ABSTRACT
In the rat vas deferens, a vast number of experiments have shown that the alpha-adrenoceptors present are of two types: alpha 1 and alpha 2. This series of experiments with the isolated rat vas deferens was designed to probe by pharmacological means, the nature of the responses elicited by neurogenic transmural stimulation and also those responses evoked by exogenous NE and DA. The methodology required the production of chemical denervation, neurotransmitter depletion, and the use of specific adrenoceptor blockers. The results obtained with the blocking agents, yohimbine or prazosin versus NE and DA, were pA2 values that were virtually interchangeable. The effects of chemical alteration with 6-OH-DA or reserpine point to a certain similarity and interdependence of the mechanism of action for the two neurotransmitters. Therefore, it is suggested that these two transmitters act at the same receptor site or share a common receptive microenvironment in the rat vas deferens.
Subject(s)
Dopamine/pharmacology , Receptors, Adrenergic, alpha/drug effects , Vas Deferens/drug effects , Animals , Dose-Response Relationship, Drug , In Vitro Techniques , Male , Muscle Contraction/drug effects , Norepinephrine/pharmacology , Prazosin/pharmacology , Rats , Rats, Inbred Strains , Yohimbine/pharmacologyABSTRACT
1. The effects of haloperidol on the responses of the isolated rat vasa deferentia to catecholamines and ACh were studied. 2. Haloperidol produced a competitive antagonism to responses elicited by NA and DA in the vas deferens. 3. The M1 and M2 muscarinic responses to ACh of the vas deferens were potentiated by this neuroleptic. 4. The AChE activity of the vas deferens was significantly depressed by pretreatment with haloperidol. 5. The ability of haloperidol to lower AChE activity was compared with that of neostigmine and it may be due to a similar molecular mechanism. 6. The present results suggest that haloperidol has anti-AChE properties that may be responsible for the potentiation of the responses to ACh. 7. The study indicates that haloperidol has a wider range of pharmacological actions than previously reported.
Subject(s)
Haloperidol/pharmacology , Muscle, Smooth/metabolism , Neurotransmitter Agents/metabolism , Acetylcholinesterase/metabolism , Animals , Catecholamines/metabolism , In Vitro Techniques , Male , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Muscle, Smooth/enzymology , Neostigmine/pharmacology , Rats , Rats, Inbred Strains , Vas Deferens/drug effects , Vas Deferens/enzymology , Vas Deferens/metabolismABSTRACT
Changes in the activity of acetylcholinesterase (AChE) of the isolated vas deferens from normal, castrated, morphine and ethanol-tolerant rats were studied. Three days after the termination of treatment with morphine and on the last day of treatment with ethanol, a significant inhibition of the activity of AChE was detected. This reduction in the enzymatic activity persisted in morphine-tolerant rats for 15 days, but not for 30 days, at which time the levels of AChE were determined to be normal. However, in ethanol-tolerant rats, there were no significant changes found at days 15 or 30. The activity of AChE was decreased significantly in castrated rats, but this effect was reversed by treatment with testosterone. During withdrawal from morphine or ethanol, the levels of AChE were significantly increased. The results indicate that morphine and ethanol may be inducing changes in the feedback mechanism which regulates the levels of AChE at post-synaptic sites, and these changes could play an important role in the development of tolerance to morphine and to ethanol.
Subject(s)
Acetylcholinesterase/metabolism , Muscle, Smooth/enzymology , Orchiectomy , Animals , Drug Tolerance , In Vitro Techniques , Male , Morphine/pharmacology , Muscle, Smooth/drug effects , Rats , Rats, Inbred Strains , Substance Withdrawal Syndrome/physiopathology , Testosterone/pharmacologyABSTRACT
1. The effects of hemicholinium (HC-3) on several autonomic agents in the isolated rat vas deferens were investigated. 2. HC-3 reduced slightly the effects of NE and DA. 3. The responses by cholinergic agents on the M1-ACh receptors were not modified, however HC-3 reduced, significantly, the responses on the M2-ACh receptors. 4. These results suggest that HC-3 besides its anticholinergic properties possesses ability to interact with adrenoceptors in the isolated rat vas deferens.
Subject(s)
Autonomic Agents/pharmacology , Hemicholinium 3/pharmacology , Muscle, Smooth/metabolism , Receptors, Adrenergic/drug effects , Receptors, Cholinergic/drug effects , Animals , Dopamine/pharmacology , Electric Stimulation , In Vitro Techniques , Male , Muscle, Smooth/drug effects , Muscle, Smooth/physiology , Norepinephrine/pharmacology , Parasympathomimetics/pharmacology , Rats , Rats, Inbred StrainsABSTRACT
The study was undertaken to obtain some information about the development of the autonomic receptors and the AChE activity in the rat vas deferens. The results suggest that the adrenoceptors were fully developed at birth. The M1-ACh receptors were developed before the M2-ACh receptors. The AChE activity developed before the ACh muscarinic receptors of the rat vas deferens.
