Long-term restoration of deficits in bone mineral density is inadequate in premenopausal women with prior menstrual irregularity

OBJECTIVE

To investigate change in bone mineral density (BMD) in premenopausal women (age, 29-46 years), some of whom were marathon runners with a history of menstrual irregularity.

DESIGN

Longitudinal follow-up.

SETTING

University medical school.

PARTICIPANTS

We investigated 8 sedentary controls (SC) and 19 marathon runners (12 with regular menses (R) and 7 with a history of irregularity (OA) 11.7 +/- 7.9 years before follow-up).

MAIN OUTCOME MEASURES

BMD (g/cm2) of lumbar spine (LS) and proximal femur were determined at baseline and follow-up (3-5 years later). We calculated a menstrual history index (MHI) (estimated periods/year since age 13).

RESULTS

Body mass, age at menarche, and femoral BMD were not statistically different. Follow-up LS BMD (g/cm2) was lower (p < 0.01) in OA (0.936 +/- 0.060) than in R (1.043 +/- 0.103) and SC (1.094 +/- 0.077), even when covarying for age or both age and mass. No group changed BMD significantly with time. Current MHI was lower (p < 0.001) in OA (9.7 +/- 1.4) than in R (11.3 +/- 0.5) and SC (11.8 +/- 0.4). MHI for the teenage years was lower in OA than in SC but not in R. OA had significantly lower MHI than did R and SC for the third and fourth decades. Only MHI during the third decade correlated significantly with LS BMD for all subjects.

CONCLUSIONS

Restoration of LS BMD deficit in women with prior menstrual irregularity aged over 30 is slow and may never reach the same level as age-related controls; secondly, this may be the result of both bone loss in the third decade of life and reduced acquisition during adolescence.

Regional effects of neurotensin on the electrically stimulated release of [3H]dopamine and [14C]acetylcholine in the rat nucleus accumbens

This study has shown that neurotensin (NT) increases the electrically stimulated release of [3H]DA to a similar extent in all but the extreme caudolateral area of the rat nucleus accumbens and appears to modulate DA release equally in the medial and lateral zones of this brain area. The simultaneous release of ACh was not significantly affected by NT.

Effect of amygdaloid kindling on [3H]dopamine and [14C]acetylcholine release from rat prefrontal cortex and striatal slices

The involvement of the dopaminergic (DA) systems in the control of limbic kindled seizures is ill defined. The effects of kindling on DA activity may have been overlooked in the past, because of its subtle unilateral occurrence and/or the variance of the endogenous imbalance of DA activity in normal animals. In the present study rats were screened for their endogenous DA imbalance using amphetamine-induced rotational behaviour. Electrical or sham kindling was applied in the hemisphere with the higher endogenous DA activity. Sections of the bilateral prefrontal cortex and dorsal and ventral striatum were dissected either 2 hours or 21 days after the final seizure and the electrically stimulated release of [3H]DA and [14C]acetylcholine (ACh) determined. Release was also measured in the presence of quinpirole or sulpiride to assess the activity of pre- and postsynaptic DA D2-receptors. Long-term effects of kindling consisted of facilitation of ACh release in the ventral striatum contralateral to the kindled amygdala and bilateral depression of DA release in the prefrontal cortex. Kindling therefore produced area specific changes in neurotransmitter systems giving rise to increased pro-convulsive cholinergic activity in the ventral striatum and decreased anti-convulsive dopaminergic activity in the prefrontal cortex.

Evidence that the stimulatory effect of neurotensin on dopamine release in rat nucleus accumbens slices is independent of dopamine D2-receptor activation

Neurotensin (NT, 10(-9) M and 10(-7) M) increased the electrically stimulated release of [3H]dopamine (DA) in rat nucleus accumbens slices. This effect was not altered by activation of DA D2-receptors with high or low concentrations of quinpirole (10(-6) M and 10(-8) M) or blockade of DA D2-receptors with near maximal concentrations of sulpiride (10(-6) M and 10(-5) M). The sulpiride-mediated increase in [3H]DA release and the release induced by NT were additive. These results suggest that NT functions independently of DA D2-receptor activation to modulate DA release in the nucleus accumbens. NT did not modulate the simultaneous release of [14C]acetylcholine.

Lack of effect of chronic desipramine treatment on dopaminergic activity in the nucleus accumbens of the rat

The binding of [3H]SCH 23390 to dopamine (DA) D1-receptors was measured in the nucleus accumbens of rats treated chronically with desipramine for 14 days. DA D1- and D2-receptor binding using [3H]SCH 23390 and [3H]spiperone, respectively as ligands, was determined in rats treated for 28 days. Neither Bmax nor Kd values were influenced by chronic desipramine treatment. In addition, chronic desipramine treatment (28 days) did not influence the dose dependent, quinpirole (10-1000 nM)-mediated inhibition of the electrically stimulated release of [3H]DA release and [14C]ACh from nucleus accumbens slices or the dose dependent increase in [3H]DA release and decrease in [14C]ACh release in the presence of 1 and 10 microM nomifensine. Therefore, our results suggest that the effect of chronic antidepressant treatment cannot be attributed to changes in either DA D1- or D2-receptor binding or DA D2-receptor function in the nucleus accumbens.

The modulatory effect of neurotensin on [3H]dopamine release from rat nucleus accumbens slices is enhanced after chronic desipramine treatment

In the presence of the reuptake blocker, nomifensine (1 microM), neurotensin caused a dose-dependent increase in the 25 mM K+-evoked release of [3H]dopamine ([3H]-DA) from rat nucleus accumbens slices. Chronic desipramine (DMI)-treatment (20 mg DMI/kg/day, orally for 28 days) caused a significant reduction in the K+-stimulated release of [3H]DA from rat nucleus accumbens slices. This could possibly have resulted from increased DA autoreceptor-mediated inhibition of DA release. Superfusion of the DMI-treated rat tissue with buffer-containing neurotensin (100 nM) resulted in an increase in the K+-evoked release of [3H]DA to a level which was higher than that observed with tissue obtained from untreated rats. A similar enhanced effect of neurotensin on DA release was observed when the DA agonist, apomorphine (APO), and ascorbate were included in the superfusion buffer. These findings are consistent with DMI treatment giving rise to impaired DA release possibly due to DA autoreceptor-mediated inhibition of DA release and cancellation of this effect by neurotensin.