NEURONAL REGENERATION AND ESTROUS-CYCLE RESTORATION AFTER LOCUS COERULEUS-PERIVENTRICULAR GRAY SUBSTANCE SECTION

The locus coeruleus (LC) was anatomically separated from the periventr icular gray substance (PVG) by means of knife cuts in the adult female rat presenting regular estrous cycling. This resulted in a transient suppression of the estrous cycling that lasted 10-13 days after surger y, After this period, irregular or regular cycling activity was observ ed. The regular cycling was restored 30-45 days after the knife cuts. Golgi impregnation of some of the brains of these rats revealed regene rative elements in the knife-cut-insulted area. Thus, blood vessels, m acrophagic-like elements, and glial-like elements were observed in clo se relation with the knife-cut pathway. Additionally, well-defined sta ined neurons typical of the LC and PVG were observed in close proximit y to the knife-cut pathway. Dendritic and axon projections towards the insulted area were observed. Well defined axons were seen across the knife-cut pathway. These data support, first, that the LC-PVG communic ation is part of a circuitry for the modulation of gonadotropic activi ty, and second, that in the restoration of the estrous cyclicity after the knife cut, regenerative processes leading to a LC-PVG functional reconnection occurred after the knife cut.