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PubMed1992

Fate of microinjected genes in preimplantation mouse embryos.

The state of genes microinjected into mouse embryos was followed from the one-cell to the blastocyst stage using the polymerase chain reaction (PCR). Microinjected DNA was detected in all one-, two-, and four-cell injected embryos and in 44% of morula and 26% of blastocysts. Head-to-tail ligation of microinjected genes, a common feature of stably integrated transgene arrays, was detected in all embryos after injection of microinjected genes and occurred irrespective of the structure at the ends of the injected genes. Sensitivity of microinjected DNA to a methylation-dependent restriction endonuclease Dpn I was lost in all embryos by the two-cell stage (24 hr), indicating a change in DNA methylation, independent of transgene integration. Dissociation of blastomeres prior to compaction revealed a mosaic distribution of the microinjected DNA within the embryo and supports the notion that injected genes form a limited number of arrays, which segregate independently until they integrate into the genome or are degraded.

Animals↗

PubMed1985

Differential dysmorphogenesis induced by microinjection of an alkylating agent into rat conceptuses cultured in vitro.

A technique of microinjection of small quantities of teratogens into extraembryonic compartments or specific organ primordium of rat conceptuses of pregnancy day 11 is described. Conceptuses microinjected with 50 nl tissue culture medium developed normally for 44-45 hr when cultured in homologous rat serum, indicating that the microinjection procedure itself did not produce any deleterious effects on growth and differentiation of embryos. Microinjection of an alkylating agent, phosphoramide mustard dissolved in tissue culture medium, into the exocoelom produced anomalous embryogenesis, consisting of retarded embryonic growth, anomalies of the neural tube, and general necrosis of various organ primordia. In contrast, the embryonic development remained relatively unaffected by microinjection of identical amounts of this alkylating agent into the amniotic cavity. However, neural-tube differentiation was markedly affected when phosphoramide mustard was injected into anterior neural-tube fluid, producing anencephalic or microcephalic embryos without significant effect on postcephalic organ differentiation. The morphogenesis of the anterior limb was unaffected by local injection of the agent into somitic tissues adjacent to the presumptive limb-bud region. Therefore, it appears that differential dysmorphogenesis could be induced by microinjection of an alkylating agent into different conceptus compartments. These results indicate that even during early embryogenesis various cell types are not equally susceptible to a given teratogen, and that the differential cytotoxicity of the teratogen toward specific embryonic or extraembryonic cells and tissues may account for embryonic anomalies characteristically produced by that agent.

Abnormalities, Drug-Induced↗

PubMed1999

Microinjection of calpastatin inhibits fusion in myoblasts.

Rat satellite cells (RSC) were microinjected with purified calpastatin or m-calpain, and myoblasts from a C2C12 mouse line were microinjected with purified calpastatin. Microinjection with calpastatin completely prevented fusion of myoblasts from both sources, whereas microinjection with m-calpain significantly increased the rate of fusion of cultured RSC; 44% of the nuclei of RSC cultures were in multinucleated myotubes within 48 h after microinjection with m-calpain plus labeled dextran, whereas only 15% of the nuclei were in multinucleated myotubes after microinjection with dextran alone. Western analyses indicated that neither RSC nor C2C12 myoblasts contained detectable amounts of mu-calpain before fusion. The levels of calpastatin in C2C12 myoblasts increased as cells passed from the proliferative stage to the onset of fusion, and these levels increased substantially in both the C2C12 and the RSC cells as they progressed to the late or postfusion stage. Both RSC and C2C12 myoblasts contained an 80-kDa polypeptide that was labeled with an anti-m-calpain antibody in Western blots. The results are consistent with a role of the calpain system (m-calpain in these myoblast lines) in remodeling of the cytoskeletal/plasma membrane interactions during cell fusion.

Animals↗

PubMed2005

Increased transgene integration efficiency upon microinjection of DNA into both pronuclei of rabbit embryos.

Transgenic rabbits provide a useful biological model for the study of the regulation of mammalian genes. However, transgene integration efficiency has generally been low. Here we present a first attempt to increase the integration rate of exogenous DNA into the rabbit genome, using a double pronuclei microinjection method. Pronuclear stage rabbit embryos were recovered from superovulated NZW females, 19-20 h after hCG injection. About 5 microg/mL of exogenous DNA solution was microinjected either into one pronucleus (single microinjection, SM) or into both pronuclei (double microinjected, DM). The transgene consisted of a 2.5 kb murine whey acidic protein promoter (mWAP), 7.2 kb cDNA of the human clotting factor VIII (hFVIII), and 4.6 kb that of 3' flanking sequences of the mWAP gene. The in vitro survival of DM embryos to the blastocyst stage was lower than that of SM embryos (68 vs. 89%). Similar results were obtained using EGFP as a control gene construct. However, there was no difference in the percentage of embryos that developed into live offspring using DM (25%) vs. SM (26%). The integration frequency of mWAP-hFVIII into the genome of transgenic rabbits was 3.3% (1/30) upon SM and 8.1% (4/49) at DM (p < 0.05). All founders transmitted the transgene to their offspring in a Mendelian fashion. The SM founder female secreted 87.4 microg/mL rhFVIII in milk, with an activity of 0.594 IU/mL. The DM founder female produced 118 microg/mL rhFVIII, with activity values of 18 IU/ mL. This is the first report of transgenic rabbit production using a double microinjection technique. Our preliminary results suggest that this method can increase the efficiency of production of transgenic rabbit founders, giving a higher integration rate than single microinjection.

Animals↗

PubMed1986

Morphine microinjected into the periaqueductal gray has differential effects on 3 classes of medullary neurons.

The effects of microinjection of 5-10 micrograms of morphine into the midbrain periaqueductal gray (PAG) on the activity of neurons in the rostral ventral medulla (RVM) were studied in lightly anesthetized rats. Based on the relationship between changes in neuronal activity and the occurrence of the tail-flick reflex (TF), RVM neurons were divided into 3 groups: off-cells, on-cells and neutral cells. The off-cells exhibited an abrupt pause and the on-cells an acceleration beginning just prior to the occurrence of the TF. Neutral cell firing did not change at the time of the TF. Microinjections of morphine into the PAG which inhibited the TF had differential effects on the spontaneous activity of the 3 groups of neurons in RVM. Off-cells showed an increase and on-cells a decrease in spontaneous activity which preceded the inhibition of the TF. These microinjections also reduced the TF-related responses of off- and on-cells. The effects on cell activity were reversed by systemically administered naloxone and were not seen following microinjections which failed to block the TF. Neutral cell activity was unchanged following microinjection of morphine into the PAG. These results support the hypothesis that off- and on-cells in the RVM mediate the effects of microinjection of morphine into the PAG on spinal nociceptive reflexes.

Action Potentials↗

PubMed1991

Enkephalins, substance P and acetylcholine microinjected into the nucleus ambiguus elicit vagal bradycardia in rats.

Little is known about putative transmitters in the nucleus ambiguus (NA) mediating parasympathetic control of the heart, although Met-enkephalin (m-ENK), Leu-enkephalin (l-ENK), substance P (SP) and acetylcholine (Ach) have been detected in the cell bodies and fibers of this nucleus. The effects of these substances on arterial pressure (AP) and heart rate (HR) were studied by microinjecting them (4-20 nl) into the NA. Experiments were done in 26 spinal (high cervical) rats that were anesthetized with urethane and artificially ventilated. L-Glutamate (GLU) was microinjected into the right NA to identify the location of cell bodies from which decreases in HR and AP could be elicited. m-ENK, l-ENK, SP or Ach was then microinjected into these sites. Microinjection of 1 nmol of GLU elicited significant decreases in HR (-72.2 +/- 9.7 bpm, n = 15) which were not accompanied by significant decreases in mean AP. Microinjection of m-ENK (15-200 pmol; n = 7), l-ENK (15-200 pmol; n = 6), SP (0.9-15 pmol; n = 7) and Ach (2.0-20 pmol; n = 7) into the NA decreased HR in a dose-dependent manner but did not affect AP. The magnitudes of HR responses to m-ENK, l-ENK, SP and Ach were smaller but of longer duration than the changes in HR to microinjection of GLU. These results suggest a physiological role for GLU, enkephalins, SP and Ach in the vagal control of HR mediated by the NA.

Acetylcholine↗

PubMed1994

Cardiovascular effects of NaCl microinjections into the nucleus of the solitary tract.

The nucleus of the solitary tract (NTS) was systematically explored in the alpha-chloralose-anesthetized rat for sites that elicited changes in mean arterial pressure (MAP) and heart rate (HR) during microinjections (20 nl) of phosphate-buffered saline (PBS; pH 7.2-7.4) or NaCl solutions containing various concentrations of NaCl (104-326 mM). Decreases in MAP (range 7-83 mmHg) and HR (range 10-70 bpm) were consistently elicited from sites in the caudal medial and commissural subnuclei of NTS. Microinjection of PBS or NaCl into other NTS subnuclei or area postrema did not elicit cardiovascular responses. Microinjection of LiCl in PBS elicited cardiovascular responses that were significantly smaller than those elicited by microinjection of NaCl in PBS at the same NTS site. Injections of either a hyperosmotic (400 mOsm/kg) or a hyposmotic (204 mOsm/kg) solution of mannitol into NaCl-sensitive sites did not elicit cardiovascular responses. Finally, most of the sites in NTS that elicited cardiovascular responses during microinjection of glutamate (1 M) did not respond to microinjections of PBS. Administration of atropine methyl bromide had no effect on the magnitude of the depressor response to injections of PBS into NTS, but significantly attenuated (32%) the HR response. Subsequent administration of the ganglionic blockers hexamethonium bromide or arfonad abolished both the depressor and bradycardic responses. These data suggest that within a restricted region of the caudal NTS there exists a pool of neurons sensitive to changes in extracellular Na+ concentrations that, when activated by the sodium, elicit vasodepressor responses as a result of sympathoinhibition and bradycardia as a result of vagal excitation and sympathoinhibition.

Animals↗

PubMed1996

Cardiovascular effects produced by bradykinin microinjection into the nucleus tractus solitarii of anesthetized rats.

In this study, we characterized the cardiovascular effects produced by microinjection of doses in the femtomole range of bradykinin (BK) into the nucleus tractus solitarii of male Wistar rats (230-280 g, n = 120) anesthetized with urethane (1.2 g/kg, i.p.). Microinjections of BK (1, 10, 100 fmol, and 1 and 10 pmol, in 50 nl) or vehicle (NaCl, 0.9%) were made by using a triple-barreled glass micropipette into the medial nTS (0.4 mm anterior, 0.3 mm lateral to the obex and 0.3 mm deep from the dorsal surface). Microinjection of BK produced a shallow dose-dependent decrease in mean arterial pressure and heart rate reaching -18 +/- 6 mmHg and -21 +/- 5 beats/min, with the dose of 10 pmol. The peripheral mechanism of these effects, tested in animals treated with methylatropine (2 mg/kg, i.v.), or propranolol (2 mg/kg, i.v.) or prazosin (30 micrograms/kg, i.v.), was shown to be mainly dependent on an increase in vagal efferent activity for bradycardia and a decrease in sympathetic activity for hypotension. In order to investigate the receptor subtype involved in these effects, BK was microinjected into the nTS before and after the injection of the B1 receptor antagonist, Des-Arg9-Leu8-BK (DALBK) (11.5 pmol) or before and after the B2 receptor antagonist, HOE-140 (7.7 pmol). The cardiovascular effects of BK were significantly attenuated by the microinjection of HOE-140 and DALBK into the nTS. The effect of BK microinjected into the nTS on the baroreflex modulation was also investigated. While BK produced a significant facilitation of the baroreflex, HOE-140 and DALBK produced a significant attenuation of the baroreceptor control of heart rate. Taken together, the data presented in this study indicate the nTS as a site, in the central nervous system, for the modulatory effect of BK on the central cardiovascular control.

Anesthesia↗

PubMed1992

Cardiovascular effects of microinjections of quipazine into nuclei of the medulla oblongata in anaesthetized cats: comparison with L-glutamate.

Unilateral microinjections of quipazine (0.9 micrograms in 50 nl) into the subretrofacial nucleus produced hypertension and a slight tachycardia associated with an increase in renal sympathetic nerve activity. Microinjections of quipazine lateral, caudal or rostral to this nucleus failed to alter blood pressure and heart rate. Similarly, microinjections of l-glutamate (3 nmol in 15 nl) into the subretrofacial nucleus elicited hypertension, tachycardia and renal sympatho-excitation. The magnitude of the pressor response to quipazine was smaller than the response elicited by l-glutamate but its duration was longer. Microinjections of quipazine into the lateral tegmental field at l-glutamate hypertensive sites failed to alter arterial blood pressure and heart rate. In contrast, microinjections of quipazine into the caudal ventrolateral medulla or into the nucleus tractus solitarii produced hypotension and sympatho-inhibition. These effects were prevented by microinjections of the 5-HT2 receptor antagonists, LY 53857 or BW 501C. The present results indicate that stimulation of 5-HT2 receptors of the subretrofacial nucleus produces hypertension and sympatho-excitation whereas stimulation of 5-HT2 receptors in the caudal ventrolateral medulla and in the nucleus tractus solitarii produces hypotension and sympatho-inhibition.

Anesthesia↗

PubMed1986

Microinjection of monoclonal antibodies to vimentin, desmin, and GFA in cells which contain more than one IF type.

Microinjection of antibodies to vimentin into fibroblast cell lines causes intermediate filaments (IFs) to build perinuclear caps. We have extended these findings by microinjection of monoclonal antibodies specific for different IF types to non-epithelial cell lines of human origin, which co-express two different IF proteins. Thus GFA and vimentin IgGs have been microinjected in separate experiments into a glioma cell line, desmin and vimentin IgGs into RD cells, and vimentin IgGs into a cell line which co-expresses neurofilaments and vimentin. In all instances, microinjection of a single antibody causes the formation of perinuclear caps in which the two different IF proteins co-localize, suggesting that vimentin and the second IF type present in each cell line localize to the same 10-nm filaments. Immunoelectron microscopy using desmin and vimentin antibodies made in different species and appropriate second antibodies labelled with 5 and 20 nm gold particles confirm this result for RD cells. When Fab' fragments of the vimentin IgGs are microinjected into different cell types, formation of perinuclear caps is observed in immunofluorescence microscopy. In RD cells immunoelectron microscopy shows that the Fab' fragments induce caps which appear less dense than the caps seen after microinjection of IgGs.

Animals↗

PubMed1995

Pancreatic polypeptide, microinjected into the dorsal vagal complex, potentiates glucose-stimulated insulin secretion in the rat.

Specific binding sites for circulating pancreatic polypeptide (PP) have been found within the dorsal vagal complex (DVC) in the caudal medulla oblongata. Therefore, the effects of rat PP on pancreatic hormone secretion upon its microinjection into the DVC in halothane-anesthetized rats at doses of 0.4-40 pmol were investigated. At this range of doses, the changes in plasma concentrations of insulin, glucagon and glucose over basal levels did not differ from those after vehicle microinjection. In a separate series of experiments, vehicle and PP at doses of 0.4 and 4 pmol were microinjected into the right DVC 40 min after the continuous infusion of D-glucose had been started. In animals receiving continuous infusion of D-glucose, PP microinjected into the DVC (4 pmol), resulted in markedly higher insulin levels at corresponding time points compared to those with vehicle microinjected into the DVC. These data indicate, for the first time, that microinjection of PP into the DVC may potentiate glucose-stimulated insulin secretion in halothane-anesthetized rats.

Animals↗

PubMed1990

Suppression of a hind limb flexion withdrawal reflex by microinjection of glutamate or morphine into the periaqueductal gray in the rat.

Microinjection into the midbrain periaqueductal gray (PAG) or lateral reticular formation (LRF) of the neuronal excitant glutamate produces analgesia, and suppresses the responses of a fraction of spinal dorsal horn neurons to noxious heat applied to ventral hind paw skin. Microinjection of morphine into the PAG also produces analgesia, but has been reported to frequently facilitate, as well as to suppress or have no effect, on nociceptive spinal neurons. In anesthetized rats, we tested whether (a) glutamate microinjections into PAG or LRF, and (b) morphine microinjections into PAG, affected the isometric force of hind limb withdrawal elicited by the same noxious heat stimuli on the hind paw as used in single-unit studies of dorsal horn neurons. Glutamate (0.5 M; 0.1-0.5 microliter) microinjected at 9/12 PAG and 8/10 LRF sites suppressed the reflex, and had no effect or facilitated the reflex from the remaining sites. Morphine (5 micrograms in 0.5 microliter) microinjected at each of 10 PAG sites suppressed the reflex in a naloxone-reversible manner. Suppression usually began shortly after morphine, peaked at 20-40 min, and lasted greater than 60 min. The integrated flexion reflex thus appears to be more susceptible to chemical midbrain stimulation under these experimental conditions, compared to previous studies of single dorsal horn neurons.

Animals↗

PubMed1985

Reduction in RNA synthesis following red cell-mediated microinjection of antibodies to RNA polymerase I.

Antibody molecules directed against RNA polymerase I, the enzyme responsible for rRNA synthesis, were introduced into rat hepatoma cells by red cell-mediated microinjection. Access of the antibodies to the nucleolus, the site of rRNA synthesis, was facilitated by microinjecting mitotic cells. Using indirect immunofluorescence, anti-RNA polymerase I immunoglobulins, but not control immunoglobulins, were found localized in the nucleoli of microinjected cells. To assess whether intracellular antibodies could alter RNA synthesis, cultures were labeled with [3H] uridine at various times after microinjection. Reduction in RNA synthesis, relative to cells microinjected with non-immune immunoglobulins, was observed within three hours. These results demonstrate that antibodies introduced into the cytoplasm of mitotic cells via red cell-mediated microinjection have free access to nuclear components and that they remain functional within the nuclei of living cells.

Animals↗

PubMed2006

Autonomic and respiratory responses to microinjection of L-glutamate into the commissural subnucleus of the NTS in the working heart-brainstem preparation of the rat.

Changes in heart rate (HR), thoracic sympathetic nerve activity (tSNA) and frequency of phrenic nerve discharge (PND) in response to microinjection of L-glutamate before and after local microinjection of ionotropic or metabotropic glutamate receptors antagonists into the commissural subnucleus of the NTS (comNTS) were investigated. The experiments were performed in an in situ unanesthetized decerebrated working heart-brainstem preparation (WHBP), and the main findings were as follows: (a) microinjection of increasing concentrations of L-glutamate (5, 25, 50, 250 and 500 mM) into the comNTS produced bradycardia, increase in tSNA and reduction in the frequency of the PND in a concentration-dependent manner; (b) both bradycardia and increase in tSNA were almost abolished by kynurenic acid (KYN, 250 mM, a nonselective ionotropic glutamate receptor antagonist); (c) the reduction in the frequency of the PND was reversed to an increase in the frequency of the PND after KYN and this increase was blocked by the sequential microinjection of MCPG (100 mM, a nonselective metabotropic glutamate receptor antagonist); and (d) microinjection of increasing concentrations of trans-ACPD (0.5, 1.0, 2.5, 5.0 and 10 mM, a metabotropic glutamate receptor agonist), elicited bradycardia and increase in the frequency of the PND in a concentration-dependent manner, which were blocked by MCPG. Taken together, these data indicate that l-glutamate and its ionotropic receptors are involved in the sympathoexcitatory, bradycardic and reduction in the frequency of the PND responses whereas/although its metabotropic receptors are involved in the bradycardic and mainly in the increase in the frequency of the PND to microinjection of L-glutamate into the comNTS in the WHBP.

Animals↗

PubMed2004

High throughput easy microinjection with a single-cell manipulation supporting robot.

A single-cell manipulation supporting robot (SMSR) has been developed for the high throughput and easy microinjection. Its concept is to let an experimenter concentrate his/her attention only on the microinjection by facilitating other associated works. SMSR was applied to the microinjection into rice protoplasts and mouse embryonic stem (ES) cells. The microinjection into these cells is exceptionally difficult than usual animal cells such as fibroblasts. In the case of rice protoplast, for example, non-stop microinjection into 100 cells could be done within 1h that was 17-times faster than that of the robot-less work. The success rate was 7-8% that was same level obtained by the robot-less work. The present results indicate that SMSR is a useful machine for the microinjection of specific genes and proteins in living cells to analyze their respective functions, which is an urgent and important subject in the post-genome era.

Animals↗

PubMed1994

Embryo survival after pronuclear microinjection and trophectoderm biopsy.

OBJECTIVE: Our purpose was to compare murine embryo development after pronuclear microinjection of a gene construct, followed by trophectoderm biopsy at the blastocyst state, with development after a single micromanipulation, and with cultured controls. STUDY DESIGN: alpha-Myosin heavy-chain gene sequence was microinjected into the murine embryo pronucleus and cultured to blastocyst. After trophectoderm biopsy the embryos were allowed to re-expand. Re-expanded embryos were transferred to pseudopregnant females; implantation and live birth rates were recorded. In this study group the rates were compared with three control groups of embryos simultaneously cultured after (1) pronuclear microinjection only, (2) trophectoderm biopsy only, and (3) non-micromanipulated, culture only. RESULTS: A total of 1222 embryos were divided among the four groups. In the study group 472 embryos underwent pronuclear microinjection and trophectoderm biopsy. Of these, 203 (43%) reached the blastocyst stage and underwent biopsy; 183 (38.8%) re-expanded after biopsy. Of 275 pronuclear microinjected only (control 1) embryos, 113 (41.1%) reached the blastocyst stage. Of 336 embryos 148 (44.0%) reached the blastocyst stage and underwent trophectoderm biopsy only (control 2); 129 (39.2%) survived biopsy. The cultured only group (control 3) consisted of 139 pronuclear embryos; 67 (48.2%) developed to the blastocyst stage. CONCLUSIONS: Murine embryos can survive two micro-manipulations, pronuclear microinjection followed by trophectoderm micro-biopsy. Although there is minimal effect of these procedures on embryonic development in vitro, the live birth rate is tenuous.

Animals↗

PubMed1997

GABA(A) and GABA(B) agonists and antagonists alter the phase-shifting effects of light when microinjected into the suprachiasmatic region.

GABAergic drugs have profound effects on the regulation of circadian rhythms. The present study evaluated the effects of microinjections of GABAergic drugs into the suprachiasmatic region in hamsters on phase shifts induced by light and by microinjection of a cocktail containing vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI) and gastrin-releasing peptide (GRP). The phase-advancing effects of light at circadian time (CT) 19 were significantly reduced by microinjection of GABA(A) or GABA(B) agonists into the SCN, but were not altered by microinjection of GABA(A) or GABA(B) antagonists. Microinjection of a GABA(B) agonist also reduced the phase-delaying effects of light at CT 13.5-14 while a GABA(B) antagonist increased the phase delays caused by light. Neither GABA(B) drug altered the phase delays produced by microinjection of a peptide cocktail containing VIP, PHI, GRP. These data indicate that changes in GABA(A) or GABA(B) activity within the SCN can alter the phase-shifting effects of light on circadian rhythms and support a role for GABA in gating photic input to the circadian clock.

Animals↗

PubMed1997

Cardiovascular effects of microinjections of opioid agonists into the 'Depressor Region' of the ventrolateral periaqueductal gray region.

Microinjections of excitatory amino acids made into the ventrolateral midbrain periaqueductal gray of the rat have revealed that neurons in this region integrate a reaction characterised by quiescence, hyporeactivity, hypotension and bradycardia. Microinjections of both excitatory amino acids and opioids into the ventrolateral periaqueductal gray have shown also that it is a key central site mediating analgesia. The effects of injections of opioids into the ventrolateral periaqueductal gray on arterial pressure and heart rate or behaviour are unknown. In this study we first mapped in the rat the extent of the ventrolateral periaqueductal gray hypotensive region as revealed by microinjections of excitatory amino acids. We found that ventrolateral periaqueductal gray depressor region extended more rostrally than previously thought into the tegmentum ventrolateral to the periaqueductal gray. Subsequently we studied for the first time, the effects of microinjections of mu-, delta-, and kappa-opioid agonists made into the ventrolateral periaqueductal grey depressor region. In contrast to the effects of excitatory amino acid injections, microinjections of the mu-opioid agonist ([D-Ala2,N-Me-Phe4,Gly-ol5]enkephalin) evoked hypertension and tachycardia at approximately 50% of sites. Similar to excitatory amino acid injections, microinjections of both the delta-opioid agonist ([D-Pen2,D-Pen5]enkephalin), and the kappa-opioid agonist ((5,7,8)-(+)-N-Methyl-N-[7-(1-pyrrolidinyl)-1-oxaspiro[4.5]dec-8-y l]-benzeneacetamide) evoked either a hypotension and bradycardia, or had no effect. These results indicate that different opiate receptor subtypes are present on a distinct population of ventrolateral periaqueductal gray neurons, or at different ventrolateral periaqueductal gray synaptic locations (pre- or post-synaptic).

Analgesics↗