Lactic/glycolic acid polymers as narcotic antagonist delivery systems.

Lactic/glycolic acid polymers of several compositions were evaluated as the vehicle material for long term, controlled delivery of narcotic antagonists. L(+)-lactic, and glycolic acids-designated L(+), and G, respectively-were converted to polymers with weight ratios of 75 L(+)/25 G, 90 L(+)/10 G, and 100 L(+). Naltrexone base and naltrexone pamoate were incorporated into these polymers as a physical blend at several drug/polymer mass ratios. The mixtures were formed into small cylinders and spheres which were suitable for subcutaneous implantation by means of a trochar. $\text{In vitro}$ screening was carried out followed by $\text{in vivo}$ testing in mice. Radioactive assay and direct challenge with morphine using the tail-flick test were used to evaluate the drug release. The release rates approximated zero-order kinetics for most of the release period and the narcotic antagonist response to a challenge dose of morphine was maintained from one month to over six months depending on the formulation tested. Factors affecting narcotic antagonist delivery system design were polymer composition, narcotic antagonist solubility, drug loading level of the dosage form, use of a pure polymer coating around the drug/polymer matrix, and the surface area/unit volume of the dosage form.     

Acute inhibition of microsomal drug metabolism by propoxyphene in narcotic tolerant/dependent mice

Propoxyphene (Darvon) was compared to SKF 525-A, a prototypical inhibitor of hepatic microsomal mixed function oxidases, to assess propoxyphene's potential to inhibit drug metabolism in morphine tolerant/dependent mice. $\text{In vitro}$, both propoxyphene (K_i = 3.5 × 10^?5M) and SKF 525-A (K_i = 4.3 × 10^?6M) inhibited the activity of aminopyrine N-demethylase competitively in hepatic microsomes from tolerant/dependent animals. Propoxyphene and SKF 525-A were weaker, noncompetitive inhibitors of aniline hydroxylase activity. $\text{In vivo}$, equimolar doses (0.24 mmoles/kg, i.p.) of each compound inhibited both of the above monooxygenases in the 10,000$\text{g}$ supernatant fractions of livers from the tolerant/ dependent animals. Propoxyphene was 40–50% as potent an inhibitor of these activities as SKF 525-A. A dose (300 mg/kg) of propoxyphene napsylate, shown to prevent narcotic abstinence signs with no observable toxicity in withdrawing mice, significantly prolonged the blood levels of injected pentobarbital and tripled pentobarbital sleeping time in these animals. When administered at 300 mg/kg chronically, propoxyphene napsylate acted as an inducer of its own metabolism. Propoxyphene napsylate, then, given acutely to narcotic tolerant/dependent mice, is a potent inhibitor of microsomal drug metabolizing capacity. Given chronically, it enhances this capability.     

Dopamine-sensitive adenylate cyclase of the caudate nucleus of rats treated with morphine.

The addition of narcotic analgesics $\text{in vitro}$ to nerve ending preparations from rat caudate nucleus in an assay of adenylate cyclase activity (AC) resulted in an inhibition of basal AC only at drug concentrations of 10−⁴M or higher, and no inhibition of dopamine-stimulated (DA) AC at these drug concentrations. The acute administration of morphine at a moderately high dose (60 mg/kg) produced an increase in striatal cAMP levels, and increases in basal and DA-AC in caudate nerve-endings. In morphine-tolerant rats, striatal cAMP levels and basal AC were similar to control values, while DA-AC was elevated. These results suggest: (1) that opiates do not act directly on DA-AC, the ‘dopamine receptor’, and (2) that the observed behavioural DA sensitivity in tolerant animals may be produced by the DA-AC supersensitivity.     

Effects of yohimbine and naltrexone in counteraction of the morphine straub tail and the amphetamine-potentiated morphine straub tail in mice

The alpha-adrenergic blocking agent, yohimbine, prevented the production of the morphine Straub tail reaction in mice, although on a mg dose basis it was only about $\text{1}\text{400}$ as potent as the narcotic antagonist naltrexone by subcutaneous injection. Likewise, yohimbine prevented the potentiation of the morphine Straub tail reaction by amphetamine, being about $\text{1}\text{170}$ as active as naltrexone. Preliminary studies with another alpha-adrenergic blocking agent, phentolamine, indicated that it also inhibited the production of the Straub tail reaction by morphine, although it appeared to be somewhat weaker than yohimbine in this respect. These results suggest the involvement of alpha-adrenergic mechanisms in the production of the morphine Straub tail reaction and in the potentiation of the morphine Straub tail reaction by amphetamine.     

Schistosoma mansoni: Splenic lymphocyte responses of mice after initial exposure to highly irradiated cercariae

Inbred $\text{C}\text{57}\text{B}\text{1}\text{6}$ and CBA mice were immunized with ⁶⁰Co-irradiated (50 kR) Schistosoma mansoni cercariae. Based on the percentage reduction from controls in the numbers of adult parasites developing from a challenge cercarial exposure, the level of protection among immunized $\text{C}\text{57}\text{B}\text{1}\text{6}$ mice ranged from 56 to 74%, and among immunized CBA mice from 10 to 27%. In a longitudinal study, parallel in vitro comparisons of mitogen- and antigen-stimulated lymphocyte proliferative responses were performed with spleen cells from immunized and control mice of both strains. In contrast to decreased mitogen reactivity during a chronic, patent infection, immunization with irradiated cercariae resulted in no alteration in PHA and LPS responses in the reactivity of either strain. A vigorous antigen-specific reactivity was noted in the responses of immunized CBA mice. Additionally, a biphasic pattern of responsiveness characterized the CBA responses to antigens of cercarial, adult worm, or schistosomal egg origin. In comparison, there was a greatly diminished reactivity in immunized $\text{C}\text{57}\text{B}\text{1}\text{6}$ mice to the same antigens. Therefore, no obvious correlation existed in this model between the relative magnitude of antigen-specific responses between the two strains and the level of anti-schistosome immunity induced.     

The effects of narcotic analgesics and narcotic antagonists on ganglionic transmission in the rat.

The effects of narcotic analgesics, narcotic-antagonist analgesics and narcotic antagonists on ganglionic transmission in the superior cervical ganglia of the rat were studied $\text{in}$$\text{vivo}$ and $\text{in}$$\text{vitro}$. $\text{In}$$\text{vivo}$ administration of morphine, meperidine, methadone, pentazocine or naltrexone blocked ganglionic transmission. Levorphanol, cyclazocine, nalorphine and naloxone had no effect on ganglionic transmission in this procedure. $\text{In}$$\text{vitro}$ studies confirmed the $\text{in}$$\text{vivo}$ results with the exception of levorphanol, cyclazocine and nalorphine, which were also found to block ganglionic transmission $\text{in}$$\text{vitro}$. In both preparations, naloxone did not antagonize the effect of morphine, suggesting that the effects of morphine and the other opiates were nonspecific. Similar potency of $\text{d}$- and $\text{l}$-isomers of pentazocine and cyclazocine support this conclusion. The observation that naltrexone blocked ganglionic transmission, but the other pure narcotic antagonist, naloxone, was inactive is somewhat unique to this test procedure and possibly significant.     

Metabolism and uptake of L-pipecolic acid by brain and heart

Metabolism and uptake of $\text{L}$-[1-¹⁴C]pipecolate was studied in the rat through tail vein injection at low (30 μg/kg) and high (30 mg/kg) doses. No radioactive compound other than $\text{L}$-pipecolate was detected in the brain or heart samples 0.5 to 60 min after injection. The contents of $\text{L}$-pipecolate in the brain dropped rapidly to reach a plateau value 2 min after injection both in the low and high dose experiments (from 0.06 to 0.05 and from 86 to 55 nmole/g brain, respectively). Similar results were observed for the heart except that the heart had $\text{L}$-pipecolate contents 2–3 fold higher than the brain at every time interval. The influx of $\text{L}$-pipecolate to the brain, as measured by the plasma/brain ratio of its contents, was 3 fold lower than the heart at each sampling point throughout the course of measurement for both dosages. The influx of $\text{L}$-pipecolate from the plasma to the heart reached an equilibrium, i.e., plasma/heart = 1, 60 min after injection for both dosages; the plasma to brain ratio was 3 at 60 min. These results indicate that there is a blood-brain transport barrier for $\text{L}$-pipecolate in the rat, which may account for the differences in neuronal effects of $\text{L}$-pipecolate when administered intracerebrally or intraperitoneally.     

The effect of vitamin B12 inhibition in vivo: Impaired folate polyglutamate biosynthesis indicating that 5-methyltetrahydropteroylglutamate is not its usual substrate

Using 5-[¹⁴C] methyltetrahydropteroylglutamate and [³H] pteroylglutamate it was found that vitamin B₁₂ dependent methyltransferase can be inhibited $\text{in vivo}$ in mice by nitrous oxide. Examination of the liver [³H] folates showed as expected that both controls and nitrous oxide treated mice had synthesised the reduced 5-methyl form. However, the controls had converted [³H] almost exclusively into a polyglutamate with virtually no monoglutamate present, while nitrous oxide treated mice had failed to add glutamates to over half of the incorporated folate. Thus $\text{in vivo}$ demethylation may be necessary prior to polyglutamate biosynthesis and act as a method of controlling folate accumulation, or be used to create a concentration gradient with the circulating folate.     

Effects of the intracerebroventricular injection of antinociceptive doses of acetylcholine on the stereospecific binding of 3H-dihydromorphine

The antinociceptive effects of intraventricularly administered acetylcholine (ACh) and its congeners have been demonstrated by previous investigators. The opiate receptor binding concept was used in this study to investigate possible correlations between ACh antinociception and its effects on opiate stereospecific binding. ACh $\text{in vitro}$ decreased the stereospecific binding of ³H-dihydromorphine in mouse brain homogenates. Such decrease was also observed in the brain homogenates of mice which had been treated with ACh intracerebroventricularly (i.v.t.). The decrease in the stereospecific binding of ³H-dihydromorphine induced by (i.v.t.) acetylcholine was inhibited by naloxone, atropine, cyclazocine and pentazocine. The $\text{d}$-isomers of cyclazocine and pentazocine were more potent than the $\text{l}$-isomers in antagonizing the inhibitory effects of i.v.t. acetylcholine upon the stereospecific binding of ³H-dihydromorphine to mouse brain homogenates. The same stereospecificity of these two narcotic analgesics in blocking acetylcholine had been previously observed in the tail-flick test. It is suggested that the antinociceptive effects of acetylcholine are related to the inhibition of opiate stereospecific binding, the mechanism of which is yet to be understood.     

Effects of prolyl-leucyl-glycinamide and cyclo(leucyl-glycine) on morphine-induced antinociception and brain μ, δ and κ opiate receptors

The effects of prolyl-leucyl-glycinamide and cyclo (leucyl-glycine) on morphine-induced antinociception in mice and on $\text{in vitro}$ binding of ³H-ligands for opiate receptor subtypes (μ, δ and κ) the mouse brain homogenate were determined. Subcutaneous administration of either of the above peptides (1, 2, and 4 mg/kg) 10 min prior to the injection of morphine did not affect morphine-induced antinociception as evidenced by the identical ED₅₀ values of morphine in vehicle and peptide treated groups. The binding of ³H-dihydromorphine and ³H-naloxone ( μ receptors), ³HDAla²DLeu⁵-enkephalin (δ receptors), and ³H-ethylketocyclazocine (κ receptors) to opiate receptors in the mouse brain homogenate was also unaffected by both the peptides over a large concentration range. It is concluded that these peptides do not interact with brain opiate receptors.     

Opioid properties of beta-lipotropin fragment 60-65, H-Arg-Try-Gly-Gly-Phe-Met-OH.

The pharmacologic activity of the hexapeptide fragment corresponding to the amino acid fragment 60–65 in β-lipotropin, (β-LPH-(60–65)) was studied $\text{in vitro}$ and $\text{in vivo}$. In binding assays on synaptosomal plasma membrane the peptide was found to be equipotent to met-enkephalin, but behaved differently to cations; in contrast to met-enkephalin both Mn⁺² and Na⁺ enhanced the binding of β-LPH-(60–65) to synaptosomal plasma membrane. On both the quinea pig ileum and mouse vas deferens β-LPH-(60–65) inhibited contractions elicited by electrical stimulation and each effect was reversible by naloxone. On the guinea pig ileum β-LPH-(60–65) was equipotent to met-enkephalin and 0.5 as potent as normorphine but on the vas deferens it was 4.6 times more potent than normorphine. The activities of β-LPH-(60–65) appear to be due to the intact compound rather than to its conversion to met-enkephalin, since the peptide extracted from the ileum assay was found to behave identically as β-LPH-(60–65) with high pressure liquid chromatography. When β-LPH-(60–65) was administered centrally to mice and rats, no overt central actions were observed and an antinociceptive effect could not be demonstrated. Nor did β-LPH-(60–65) antagonize morphine action or precipitate the withdrawal syndrome in morphine dependent animals. It is concluded that the good agreement which generally exists between $\text{in vitro}$ and $\text{in vivo}$ assay procedures for opiate-like activity of morphine and its surrogates does not necessarily hold for the endogenous peptides with similar actions.     

Evidence of possible opiate dependence during the behavioral depressant action of a single dose of morphine

Rats were trained to lever press for food pellets under a 20 response fixed ratio (FR 20) schedule of reinforcement. A single injection of 15 mg morphine SO₄/kg suppressed operant behavior for $\text{1}\text{1}\text{2}\text{–3}\text{1}\text{2}\text{hrs}$, after which time responding resumed at a reduced rate. When 0.25 mg naloxone HCl/kg was given during the recovery phase, the behavioral depressant effect of the narcotic was immediately reversed and operant performance returned to predrug rates. In contrast, when 0.5 mg naloxone/kg was given at this time, operant behavior was abolished for at least 1 hr. Naloxone, at these doses, did not affect responding in drug-naive subjects. These results suggest that a single, relatively low dose of morphine can induce transient dependence which is detectable for several hrs after drug administration, at a time when the acute pharmacological actions of morphine are still apparent.     

Identification of immunogens of Mycoplasmapneumoniae by protein blotting

Proteins of $\text{Mycoplasma}\text{pneumoniae}$ were separated by SDS-polyacrylamide gel electrophoresis and transferred to a nitrocellulose sheet by blotting. Sera obtained from infected hamsters and immunized rabbits were then incubated with the nitrocellulose strips. Proteins which are capable of eliciting antibodies were detected by indirect immunoradioautography using ¹²⁵I-labeled antisera against hamster or rabbit IgG. Antibodies to seven immunogens were demonstrated in the sera of hamsters infected with $\text{M.}\text{pneumoniae}$ by inhalation, while many more proteins were found to be capable of stimulating antibodies in rabbits immunized parenterally with mycoplasmas. This method should prove useful for identifying those components of a microorganism which elicit antibody responses and contribute to the protective state.     

Monoclonal antibodies to yeast catalase T

Hybridoma cell lines secreting antibodies directed against $\text{Saccharomyces cerevisiae}$ catalase T were constructed by fusing spleen cells of mice immunized with catalase T with P3×63Ag8 mouse myeloma cells. Culture supernatants were assayed for specific antibodies by incubation with ³⁵S-labelled yeast extracts, adsorption of the immune complexes to Protein A — carrying $\text{Staphylococus aureus}$ cells and analysis of the adsorbed yeast proteins by sodium dodecylsulfate gel electrophoresis. Two hybrid clones were isolated mediating adsorption of a protein with electrophoretic mobility of catalase T; one of them, showing considerably higher activity, was characterized further. Anti-bodies produced by this clone belong to the IgG class of immuniglobulins; they can be used for immunoadsorption, but not for direct immunoprecipitation and recognize authentic catalase T as well as catalase T apoprotein.     

Decreased phosphorylation of specific proteins in neostriatal membranes from rats after long-term narcotic exposure

The endogenous phosphorylation of membrane-bound proteins was studied in the neostriata of rats treated for three weeks with incrementing doses of morphine. Fractions containing synaptic membranes were incubated with γ-³²P-ATP. Phosphate incorporation into individual proteins was determined by gel-electrophoresis and autoradiography of SDS-solubilized membranes. At short reaction times (10 sec.), phosphorylation of all the endogenous protein substrates was reduced compared to preparations from placebo treated rats, but this decrease was differential. Phosphorylation of the specific protein bands designated F and H (MW 47,000 and 15–20,000) decreased by 60–70% while that of all the other bands decreased by only 15–30%. At longer incubations (2–5 min.) bands F and H remained depressed, while the phosphorylation of all the other bands had reached control values. The bands whose phosphorylation selectively $\text{decreased}$ after long-term narcotic exposure were identified as the proteins whose phosphorylation was reported previously to $\text{increase}$ after training experience. Modifications induced in the phosphorylation of these specific proteins may play a role in the adaptive responses of brain cells to various environmental and pharmacological stimulations.     

Preparation and immunochemical properties of methoxypolyethylene glycol-coupled and N-carboxymethylated derivatives of ragweed pollen allergen, antigen E.

A methoxypolyethylene glycol (PEG)-coupled and several N-carboxymethylated (N-CM) derivatives of antigen E, the major allergenic protein of ragweed pollen, were prepared. The PEG derivative contained seven residues of PEG groups (residue weight about 2100) per molecule of protein and the groups were linked to the lysyl residues of antigen via the 2,6-positions of 4-hydroxy-triazine nucleus. The maximally N-CM derivative contained, respectively, 10, 6, and 2 residues of mono-CM, di-CM, and unmodified lysyl residues per molecule of protein. The CM groups were introduced reductively on reaction with glyoxylic and sodium cyanoborohydride and the extent of mono- and dicarboxymethylation was controlled more by the concentration of cyanoborohydride than by that of glyoxylic acid. The molar allergenic activities of the PEG and the N-CM derivatives in man were, respectively, 0.02 and 0.5 of that of the native antigen. Rabbits immunized with the PEG derivative gave antibody titers about $\text{1}\text{8}$th of those obtained with animals immunized with the native antigen. However, the rabbits preimmunized with the PEG derivative gave a vigorous secondary response on challenge with the native antigen and their titers approached those of rabbits preimmunized with the native antigen. The immunogenicity of the reduced and S-carboxymethylated derivative of antigen E which has the denatured conformation was studied as a control. Rabbits immunized with the S-CM derivative gave antibody titers $\text{1}\text{34}$th of those obtained with animals immunized with the native antigen; on secondary challenge with the native antigen, these rabbits gave antibody titers about $\text{1}\text{6}$th of those of animals preimmunized with the native antigen.     

Inhibition of drug metabolism by chronically administered naltrexone

Naltrexone, a long-acting narcotic antagonist, was administered to mice via aong-term delivery system of 1.5 mm beads containing 2 mg of naltrexone in a 90/10 polylactic/glycolic acid copolymer (Dynatech R/D Comp.). A single bead implanted subcutaneously antagonized the analgesic action of interimittently administered morphine sulfate (20 mg/kg, i.p.) for 25–35 days. During this 4–5 week period during which the naltrexone was pharmacologically active, the activities of the hepatic, microsomal mixed function oxidases aminopyrine N-demethylase and aniline hydroxylase were depressed to 30–50% of the levels seen in sham-implanted controls. Hexobarbital sleeping time and zoxazolamine paralysis time were significantly prolonged, and the blood half-lives of ¹⁴C-pentobarbital and ¹⁴H-amphetamine were lengthened when the monoxygenase activities were inhibited. Sleeping time following administration of ethanol was unaffected. $\text{In}$$\text{vitro}$, both naltrexone and its major metabolite, ß-naltrexol, were found to be inhibitory of the activities of aminopyrine N-demethylase and aniline hydroxylase, although the parent compound was the more potent inhibitor of both activities by a factor of 2–3.     

Differentiation of beta-adrenoceptors in right atrium, diaphragm and adipose tissue of the rat, using stereoisomers of propranolol, alprenolol, nifenalol and practolol.

2-Diazomorphine-bovine serum albumin (2-DAM-BSA) was prepared by diazotizing p-aminobenzoyl-BSA to morphine. Rabbits immunized with 2-DAM-BSA produced antibodies directed to morphine. A 50 percent reduction in ³H-morphine binding required 4.4 pmol of morphine, and 60, 225, and 350 pmol of normorphine, morphine-3-glucuronide, and codeine, respectively. A radioimmunoassay for brain morphine is described, validated, and used to determine if naloxone alters brain morphine in morphine pelleted mice. The apparent biological half-life of morphine in brain was approximately 52 hours between 24 and 72 hours after pellet implantation, and decreased to 1.25 hours after pellet removal. Naloxone (10 mg/kg) administered 24, 48, or 72 hours after implantation and in doses of 1.0–100 mg/kg administered at 48 hours resulted in either no significant change, or, in a few experiments, increased the brain concentration of morphine. The present experiments could not detect a fraction of total brain morphine that is reduced by naloxone.     

Actions of morphine on prostate gland fructose metabolism

Varying doses of morphine sulfate (10, 20 or 40 mg/kg daily × 10) were observed to suppress metabolic activities in the mouse prostate gland. Prostate gland fructose, an index of androgenic activity, was significantly reduced by these dose regimes of morphine (P < 0.01). Injections of morphine sulfate (20 mg/kg daily × 10) led to an inhibitition in the $\text{in vitro}$ synthesis of both fructose^?14C and sorbitol^?14C from glucose^?14C by the prostate gland, part of which may have been due to decreased uptake of glucose by the gland. The $\text{in vitro}$ assimilation of 2-deoxyglucose^?14C by the prostate was also reduced by morphine treatment. The $\text{in vitro}$ actions of morphine (2 × 10^?3M) on the metabolism of radioactive glucose by the mouse prostate gland likewise revealed a significant reduction in the formation of sorbitol^?14C, but no decrease in fructose^?14C formation. These results indicate that both the $\text{in vitro}$ and $\text{in vivo}$ actions of morphine can inhibit fructose metabolism in the prostate gland.