Comparison of serotonin and 5-methoxytryptamine immunoreactivity in rat raphe nuclei

We studied the immunoreactivity of 5-methoxytryptamine (MT) and 5-hydroxytryptamine (HT) in the raphe region of rats using specific polyclonal antibodies and the peroxidase/anti-peroxidase (PAP) technique. Overall, the patterns of the specific staining for these two antibodies were found to be the same in this region of the rat brain. The staining reaction was considerably less intense for MT than for HT. Specificity tests were performed using HT, MT and tryptamine (T) conjugates at concentrations of 5 X 10(-8) M for antibodies to HT and 2.5 X 10(-9) M for antibodies to MT. Although the distribution of HT-like and MT-like immunoreactivity broadly overlapped, the results obtained from adsorption-specificity tests confirmed the presence of specific MT staining in the rat raphe.     

Glial uptake of monoamines in primary cultures of rat median raphe nucleus and cerebellum

Summary Glial uptake of serotonin and dopamine was studied in primary cultures of the median raphe nucleus and cerebellum by using consecutive demonstration of monoamine fluorescence and glial fibrillary acidic protein immunofluorescence. Most of the glial cells taking up monoamines were glial fibrillary acidic protein positive. Astrocytes with a strong immunoreactivity exhibited monoamine fluorescence only occasionally, although such cells did take up L-dopa readily. Glial fibrillary acidic protein negative cells — morphologically identified as astrocytes — were seen to exhibit monoamine fluorescence after exposure. Glial uptake of serotonin at a concentration of 10^–4 M was detected in cerebellar cultures but not in cultures from the median raphe nucleus. When the concentration was 10^–3 M uptake of serotonin took place in both the areas but was weaker in cultures from the median raphe nucleus. At concentrations greater than 10^–5 M glial uptake of dopamine was detected in cultures from both the regions studied. No region dependent differences in glial uptake of dopamine was demonstrated, however. Based on these observations astrocytes and astrocyte-like glial cells take up dopamine and serotonin. Also glial cells with a remarkably high content of the glial fibrillary acidic protein are more resistant to monoamine uptake than cells exhibiting less intense or no glial fibrillary acidic protein immunofluorescence. The existence of regional differences in uptake of serotonin between the median raphe nucleus and cerebellum suggests that glial uptake of monoamines is not an entirely passive mechanism but may be actively controlled by glial cells in a region dependent manner.     

Insulin receptor binding from mid-term and full-term placentas of patients with gestational diabetes mellitus and normal pregnant women

Insulin receptor binding was examined in the microvillous membranes of mid-term (20–22 weeks of gestation, MT) and full-term (FT) placentas from patients with gestational diabetes mellitus (GDM) and in normal pregnant control (N). Mid-term placentas were obtained from patients who have had spontaneous abortion. The maximum per cent specific binding (%SB) in MT placenta for GDM was significantly lower (4.8%) compared with the FT placenta (22%, p<0.001), while in the N group the maximum per cent specific binding for MT placenta was 14.1% compared with 26% for the FT placneta (p<0.001). Binding data from FT placenta of well-controlled GDM patients were similar with the FT placenta from N group (22%SB for GDM VS 26% SB for N). Even as there were similarities in the binding characteristics of FT placentas from both groups the placental membrane protein content in the GDM group was lower by 50% compared with the N control (2.5±0.11 VS 4.8±0.15 mg protein/g placenta respectively, p<0.001) suggesting that in the GDM group achieving a tight glycemic control could improve receptor affinities. Data from the competitive binding assay of GDM patients showed that the insulin necessary to achieve 50% inhibition (ID₅₀) was significantly lower in MT compared with the FT placenta (0.9×10^–9 M VS 3.8×10^–9 M, p<0.001) but in the N placenta there was no alteration in the ID₅₀ of MT and FT placentas (3.1×10^–9 M VS 4×10^–9 M, p<0.01, respectively). The present study demonstrated that in GDM the placental insulin receptor binding was significantly lower in spontaneously aborted placenta compared with placentas collected at full-term. Furthermore, these data suggest that the objective to achieve a tight glycemic control in GDM patients could optimize insulin receptor function similar to that of a normal pregnancy. Thus a full term placenta from GDM patients under a well managed glycemic control throughout the entire duration of pregnancy would result in an optimum insulin receptor function.     

Effect of reserpine on 5-hydroxytryptophan (5HTP)-immunoreactive neurons in the rat brain

By immunohistochemistry of rat brain in conjunction with a specific antibody against 5-hydroxytryptophan (5HTP), we examined immunoreactivity to 5HTP in neurons, from which 5-hydroxytryptamine (5HT; serotonin) was depleted by reserpine treatment. The distribution patterns of 5HTP-positive neurons overlapped with those of 5HT neurons. Treatment with reserpine (5 mg/kg, 90 min before death) caused a complete suppression of 5HT-positive staining, but 5HTP-immunostaining remained in perikarya of the nuclei raphe dorsalis, centralis superior and obscurus. Treatment with reserpine (25 mg/kg, 90 min before death) suppressed the 5HTP-immunoreaction in certain perikarya (e.g. of the nucleus raphe dorsalis) and fibres; however, 5HTP-immunostaining remained in perikarya of the nuclei centralis superior and raphe obscurus. This suggests that these neurons synthesize more 5HTP by a process which appears to be stimulated by reserpine.     

Immunofluorescent localization of insulin-like material in the median neurosecretory cells of the blowfly,Calliphora vomitoria (Diptera)

Summary Immunocytochemical staining has shown that the median neurosecretory cells (MNC) of the brain of the blowfly, Calliphora vomitoria, contain an insulin-like material which cross reacts with antibodies to bovine insulin. There are 24–26 paraldehyde fuchsin-positive MNC of which only 6–8 show the specific insulin-like immunoreactivity.Dr. M.C. Thorndyke, Department of Zoology, Bedford College, London University, kindly provided us with fluorescence facilities, and we are also grateful to him for helpful discussions on the immunofluorescence procedure     

Zinc compounds inhibit osteoclast-like cell formation at the earlier stage of rat marrow culture but not osteoclast function

The effect of zinc compounds on osteoclast-like cell formation in rat marrow culture in vitro was investigated. The bone marrow cells were cultured for 7 days in -minimal essential medium containing a well-known bone resorbing hormone (1, 25-dihydroxyvitamin D₃ and parathyroid hormone [1–34]). Osteoclast-like cell formation was estimated by staining for tartrateresistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of 1, 25-dihydroxyvitamin D₃ (10^–8 M) or parathyroid hormone (PTH; 10^–8 M) induced a remarkable increase in osteoclast-like multinucleated cells (MNC). These increases were clearly inhibited by the presence of zinc sulfate or zinc-chelating dipeptide (-alanyl-L-histidinato zinc; AHZ) in the concentration range of 10^–7 to 10^–5 M. The inhibitory effect was seen at the earlier stage of osteoclast-like MNC formation. However, zinc compounds (10^–6 M) did not have an effect on PTH (10^–8 M)-induced osteoclast-like cell formation in the presence of EGTA (5 × 10^–4 M), dibucaine (10^–5 M) or staurosporine (10^–9 M). Moreover, when osteoclasts isolated from rat femoraldiaphyseal tissues were cultured for 24 h in the presence of zinc compounds (10^–7 to 10^–5 M), the compounds did not have an effect on cell numbers or lysosomal enzymes activity (acid phosphatase and -glucuronidase) in the cells. The present study clearly demonstrates that zinc compounds inhibit osteoclast-like cell formation at the earlier stage with differentiation of marrow cells.     

Regucalcin modulates hormonal effect on (Ca2+−Mg2+)-ATPase activity in rat liver plasma membranes

The interaction of various hormones and regucalcin on (Ca²⁺–Mg²⁺)-ATPase activity in rat liver plasma membranes was investigated. The presence of epinephrine (10^–6–10^–4 M), and insulin (10^–8–10^– M) in the reaction mixture produced a significant increase in (Ca²⁺–Mg²⁺)-ATPase activity, while the enzyme activity was decreased significantly by calcitonin, (3×10^–8–3×10^–6 M). These hormonal effects, except for calcitonin, were clearly inhibited by the presence of vanadate (10^–4 M) which can inhibit the Ca²⁺-dependent phosphorylation of enzyme. Meanwhile, regucalcin (0.25 and 0.50 M), isolated from rat liver cytosol, elevated significantly (Ca²⁺–Mg²⁺)-ATPase activity in the plasma membranes, although this elevation was not inhibited by vanadate (10^–4 M). the epinephrine (10^–5 M) or phenylephrine (10^–4 M)-induced increase in (Ca²⁺–Mg²⁺)-ATPase activity was disappeared in the presence of regucalcin; in this case the effect of regucalcin was also weakened. However, the inhibitory effect of calcitonin (3×10^–6 M) was not weakened by the presence of regucalcin (0.5 M). Moreover, GTP (10^–5 and 10^–4 M)-induced increase in (Ca²⁺–Mg²⁺)-ATPase activity was not seen in the presence of regucalcin (0.25 M). The present finding suggests that the activating mechanism of regucalcin on (Ca²⁺–Mg²⁺)-ATPase is not involved on GTP-binding protein which modulates the receptor-mediated hormonal effect in rat liver plasma membranes.     

Dopamine and serotonin effects on neurons of dorsal root ganglion isolated from rats

The effects of 1×10^–8–1×10^–5 M dopamine (DA) and serotonin (HT) on membrane potential, input resistance (R_M), and action potential (AP) when added to the superfusing fluid for 0.5 min were investigated in perfused dorsal root ganglia (DRG) neurons isolated from 30–36-day old rats during experiments using intracellular recording techniques. Application of DA induced reversible changes in membrane potential in 48 out of 52 test cells as compared with 38 out of 44 for HT. Distribution of different patterns of response to DA and HT was similar: depolarization was recorded in 64.6 and 73.7% and hyperpolarization in 16.7 and 15.8%; two-stage response occurred in 18.7 and 10.5% of responding cells, respectively. Both monoamines induced reversible change in the AP and R_M pattern in a number of cells. Depolarization was accompanied by a decline and hyperpolarization by a rise in R_M. Both substances were found to affect mainly those neurons with electrophysiological properties characteristic of small cells. The possibility of afferent spike train modulation at the level of primary sensory neurons is suggested.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian USSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 5, pp. 644–651, September–October, 1989.     

Serotonin-induced changes in the excitability of cultured antennal-lobe neurons of the sphinx moth Manduca sexta

The modulatory actions of 5-hydroxy-tryptamine (5HT or serotonin) on a morphologically identifiable class of neurons dissociated from antennal lobes of Manduca sexta at stages 9–15 of the 18 stages of metamorphic adult development were examined in vitro with whole-cell patch-clamp recording techniques. Action potentials could be elicited from approximately 20% of the cells. These cells were used to examine effects of 5HT (5 × 10^–6 to 5 × 10^–4 M) on cell excitability and action-potential waveform. 5HT increased the number of spikes elicited by a constant depolarizing current pulse and reduced the latency of responses. 5HT also led to broadening of action potentials in these neurons and increased cell input resistance. Modulation of potassium channels by 5HT is likely to contribute to these responses. 5HT causes reversible reduction of at least 3 distinct potassium currents, one of which is described for the first time in this study. Because effects of 5HT on antennal-lobe neurons in culture mimic those observed in situ in the brain of the adult moth, in vitro analysis should contribute to elucidation of the cellular mechanisms that underlie the modulatory effects of 5HT on central olfactory neurons in the moth.     

Localization of carbonic anhydrase in the rat lung

Summary The localization of carbonic anhydrase in the rat lung has been demonstrated, at light and electron microscopic levels, by the cobalt bicarbonate histochemical method of Hansson. Focal deposits of the cobalt sulfide reaction product were found not only in the capillary endothelium of the alveolar walls, but also in the small and large alveolar cells. The histochemical reaction was abolished by two potent inhibitors, acetazolamide (10^–5 to 10^–6 M) and KCNO (5×10^–3 to 10×10^–3 M). Physiological assay with Maren's method indicated that values for carbonic anhydrase activity in rat lung are 4.4±0.8 UA/mg of protein, 25.0±5.5 UA/mg of nitrogen, and 369±86 UA/g of wet weight. In addition, it was calculated that after fixation in glutaraldehyde-formaldehyde-picric acid about 9% activity is retained.     

4-Bromoacetamidoprocaine: An affinity ligand for brain muscarinic and nicotinic cholinergic receptors

This study describes the synthesis, receptor binding characteristics, and some behavioral effects of p-bromoacetamidoprocaine (BAP), a new affinity ligand for brain muscarinic and nicotinic cholinergic receptors. The reversible binding of [³H]QNB to rat brain membranes was inhibited in a concentration dependent and saturable manner by both procaine and BAP, with Ki values of 4×10^–6 and 3×10^–7 M, respectively, and complete inhibition at 1×10^–5 M. Both procaine and BAP, although at much concentrations, inhibited the binding of [³H]methylcarbamylcholine in a concentration dependent manner, with Ki values of 5×10^–5 and 1×10^–5 M, respectively, and complete inhibition for both at 1×10^–3 M. Plots of the % irreversible inhibition of [³H]QNB, [³H]nicotine, and [³H]MCC vs [BAP] yielded Ki values of 7×10^–8, 1×10^–4, and 6×10^–5 M, respectively. In behavioral studies BAP was able to antagonize the QNB-induced hyperactivity in mice; however, BAP did not appear to alter nicotine-induced seizure activity or other behavioral effects in mice. A plot of the time course of inhibition by BAP for [³H]QNB binding revealed that the inhibition was almost complete within 10 min exposure at 37°. The findings indicate that BAP is a useful affinity ligand for examining the biochemical and functional characteristics of brain cholinergic receptors, particularly the muscarinic which has an affinity near the nM concentration range.     

2,6-Diisopropylphenol,a general anesthetic,inhibits glutamate action on rat synaptosomes

2,6-diisopropylphenol (propofol), a general intravenous anesthetic, inhibits the glutamate-dependent Ca²⁺ entry in rat synaptosomes with an approximate IC₅₀ of 3.0×10^–5 M.Propofol, at concentrations above 10^–6M, also inhibits the ATP-dependent uptake of glutamate in the presence of Ca²⁺, with an approximate IC₅₀ of 3.5×10^–5M, while it only has a slight inhibitory effect on the release of glutamate. The ouabain-insensitive synaptosomal ATPase is strongly inhibited by propofol, with an IC₅₀ of about 2.5×10^–6M, at concentrations which do not affect the luciferase system.     

Binding parameters of monoclonal antibodies reacting with ovarian carcinoma ascites cells

Summary Binding parameters were determined for four mouse monoclonal antibodies reacting with three antigens on the surface of fresh human ovarian carcinoma ascites cells, under nearly physiological conditions. The object of these experiments was to aid in the selection of the optimal monoclonal antibodies for intraperitoneal immunotherapy. The number of antigenic sites per cell, the effective equilibrium association constant (affinity) and the half-life for dissociation were: for Ab MH99, 1.2×10⁶ sites/cell, (1.9–4.1)×10⁸M^–1, and 4 h; for Ab MX35, (3.2–4.1)×10⁵ sites/cell, (3.4–4.8)×10⁸M^–1, and >10 h; and for Ab MW207, 1.3×10⁵ sites/cell, (3.6–4.1)×10⁹M^–1, and 3.1 h, respectively. One of the antigens, MH99, is recognized by five different monoclonal antibodies, and competitive inhibition experiments demonstrated that two distinct determinants are present; this antigen is also recognized by the previously described Ab 17-1A. These binding data will aid the rational design of immunotherapy strategies.     

Time course and auxin sensitivity of cortical microtubule reorientation in maize roots

Summary The kinetics of MT reorientation in primary roots ofZea mays cv. Merit, were examined 15,30,45, and 60 min after horizontal positioning. Confocal microscopy of longitudinal tissue sections showed no change in MT orientation 15 and 30 min after horizontal placement. However, after 45 and 60 min, MTs of the outer 4–5 cortical cell layers along the lower side were reoriented. In order to test whether MT reorientation during graviresponse is caused by an auxin gradient, we examined the organization of MTs in roots that were incubated for 1 h in solutions containing 10^–9 to 10^–6M IAA. IAA treatment at 10^–8M or less showed no major or consistent changes but 10^–7 M IAA resulted in MT reorientation in the cortex. The auxin effect does not appear to be acid-induced since benzoic acid (10^–5M) did not cause MT reorientation. The region closest to the maturation zone was most sensitive to IAA. The data indicate that early stages of gravity induced curvature occur in the absence of MT reorientation but sustained curvature leads to reoriented MTs in the outer cortex. Growth inhibition along the lower side of graviresponding roots appears to result from asymmetric distribution of auxin following gravistimulation.Abbreviations EGTA ethylene glycol-bis(-aminoethyl ether) N,N,NN-tetraacetic acid - MTs cortical microtubules - QC quiescent center - MES/TRIS 2-(N-morpholino)ethanesulfonic acid/tris(hydroxymethyl)aminomethane - IAA indole-3-acetic acid - PBS phosphate buffered saline - PHEMD [60 mM Pipes (piperazine-diethanesulfonic acid), 25 mM Hepes (N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid), 10 mM EGTA, 2mM MgCl₂ pH7.0 adjusted with NaOH] containing 5% dimethyl sulfoxide     

Plant regeneration via somatic embryogenesis from protoplasts of Uganda cherry orange (Citropsis schweinfurthii)

Protoplasts isolated from embryogenic callus of Citropsis schweinfurthii (Engl.) Swing. & M. Kell were cultured in MT (Murashige and Tucker 1969) basal medium containing 5% sucrose supplemented with 0.0, 0.001, 0.01, 0.1 or 1.0 mg l^–1 BA, 0, 300, 600 or 900 mg l^–1 malt extract and 0.6 M sorbitol. The highest plating efficiency was obtained on MT basal medium containing 5% sucrose supplemented with 0.01 mg l^–1 BA and 600 mg l^–1 malt extract. MT basal medium containing 5% sucrose and supplemented with 0.01 mg l^–1 kinetin was found to be a medium suitable for the development of globular somatic embryos derived from protoplasts into heart-shaped somatic embryos with cotyledon-like structures. The highest percentage of shoot formation was obtained using 0.1 mg l^–1 GA₃. A complete protoplast to-plant system was developed for C. schweinfurthii, which could facilitate the transfer of nuclear and cytoplasmic genes from this species into cultivated Citrus through protoplast fusion.Abbreviations BA N⁶-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - FDA fluorescein diacetate - GA₃ gibberellin A₃ - ME malt extract     

Stimulatory effect of hormonal signaling factors on (Ca2+−Mg2+)-ATPase activity in rat liver plasma membranes: Cross talk with regucalcin

The effect of hormonal signaling factors on (Ca²⁺–Mg²⁺)-ATPase activity in rat liver plasma membranes was investigated. The presence of inositol-glycan (10^–7–10^–5M), dibutyryl cAMP (10^–4 and 10^–3M) or inositol 1,4,5-trisphosphate (IP₃; 10^–6 and 10^–5 M) in the enzyme reaction mixture produced a significant increase in (Ca²⁺–Mg²⁺)-ATPase activity. These effects were completely inhibited by the presence of vanadate (10^–4 M), an inhibitor of the enzyme phosphorylation, and N-ethylmaleimide (5×10^–3 M), a SH group modifying reagent. Meanwhile, regucalcin, a Ca²⁺-binding protein isolated from rat liver cytosol, increased the enzyme activity by binding to the SH groups of (Ca²⁺–Mg²⁺)-ATPase in liver plasma membranes. The presence of regucalcin (0.25 M) with an effective concentration completely inhibited the effect of inositol-glycan (10^–5 M) to increase (Ca²⁺–Mg²⁺)-ATPase activity, while the effect of dibutyryl cAMP (10^–3M) or IP₃ (10^–5M) was not altered. The inositol-glycan effect was not modulated by the presence of dibutyryl cAMP or IP₃. Now, the preincubation of the plasma membranes with regucalcin did not modify the effect of inositol-glycan on the enzyme activity, suggesting that regucalcin competes with inositol-glycan for the binding to the plasma membranes. The present results suggest that there may be a cross talk with regucalcin and hormonal signaling factors in the regulation of (Ca²⁺–Mg²⁺)-ATPase activity in liver plasma membranes.     

Taurine-activated currents in isolated neurons of the rat cerebellum

Taurine-activated currents were investigated in rat cerebellar neurons using techniques of voltage clamping at the membrane and intracellular perfusion. Activation of both chloride and calcium conductance at the membrane were produced by applying taurine to the membrane surface. The dose-response curve for taurine-activated current is in the 1×10^–4–1×10^–1 M concentration region. The dissociation constant of the taurine-receptor complex equals 2×10^–3 M. Activation of taurine-induced currents is a cooperative process: Hill's coefficient –2. It was found that bicuculline and strychnine exert a blocking action on taurine-activated currents, while pentobarbital and oxazepam potentiate taurine action.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 22, No. 6, November–December, 1990, pp. 780–786.     

Application of a polyamine-coated capillary to the separation of metallothionein isoforms by capillary zone electrophoresis

In this study a fused-silica capillary treated internally with a polyamine coating which reverses electroosmotic flow in the direction of the anode was evaluated for its ability to resolve metallothionein (MT) isoforms. Analysis of different MTs purified from liver and kidney tissue revealed the following numbers of putative isoform peaks resolved: rabbit (3–6); horse (3–5); rat (2–3), chicken (1); human MT-1 (5–6); sheep (4–5) and pig (4–5). The greater degree of MT isoform heterogeneity detected in this study using the polyamine-coated capillary suggested a higher resolving capacity for capillary zone electrophoresis conducted with this capillary compared to an uncoated one. Using the single isoform of chicken MT (cMT) as a reference standard, relative standard deviations of 2.53, 1.85 and 2.21% for peak migration time, area and height, respectively, were observed for eight consecutive runs. A standard curve for cMT established linearity (r² = 0.99) for integrated peak area over three log units of cMT concentration with a lower limit of detection estimated to be 5 μg/ml. Acetonitrile extracts of chick liver tissue homogenates were successfully analyzed for the presence of MT isoforms from both control and zinc-injected animals. Based on our initial evaluation, capillary zone electrophoresis using the polyamine-coated capillary appears to be a very useful analytical method for the separation and quantification of individual MT isoforms.     

Glomerular binding of angiotensin II in the rainbow trout,Salmo gairdneri

Summary Isolated glomeruli of the rainbow trout have been exposed in vitro to¹²⁵I-angiotensin II (0.88 × 10^–9 M) and binding sites located by light-microscopic autoradiography. These studies provide evidence of specific binding of angiotensin II by glomeruli. Binding was significantly inhibited by excess (10^–5 M) unlabelled angiotensin II, but a high degree of non-specific binding also occurred. The mammalian competitive antagonist, saralasin (3 × 10^–7 M) did not influence¹²⁵I-angiotensin II binding to fish glomeruli. Intense binding of¹²⁵I-angiotensin II was noted at the vascular pole of some glomeruli.     

Neurotransmitters regulate rhythmic size changes amongst cells in the fly's optic lobe

Axon calibre in monopolar cells L1 and L2 of the fly's lamina can change dynamically. Swelling by day, L2 exhibits a daily rhythm of changing size apparntly mediated by wide-field LBO5HT and PDH cells. L1/L2 axon profiles were measured planimetrically in the housefly, Musca domestica, from 1 m cross sections. Four hours after injecting 80–100 nl of 1.25 × 10^–4 M 5-HT into the optic lobe, L1's axon swelled but L2's did not, whereas 2.2 × 10^–5 M of PDH enlarged both axons. Similar to 5-HT, 1.63 × 10^–4 M histamine (the photoreceptor transmitter) enlarged L1 but not L2, mimicking light exposure, while 1.7 × 10^–4 M glutamate and 1.94 × 10^–4 M GABA both decreased L1 and L2. 2.5 × 10^–4 M of 5,7-dihydroxytryptamine decreased L2 and, somewhat, L1, an effect attributable to the loss of LBO5HT neurites. Twenty four hours after cutting LBO5HT and PDH commissural pathways, L1 and L2 both shrank. Apparently, L2's size depends on either LBO5HT or sufficient 5-HT, and L1 and L2 have different response ranges to 5-HT. Responses to PDH imply that daytime PDH release drives a circadian rhythm, enlarging L1 and L2.Abbreviations ERG electroretinogram - GABA -aminobutyric acid - PDH pigment-dispersing hormone - PDF pigment-dispersing factor - 5-HT 5-hydroxytryptamine - EM electron microscopy(ic)