No abstract

Due to errors on the part of the typesetter, the article was published with incorrect versions of the column heads of Table 1 and the illustration and legend of Fig. 2. The correct table and figure are given in full here.

1 The effects of 5-HTlA antagonists on guinea-pig behaviour and dorsal raphe neuronal activity were investigated. 2 WAY100135 (10 mg kg-', s.c.) and WAY100635 (1 mg kg-', s.c.) significantly reduced the behaviours induced by 8-hydroxy-2-(di-n-propylamino) tetralin (8-OHDPAT) (1 mg kg-', s.c.) indicative of post-synaptic 5-HTIA receptor antagonism. WAY100635 (10 mg kg-', s.c.) alone induced ear twitches, which were antagonized by ketanserin (1 mg kg-', s.c.), but no other overt behaviours. 3 WAY100635 (0.125 mg kg-', i.v.) produced a right-ward shift in the dose-related inhibition of neuronal firing by 8-OHDPAT (5-100 pug kg-', i.v.) but did not affect the maximum inhibition induced by 8-OHDPAT indicating competitive antagonism between 8-OHDPAT and WAY100635 at the 5-HTIA somato-dendritic autoreceptor in the dorsal raphe nucleus of the guinea-pig. WAY100635 also produced a dose-related increase in the basal firing of 5-HT neurones in the dorsal raphe nucleus and restored the firing of dorsal raphe neurones previously inhibited by 8-OHDPAT (10 Yg kg-', i.v.). 4The results indicate that WAY100635 is a competitive 5-HTIA antagonist in the guinea-pig. Furthermore WAY100635 can increase 5-HT neuronal firing, suggesting that it blocks a 5-HTIA receptor-mediated inhibitory tone acting on guinea-pig 5-HT neurones resulting in increased 5-HT release and 5-HT2 receptor-mediated behaviours.

This study confirms that in patients with established osteoporosis, there is also a distinct group with a low vitamin D and a blunted PTH level and that Mg deficiency (as measured by the Mg loading test) is an important contributing factor.