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WAY‐100635 antagonist‐induced plasticity of 5‐HT 1A receptors: regulatory differences between a stable cell line and an in vivo native system
Author(s) -
Khawaja Xavier Z.,
Smith Deborah L.,
Nawoschik Stanley P.,
Zhang Jean,
Dunlop John,
Dilks Daniel W.,
Olsen Michael,
Schechter Lee E.
Publication year - 2006
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.03883.x
Subject(s) - receptor , 5 ht receptor , internalization , chinese hamster ovary cell , pertussis toxin , endocrinology , medicine , receptor antagonist , biology , forskolin , chemistry , antagonist , serotonin , biochemistry , g protein
We present evidence that the 5‐hydroxytryptamine 1A (5‐HT 1A ) receptor antagonist, N ‐{2‐[4‐(2‐methoxyphenyl)‐1‐piperazinyl]‐ethyl}‐ N ‐(2‐pyridinyl)cyclohexanecarboxamide (WAY‐100635), can induce receptor internalization in a human (h)5‐HT 1A receptor Chinese hamster ovary (CHO‐K1) cell system. Exposure of h5‐HT 1A CHO cells to WAY‐100635 decreased the cell‐surface h5‐HT 1A receptor density in a way that was both time (24–72 h) and concentration (1–100 n m ) dependent.[ 3 H]WAY‐100635 and [ 3 H]8‐hydroxy‐dipropylaminotetralin ([ 3 H]8‐OH‐DPAT) saturation analyses demonstrated a significant reduction (50–60%) in total h5‐HT 1A receptor number in the WAY‐100635‐treated (100 n m ; 72 h) compared with control cells. In WAY‐100635‐treated cells, the 8‐OH‐DPAT‐mediated inhibition of forskolin (FSK)‐stimulated cAMP accumulation was right‐shifted and the maximal inhibitory response of 8‐OH‐DPAT was impaired compared with control cells. Similar results were obtained for 8‐OH‐DPAT‐mediated Ca 2+ mobilization after WAY‐100635 treatment. h5‐HT 1A receptors labeled with [ 3 H]WAY‐100635, as well as [ 3 H]4‐(2′‐Methoxy)‐phenyl‐1‐[2′‐( N ‐2′′‐pyridinyl)‐p‐fluorobenzamido]ethyl‐piperazine (MPPF), exhibited a time‐dependent rate of cellular internalization that was blocked by endocytotic suppressors and was pertussis‐toxin insensitive. In contrast, quantitative autoradiographic studies demonstrated that chronic treatment of rats with WAY‐100635 for two weeks produced a region‐specific increase in the 5‐HT 1A receptor density. In conclusion, prolonged exposure of an h5‐HT 1A cell‐based system to the 5‐HT 1A antagonist, WAY‐100635, induced a paradoxical internalization of cell surface receptor resulting in depressed functional activity. This suggests that an antagonist can influence 5‐HT 1A receptor recycling in vitro differently to in vivo regulatory conditions.