimantadine metabolism is essentially independent of the route of administration. In rats and dogs, m-hydroxyrimantadine (mostly unconjugated) was the major metabolite, 22% (po) and 24% (iv), and 27% (po) and 21% (iv), respectively. Rats, but not dogs, excreted trans-p-hydroxyrimantadine (23.5% and 25.2%, po and iv, free plus conjugated). An oxidative pathway in dogs produced the m- and p-hydroxylated analogs with a hydroxyl in place of the amino group (3.7% and 5.7% of the dose, both conjugated). A p-hydroxylated compound with a nitro group in place of the amino group may have originated from an N-hydroxy metabolite by spontaneous oxidation during isolation. Comparison of total 14C excretion, in rats (81%, po; 82%, iv) and dogs (81%, po; 84%, iv) after po and iv administration after 96 hr indicates good absorption of rimantadine.

Administration, Oral↗

PubMedDate not supplied

The disposition and metabolic fate of 14C-cibenzoline in man.

The disposition and metabolic fate of cibenzoline (CBZ) following single oral 153-mg doses of 14C-CBZ succinate were studied in five healthy adult males. The mean maximum plasma radioactivity of 386 ng eq/ml occurred at 2.4 hr after administration. The mean half-life, determined from the 14C plasma concentration and urinary excretion rate data, was 13.1 and 14.8 hr, respectively. The mean maximum CBZ concentration was 196 ng/ml at 1.2 hr post-dose. The mean half-life, determined from the plasma concentration and urinary excretion rate data, was 7.2 and 7.3 hr, respectively. The mean total clearance of radioactivity and CBZ was 300 ml/min and 1224 ml/min, respectively, due to elimination via both renal and nonrenal pathways. The only unconjugated metabolite in the plasma was 4,5-dehydrocibenzoline which, together with other unidentified metabolites, is presumed responsible for the longer observed half-life for total radioactivity. Approximately 75% of the dose was recovered in the urine in the first 24 hr after dosing, 80% of which was present at CBZ and known metabolites. After 6 days, a mean of 85.7% of the dose was excreted in urine and 13.2% in feces. The predominant excreted compound was CBZ (55.7% of the dose) in the 0-72 hr urine. Although several metabolites were identified in urine samples, none were found in substantial amounts relative to the parent drug. Two of these substances showed slight antiarrhythmic activity, whereas the 4,5-dehydro metabolite, representing approximately 4% of radioactivity in urine, was inactive.

Adult↗

PubMedDate not supplied

The metabolism of 14C-cibenzoline in dogs and rats.

The disposition of the new antiarrhythmic agent cibenzoline (CBZ) (racemic 4,5-dihydro-2-(2,2-diphenylcyclopropyl)-1H-imidazole) in three male dogs was investigated after oral administration of 13.8 mg/kg of 14C-CBZ base. Within 6 days, 60.5 +/- 6.0% of the dose was excreted in urine and 19.2 +/- 4.6% in feces. In 0-24-hr urine, unchanged drug was excreted (41.6% of the dose) as well as the unconjugated 4,5-dehydro metabolite (DHCBZ, 3.7%), conjugated p-hydroxybenzophenone (0.8%, only in one dog), and a phenolic metabolite, p-hydroxycibenzoline (HCBZ) in a rearranged form (RHCBZ) at 5.2% of the dose (free plus conjugated). Studies with synthetic HCBZ indicated that unrearranged HCBZ was excreted and that rearrangement occurred during purification. CBZ from dog urine displayed slight optical activity, based on ORD/CD data, corresponding to an optical purity of 15% of the S-(-)-CBZ, indicating a limited extent of stereoselective metabolism of CBZ in dogs. After an oral 50-mg/kg dose of 14C-CBZ succinate, male rats excreted in 3 days 27.0 +/- 2.8% in urine and 41.5 +/- 2.6% of the dose in feces, and in a repeated experiment 32.1 +/- 1.9% in urine and 54.5 +/- 0.7% in feces. CBZ (7.6%) and DHCBZ (0.2%) were determined in 0-24-hr urine, and CBZ (4.2%) and RHCBZ (4.2% of the dose) were determined in 0-24-hr feces. RHCBZ (3.1%), m-methoxy p-hydroxycibenzoline (8.3%), and p-hydroxybenzophenone (5.3% of the dose) were identified as glucuronide/sulfate conjugates in bile from rats. Evidence that p-hydroxybenzophenone arose from an unstable unidentified metabolite is discussed.

Administration, Oral↗

PubMedDate not supplied

Identification of trimoprostil metabolites excreted in rat bile formed by oxidation and taurine conjugation.

14C-Trimoprostil was administered iv and orally to male rats. Radioactivity was excreted mainly via the feces after both routes of drug administration. Bile duct-cannulated rats excreted an average of 76% of an iv dose in the bile within 6 hr after dosing. Four biliary metabolites were isolated by HPLC and identified by proton NMR spectroscopy and mass spectrometry. These metabolites were taurine conjugates of: trimoprostil (approximately 11% of dose), 5,6-dihydro-2,3-dinor trimoprostil (approximately 5% of dose), 3,4-dehydro trimoprostil (less than 5% of dose) and 5,6-dihydro-2,3,4,5-tetranor trimoprostil (less than 5% of dose).

Animals↗

PubMedDate not supplied

Biotransformation of prochiral 2-phenyl-1,3-di(4-pyridyl)-2-propanol to a chiral N-oxide metabolite.

The prochiral compound, 2-phenyl-1,3-di(4-pyridyl)-2-propanol (PPP) labeled with 3H in the phenyl ring, was administered to rats, dogs, and a human subject. Paper chromatography of the urine indicated that a major metabolite common to all three species was excreted. This metabolite was isolated from the urine of chronically dosed dogs and was identified by mass, nuclear magnetic resonance (NMR), and infrared spectrometry as the N-oxide, 2-phenyl-1-(4-pyridyl)-3-(4-pyridyl-1-oxide)-2-propanol. In addition, polarimetry indicated that this metabolite was levorotatory. Examination of the enantiomeric purity of a crystallized sample of the metabolite by NMR spectroscopy of resolvable diastereomeric salts formed with lasalocid revealed the presence of only the levorotatory enantiomer. Accordingly, this metabolic N-oxide formation in the dog was at least stereoselective, and perhaps stereospecific. The N-oxidation of PPP was also demonstrated in vitro with 9000 g supernatant fraction of rat liver fortified with an NADPH generating system, and this reaction was inducible by phenobarbital, indicating that it is mediated by the cytochrome P-450 mixed-function oxidase system. This study, in addition to providing another example of the pyridyl N-oxidation pathway, illustrates the necessity of considering the stereochemical aspects of the metabolism of prochiral drugs.

1-Propanol↗

PubMedDate not supplied

The metabolism of 14C-methoxsalen by the dog.

Single doses of 14C-methoxsalen (5 mg/kg) were administered iv to three dogs. Almost as much administered radioactivity was excreted in the feces as in the urine, suggesting that biliary secretion of metabolites was an important route of excretion. 14C-Methoxsalen disappeared rapidly from plasma, although plasma levels of radioactivity persisted for 5 weeks after drug administration. Evidence was obtained which suggested that the persistent plasma radioactivity was due to a metabolite bound to plasma protein. Four urinary metabolites were isolated. Three of the metabolites resulted from opening of the furan ring; these are 7-hydroxy-8-methoxy-2-oxo-2H-1-benzopyran-6-acetic acid (A), alpha,7-dihydroxy-8-methoxy-2-oxo-2H-1-benzopyran-6-acetic acid (B), and an unknown conjugate of A at the 7-hydroxy position. The fourth metabolite, formed by opening of the pyrone ring, is an unknown conjugate of (Z)-3-(6-hydroxy-7-methoxybenzofuran-5-yl)-2-propenoic acid.

Animals↗