Effect of morphine and leucine-enkephalin on the electrophysiological responses of Pacinian corpuscles of the cat.

The effects of morphine and Leu-enkephalin on the electrical activity of Pacinian corpuscles isolated from cat mesentery were studied. These drugs caused a short-term increase and subsequent decrease of the impulse activity, accompanied by a monotonic growth of the threshold for firing of action potentials and amplitudes of generator and action potentials. Naloxone induced an effect similar to that of morphine. The results obtained indicate that morphine and Leu-enkephalin evoke an increase in membrane potential of a nerve ending. These data may form the basis of the modulating effect of opioid peptides on encapsulated mechanoreceptor activity.

[Cholinesterase activity in the Pacinian corpuscles in denervation and the application of colchicine to the nerve]. / Aktivnost' kholinesteraz tel'tsakh Pachini pri ikh denervatsii i applikatsii kolkhitsina na nerv.

In the Pacinian corpuscles, cholinesterase activity was predominantly revealed along the plasma membrane and in the cytoplasm of the inner core cells. A faint quantity of histochemical end product was detected in the axis cylinder. An increased cholinesterase activity was found after the nerve transection. This change coincides in time with phagocytosis of degenerated axis cylinder by the inner core cells. A decrease in cholinesterase activity was observed in the Pacinian corpuscles after colchicine application to the nerve. This effect may be due to either the blockade of axoplasmic transport of cholinesterase in afferent nerve or/and to the elimination of the trophic influence exerted by the nerve on the cholinesterase activity in the inner care cells.

[Analysis of the modulating effect of catecholamines on electrogenesis in an isolated mechanoreceptor]. / Analiz moduliruiushchego vliianiia katekholaminov na élektrogenez v izolirovannom mekhanoretseptore.

Superfusion of the isolated Pacinian corpuscles from cat mesenterium with solutions containing dibutyril-cAMP or theophylline caused an increase in spike activity and a decrease in receptor potential amplitude and firing potential threshold. An opposite effect was observed after catecholamine application. It was suggested that the effect of catecholamines on the Pacinian corpuscles is accompanied by a decrease in the cAMP level in a sensory nerve terminal. Norepinephrine decreased the adenylate cyclase activity and activated Na+, K+-ATPase in homogenates of Pacinian corpuscles. The effect of norepinephrine on Na+, K+-ATPase could be eliminated by phentolamine and was not sensitive to propranolol. A possible participation of alpha-adrenoreceptors in modulating catecholamine effect on electrical activity of the Pacinian corpuscles is discussed.

[Localization of the lamellated corpuscle neurons of the cat large intestine mesentery]. / Lokalizatsiia neironov plastinchatykh telets bryzheiki tolstoi kishki koshki.

Electrical activity and ultrastructure of lamellated corpuscles (Pacinian corpuscles) of the cat large intestine mesentery were studied 10 days after uni- and bilateral extirpation of the lumbar spinal ganglia. Terminal degenerated in all the receptors, and there were no electrical reactions at bilateral extripation of ganglia L3-L4, they were preserved in some receptors at bilateral extirpation of ganglia L2-L3 and L4-L5 and at unilateral extirpation of ganglia L3-L4. Structure of the receptors and electrical reactions were preserved in all the lamellated corpuscles at bilateral extirpation at the level of L1-L2 and L5-L6. After enucleation of the corpuscles from the large intestine mesentery, in some neurons of ganglia L3-L4, chromatolysis was observed. After the caudal mesenteric nerve was sectioned, there were no electrical reactions in the lamellated corpuscles of the large intestine mesentery. Hence, the sensitive neurons-theri peripheral processes participate in the formation of the lamellated corpuscles of the cat large intestine mesentery-are situated in the lumbar ganglia L3 and L4.

[Study of individual Pacinian corpuscle mechanoreceptors following application of colchicine to a nerve]. / Izuchenie odinochnykh mekhanoretseptorov telets Pachini pri applikatsii kolkhitsina na nerv.

Colchicine application to the cat caudal mesenteric nerve containing sensory fibers for single mechanoreceptors (Pacinian corpuscles) causes degeneration of the axis cast of the nerve endings. Ultrastructural changes in the receptors showed no difference from the axonal degeneration after the nerve section but the rate of degeneration was considerably slower. Ultrastructural, electrophysiological, and biochemical changes occurring in the Pacinian corpuscles were not the result of direct action of colchicine, but appeared to be realized through the nerve by the axoplasmic transport block. It is suggested that the receptor's structure is under the sensory neuron neurotrophic control.