| 释义 |
presyˈnaptic, a.
1. Cytology. [pre- B. 1.] Prior to meiotic synapsis.
1909Ann. Bot. XXIII. 21 In common with Grégoire ('07), we may adopt, provisionally at least, the following scheme of phases for convenience of clearness in description. The prophases of division naturally fall into two periods, the pre-synaptic and the post-synaptic phases. 1912[see leptotene]. 1921Ann. Bot. XXXV. 367 Fig. 5 represents a presynaptic pollen mother-cell.
2. Physiol. [pre- B 3] Of, pertaining to, or designating a neurone that transmits a nerve impulse across a synapse. Opp. postsynaptic a. 2.
1937Proc. R. Soc. B. CXXII. 113 The response is erratic in that by no means every pre-synaptic stimulus yields a post-synaptic response. 1950[see hyperpolarize v.]. 1965G. H. Bell et al. Textbk. Physiol. & Biochem. (ed. 6) xxxix. 796 In general the presynaptic fibre divides up into numerous fine branches which then end in greatly expanded terminals, presynaptic knobs, which make intimate contact with part of the membrane of the cell body or dendrites of the postsynaptic cell. 1979Internat. Rehabilit. Med. I. 45/1 New evidence of the blocking of pain specific receptors..by morphine-like substances produced by presynaptic dendrites.
Hence presyˈnaptically adv.
1971Nature 12 Nov. 102/1 In the central nervous system, amphetamine releases presynaptically bound NE [sc. norepinephrine] or DA [sc. dopamine] and blocks their re-uptake. 1976Ibid. 3 June 418/1 The fact that chlorpromazine also blocks α-adrenoceptors, possibly presynaptically located, may also contribute to the enhanced presence of catecholamines at the synaptic cleft. |