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Locus ceruleus lesions block pulsatile LH release in ovariectomized rats
J A Anselmo-Franci1, V M Rocha-Barros, C R Franci
1Department of Physiology, Faculty of Dentistry of Ribeirao, Preto, USP, Brazil.
Brain Research
|June 22, 1999
Summary
Lesions in the locus ceruleus (LC) significantly disrupt pulsatile luteinizing hormone (LH) secretion in ovariectomized rats by reducing both the frequency and amplitude of LH pulses. This highlights the LC
Area of Science:
- Neuroendocrinology
- Reproductive Biology
Background:
- Luteinizing hormone (LH) secretion is pulsatile, regulated by gonadotropin-releasing hormone (GnRH) pulses.
- Norepinephrine (NE) from the locus ceruleus (LC) is implicated in GnRH regulation.
- Previous studies showed LC lesions affect LH surges and basal LH levels.
Purpose of the Study:
- To investigate the effect of locus ceruleus (LC) lesions on pulsatile LH secretion in ovariectomized (OVX) rats.
Main Methods:
- LC lesions were induced in OVX rats.
- Blood samples were collected every 5 minutes for 90 minutes from conscious, freely moving rats.
- Plasma LH concentrations were measured using radioimmunoassay.
Main Results:
- LC lesions significantly suppressed pulsatile LH secretion, decreasing both pulse frequency and amplitude.
- Basal and total LH secretion were also reduced following LC lesions.
- These effects were observed only when at least 50% of the LC was destroyed.
Conclusions:
- The locus ceruleus (LC) plays a crucial role in regulating pulsatile LH secretion in OVX rats.
- Reduced NE release in specific brain areas due to LC lesions likely inhibits GnRH and subsequently LH pulsatility.
- These findings elucidate a key neural pathway controlling reproductive hormone secretion.