A functional medial preoptic nucleus (MPO) is required for scrotal thermal stimuli to alter the neuronal activity of thermoresponsive ventromedial hypothalamic (VMH) neurons.


Journal Article

Thermoresponsiveness of ventromedial hypothalamic (VMH) neurons to scrotal thermal stimulation was determined before and after microinjection of lidocaine into the medial preoptic nucleus (MPO). Male, urethane anesthetized Sprague-Dawley rats, maintained colonically at 37 degrees C had VMH extracellular neuronal activity recorded following 3 cycles of scrotal thermal stimulation (localized, incremental heating and cooling, between 10 and 40 degrees C). Based on their thermal coefficients (TC), warm (WRN), cold (CRN) thermoresponsive and temperature non-responsive (TNRN) VMH neurons had their neuronal activity recorded following each cycle of scrotal thermal stimulation before and after MPO injections of sterile saline (300 nl volume) or 2% buffered lidocaine (200 ng). Thermoresponsiveness of all warm and cold VMH neurons to scrotal thermal stimulation was blocked by prior lidocaine administration into the MPO, effects that were reversed approximately 60 min after. However, MPO lidocaine administration caused no significant change in the thermal coefficients of VMH TNRNs to scrotal thermal stimulation. Results infer that a functional MPO is required for thermal afferent signals arising from the scrotum to reach thermoresponsive VMH neurons.

Full Text

Cited Authors

  • Li, Q; Thornhill, J

Published Date

  • April 1996

Published In

Volume / Issue

  • 716 / 1-2

Start / End Page

  • 134 - 140

PubMed ID

  • 8738229

Pubmed Central ID

  • 8738229

Electronic International Standard Serial Number (EISSN)

  • 1872-6240

International Standard Serial Number (ISSN)

  • 0006-8993

Digital Object Identifier (DOI)

  • 10.1016/0006-8993(96)00039-x


  • eng