Morphometric and biochemical evaluation of rat prostate and seminal vesicle following chemical sympathectomy with guanethidine.

Selective chemical sympathectomy of the internal genital organs of adult male rats was undertaken by chronic treatment with low doses of guanethidine. Biochemical and morphometric methods revealed that removal of sympathetic innervation prevents fructose secretion in the prostate and seminal vesicle, in addition to promoting reduced efficiency of delivery by the latter.     

S-100-immunoreactive nerves in the guinea-pig uterus with reference to ultrastructural correlations: Effects of chemical sympathectomy and pregnancy

Summary In the guinea-pig uterus, by use of an indirect immunofluorescence method, S-100 immunoreactivity was found to be restricted to nerves that corresponded in number, distribution and type to adrenergic axons and preterminals. With advancing pregnancy S-100 immunoreactivity completely disappeared in uterine tissue adjacent to a fetus, in parallel with an ultrastructural degeneration of the adrenergic innervation. In the cervix and the uterine horn devoid of a fetus, however, the number and distribution of S-100-immunoreactive nerves was seemingly unchanged and no ultrastructural changes were found in adrenergic nerves. In contrast, chemical sympathectomy produced by 6-hydroxydopamine did not change S-100 immunoreactivity of uterine nerves. These findings suggest that there are differences in the denervation effected by chemical and by pregnancy-induced sympathectomy. The latter probably represents a special type of adrenergic denervation by inducing a degeneration of Schwann cells in addition to destruction of neuronal structures. This may explain the differences in the speed of regeneration of uterine adrenergic nerves following the two types of denervation.     

Effects of SERM (selective estrogen receptor modulator) treatment on growth and proliferation in the rat uterus

Background  

Selective estrogen receptor modulators (SERMs) have been developed in order to create means to control estrogenic effects on different tissues. A major drawback in treatment of estrogen receptor (ER) positive breast cancer with the antagonist tamoxifen (TAM) is its agonistic effect in the endometrium. Raloxifene (RAL) is the next generation of SERMs where the agonistic effect on the endometrium has been reduced.     

Changes in cholinergic and noradrenergic nerves in the pregnant and postpartum uterus of the albino rat and guinea pig

The present study was undertaken to investigate the structural changes in both cholinesterase (ChE)-positive nerve fibers and adrenergic nerves with formaldehyde-induced fluorescence in pregnant and postpartum uteri of both the albino rat and guinea pig. Particular attention was directed to the relationship between these changes and the local factors associated with the growing fetus. ChE reaction was absent in the control and pregnant uterus of the guinea pig. In the albino rat, there were signs of degeneration in pregnancy. These were evidenced by vacuolation of large nerve trunks and the presence of focal segments with very faint reaction along the course of the nerve bundles. Myometrial segments from fetus-containing horns showed some fragmented nerve fibers, but at the same time some other normal ones. Most of the fine nerve bundles gave a weak reaction. Three weeks after delivery, multiple ChE fibers were found in the uterus of the albino rat. The normal appearance was, however, not regained and some nerve fibers were still fragmented. Noradrenergic (NA) nerve fibers were disintegrated and markedly reduced in number in the myometrium of the pregnant uterus of both the guinea pig and albino rat, particularly in the uterine horns that were distended by fetuses. The number of NA fibers was not significantly reduced in the tubal ends of the albino rat uterus. Three weeks after delivery, normal NA fibers were seen in the myometrium of both the albino rat and guinea pig uterus. Nerves with reduced fluorescence reaction were observed less frequently.     

Effects of bilateral splanchnic-nerve section and chemical sympathectomy on PACAP38 content in the rat adrenals.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a basic 38-amino acid regulatory peptide contained in the adrenal gland and involved in the control of its secretory activity. Bilateral splanchnic-nerve section caused in the rat a significant decrease in PACAP38 adrenal content and concentration, as measured by RIA. In contrast, chemical sympathectomy, obtained by administering newborn rats with 6-hydroxydopamine, was ineffective. Our findings support the view that splanchnic nerves play an important role in the control of rat adrenal function.     

Distribution of cholinergic and catecholaminergic nerves in the colon of the rat with aganglionosis.

We compared localization and distribution of putative cholinergic fibers by acetylcholinesterase and of adrenergic fibers visualized by the glyoxylic acid technique in the aganglionic segment using whole mount preparations of aganglionosis rat (AGR) and compared them with those of normal littermates. We also attempted simultaneous staining of acetylcholinesterase (AChE) and catecholamine fluorescence (C-F) on the same whole mount preparations to compare the differences in distribution pattern. All AGR used in this study had narrowed segments of the bowel extending from the distal ileum to the anus, and had no ganglion cells in these narrowed segments. In the intermuscular space, normally occupied with myenteric ganglion, of the narrowed distal colon and rectum, various sizes of nerve bundles and fibers reactive for AChE and C-F appeared to make coarse and irregular networks. These thick nerve bundles appeared to ascend to the proximal colon and disappeared in the cecum. In the distal ileum, almost totally absence of AChE positive nerve fibers, but a few fine C-F fibers, probably associated with blood vessels, were observed. By the method of simultaneous staining of AChE and C-F method in the whole mount preparations, the thick nerve bundles in the narrowed segments showed both of AChE positive and C-F positive. However, there were differences in peripheral fine nerve fibers in the segment; especially numerous perivascular C-F positive nerve fibers, but a few AChE positive ones were found. In the upper aganglionic narrowed segments, greatly diminished numbers of AChE positive and C-F positive nerve fibers were found in the circular muscle layer and in the submucosal layer. In the lower aganglionic narrowed segments, there were thick nerve bundles, forming irregular interlaced network. The role of these extrinsic nerve fibers in aganglionic segments is unclear.     

Effects of bilateral splanchnic-nerve section and chemical sympathectomy on PACAP38 content in the rat adrenals.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a basic 38-amino acid regulatory peptide contained in the adrenal gland and involved in the control of its secretory activity. Bilateral splanchnic-nerve section caused in the rat a significant decrease in PACAP38 adrenal content and concentration, as measured by RIA. In contrast, chemical sympathectomy, obtained by administering newborn rats with 6-hydroxydopamine, was ineffective. Our findings support the view that splanchnic nerves play an important role in the control of rat adrenal function.     

Effects of chronic metrifonate treatment on cholinergic enzymes and the blood-brain barrier

After an acute (4 h) treatment with an irreversible cholinesterase inhibitor organophosphate, metrifonate (100 mg/kg i.p.), the activities of both acetyl- and butyrylcholinesterase were inhibited (66.0-70.7% of the control level) in the rat brain cortex and hippocampus. There were no significant changes in the acetyl- and butyrylcholinesterase activities in the olfactory bulb, or in the choline acetyltransferase activity in all three brain areas. After chronic (2 or 5 week) metrifonate treatment (100 mg/kg daily i.p.), the activities of both cholinesterases were substantially inhibited in the rat brain cortex and hippocampus (15.8-31.8% of the control levels), but there was no inhibition of the choline acetyltransferase activity. Moreover, chronic metrifonate treatment did not have any effect on the distribution of the acetylcholinesterase molecular forms. In vitro, metrifonate proved to be a more potent inhibitor of butyryl- than of acetylcholinesterase in both the cortex and the hippocampus. In the hippocampus, the butyrylcholinesterase activity was twice as sensitive to metrifonate inhibition as that in the cortex (IC50 values 0.22 and 0.46 microM, respectively). The effects of chronic (5 week) metrifonate treatment on the blood-brain barrier of the adult rat were examined. The damage to the blood-brain barrier was judged by the extravasation of Evans' blue dye in three brain regions: the cerebral cortex, the hippocampus, and the striatum. No extravasation of Evans' blue dye was found in the brain by fluorometric quantitation. These data indicate that chronic metrifonate treatment may increase the extracellular acetylcholine level via cholinesterase inhibition, but it does not have any effects on the blood-brain barrier. Therefore, it appears reasonable to hypothesize that cholinesterase activities do not play a role in the blood-brain barrier permeability.     

Effects of chronic sympathectomy on vascular function in the human forearm.

To determine whether endothelial function is altered by chronic surgical sympathectomy, we infused ACh, isoproterenol, nitroprusside (NTP), and the nitric oxide synthase inhibitor NG-mono-methyl-L-arginine (L-NMMA) into the brachial arteries of nine patients 5-64 mo after thoracic sympathectomy for hyperhidrosis. Age- and gender-matched controls were also studied. Forearm blood flow (FBF) was measured by venous occlusion plethysmography. Lower body negative pressure was used to assess reflex vasoconstrictor responses. Tyramine, which acts locally and causes norepinephrine release from sympathetic nerves, was also administered via the brachial artery. FBF at rest was 2.5 +/- 0.4 ml x dl-1 x min-1 in the patients and 2.5 +/- 0.3 ml x dl-1 x min-1 in the controls (P = 0.95). The normal vasoconstrictor responses to lower body negative pressure were abolished in the patients. By contrast, tyramine produced dose-dependent vasoconstriction in the patients that was identical to that of controls. The dose-response curves to ACh were similar in patients and controls, with maximum values of 19.3 +/- 4.4 vs. 25.5 +/- 2.8 ml x dl-1 x min-1, respectively. L-NMMA reduced baseline FBF similarly and reduced the maximal FBF response to ACh in both groups (patients 8.9 +/- 3.5 vs. controls 9.7 +/- 2.5 ml x dl-1 x min-1). The vasodilation to isoproterenol was similar and blunted to the same extent in both groups by L-NMMA. The responses to NTP in patients and controls were similar and not affected by L-NMMA. We conclude that, in humans, chronic surgical sympathectomy does not cause major disruptions in vascular function in the forearm. The normal vasoconstrictor responses to tyramine indicate that there were viable sympathetic nerves in the forearm that were not engaged by LBNP.     

Maturation of negative and positive estrogen feedback in the prepubertal female rat

The development of estrogen feedback system on gonadotropin release during sexual maturation in female rats was studied. Animals (Wistar strain rats) were divided into 6 groups according to their ages; 10, 15, 20, 25, 30, and 35 days. Both LH and FSH levels in serum increased significantly in response to ovariectomy in all age-groups studied when measured one week postoperatively, though in the rats aged 10-15 days the increase in FSH following castration was only slight. In rats older than 25 days, the postcastration gonadotropin rise, calculated as a percent increase from the basal figure, decreased gradually with increasing age. Ovariectomized rats injected with estradiol benzoate (EB, 5 micrograms/100 g BW) showed significantly lower levels of both LH and FSH than those in castrated controls. However, the inhibitory action of EB on postcastration gonadotropin output was found to be relatively less effective in rats older than 25 days. Ovariectomized rats primed with EB were again injected with a 2nd dose of EB (5 micrograms/100 g BW) at noon 3 days after priming. The 2nd EB injection induced a significant rise in LH 6 h later in 30- and 35-day-old, though not in younger, animals. On the other hand, the FSH response to EB was markedly enhanced during days 15-25 of age. These results indicate that the estrogen negative feedback action on gonadotropin release is already operating in female rats at a very early age, and that the brain sensitivity to estrogen decreases slightly during the late prepubertal phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of chronic treatment with typical and atypical antipsychotic drugs on the rat striatum.

Human MRI studies have demonstrated that treatment with typical antipsychotics may increase the volume of the caudate nucleus while clozapine treatment is associated with either no change or a reversal of the previous volume increase. In this study four groups of seven rats were treated for 8 months with either the typical antipsychotic haloperidol, the atypical antipsychotic clozapine, the D2/D3 receptor antagonist raclopride, or vehicle (plain drinking water). Striatal sections were prepared using D1-like and D2-like receptor ligand autoradiography. Images (4-6 sections per rat, per ligand) were digitized and the area of the striatum was measured on each section. Rats treated with haloperidol did not have a larger mean striatum area than the control group on either D1- or D2-like ligand autoradiograms. Using the D2-like ligand autoradiograms, the clozapine treated animals had a smaller mean striatum area than the control group. Mean left striatum area was larger than mean right striatum area in each treatment group and in the control group. In contrast to the MRI findings reported in schizophrenia, the area of the striatum was not increased in rats treated with typical antipsychotic agents, but the clozapine-associated area reduction may parallel the clinical studies.     

Presence and distribution of cholinergic nerves in rat mediastinal brown adipose tissue.

Brown adipose tissue (BAT) is richly provided with sympathetic noradrenergic nerves but is believed to lack a parasympathetic nerve supply. Acetylcholine is the predominant transmitter of postganglionic parasympathetic nerves. The vesicular acetylcholine transporter (VAChT) resides in synaptic vesicles of cholinergic nerve terminals and is used as a marker for peripheral cholinergic nerves. We sought cholinergic nerves in rat BAT using VAChT immunohistochemistry (IHC) on cryosections of interscapular, cervical, mediastinal, and perirenal depots. Mediastinal BAT was the sole depot provided with putative parasympathetic perivascular and parenchymal cholinergic nerves. The absence of vasoactive intestinal peptide-positive nerves suggested their nature as pure cholinergic fibers. By confocal microscopy, both cholinergic and noradrenergic nerves were detected in mediastinal BAT. Cold exposure and fasting led to increased density of VAChT-positive fibers and of noradrenergic sympathetic nerves at morphometry. The unexpected double innervation of mediastinal BAT may explain the inhibitory influence on thermogenesis observed after systemic injection of muscarinic antagonists in rats, and raises questions about the physiological role of its cholinergic nerve supply.