Expression of muscarinic acetylcholine receptors (M1-, M2-, M3- and M4-type) in the neuromuscular junction of the newborn and adult rat.
Using intracellular recording and immunohistochemistry, we studied the presynaptic muscarinic autoreceptor subtypes controlling ACh release in the neuromuscular junctions of the newborn (3-6 days postnatal) and adult (30-40 days) rat. In the Levator auris longus muscles of both newborn and adult rats, acetylcholine release was modified by the M1-receptor selective antagonists pirenzepine (10 microM) and MT-7 (100 nM) and by the M2-receptor selective antagonists methoctramine (1 microM) and AF-DX 116 (10 microM). The M4-receptor selective antagonists tropicamide (1 microM) and MT-3 (100 nM) can also modify the neurotransmitter release in certain synapses of the newborn muscles. The neurotransmitter release was not altered by the M3-receptor selective antagonist 4-DAMP (1 microM) in the adult or newborn rats. However, we directly demonstrate by immunocytochemistry the presence of these receptors in the motor endplates and conclude that M1-, M2-, M3- and M4-type muscarinic receptors are present in all the neuromuscular junctions of the rat muscle both in newborn and adult animals. These receptors may be located in the perisynaptic glial cell as well as at the nerve terminals.
Garcia
N
N
Histology and Neurobiology Unit, Faculty of Medicine and Health Sciences, Rovira i Virgili University, carrer St Llorenç num. 21, 43201 Reus, Spain.
Santafé
M M
MM
Salon
I
I
Lanuza
M A
MA
Tomàs
J
J
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D003959:Diamines / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation / Q000378:metabolism; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism*; D010890:Pirenzepine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043643:Receptor, Muscarinic M1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D043585:Receptor, Muscarinic M2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D043587:Receptor, Muscarinic M3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D043588:Receptor, Muscarinic M4 / Q000037:antagonists & inhibitors / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism*; D014331:Tropicamide / Q000494:pharmacology
D003959:Diamines; D018727:Muscarinic Antagonists; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D043588:Receptor, Muscarinic M4; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D014331:Tropicamide; C054938:methoctramine