Thermal and PGE2 sensitivity of the organum vasculosum lamina terminalis region and preoptic area in rat brain slices.

Abstract

SUMMARY1. The effects of local applications of prostaglandin E2 (PGE2) on the unit activity of fifty-one neurones in the organum vasculosum lamina terminalis (OVLT) region and fifty-eight neurones in the preoptic area (POA) were investigated in small tissue slices from the rat hypothalamus containing the OVLT and POA isolated from each other.2. Of these, thirty OVLT and twenty-eight POA neurones were warm sensitive and increased their discharge rate in response to a rise in tissue temperature. One OVLT neurone and one POA neurone were cold sensitive and showed the opposite type of responses to changes in temperature. The thermosensitivity of these neurones was still observed in a Ca21 free-high Mg2+ solution.3. Perfusion with PGE2 in doses between 1 and 250 nm changed the discharge rate in forty-two of fifty-one OVLT neurones and in thirty-two of fifty-eight POA neurones in a dose-dependent manner. The responses to PGE2 were not lost during synaptic blockade. The threshold dose of PGE2 to alter the discharge rate of the OVLT neurones (4-8+1-1 (S.E.M.) nM, n = 16) was significantly lower than that of the POA neurones (40 9 + 12 2 nm, n = 16).4. Fifteen of forty-two OVLT neurones exhibited the responses with a slower onset (latency 5-13 min) and a longer duration (20 min to 3 h), but such responses were observed in only one of thirty-two POA neurones.5. The responses of OVLT and POA neurones to PGE2 (50-250 nm) were reversibly blocked by a concurrent application of AH6809. a prostanoid EP, and/or a DP receptor antagonist.6. While there was no clear correlation between the type of thermosensitivity and the type of response to PGE2 among the POA neurones, a significantly higher incidence of inhibitory response to PGE2 was found among the warm-sensitive neurones in the OVLT region.7. The lower threshold responses to PGE2 and the higher incidence of PGE2 responsiveness among OVLT neurones are consistent with previous findings which showed that the highest density of PGE2 receptor binding and the highest pyrogenic sensitivity to microinjected PGE2 were observed in the OVLT region. The results MS 9526

Roles of sympathetic nervous system in the suppression of cytotoxicity of splenic natural killer cells in the rat.

“…Therefore, possible brain sites for the action may be the circumventricular organs such as the organum vasculosum laminate terminalis (OVLT) and median eminence, which lie near the third ventricular system. The OVLT has been suggested to be one of the responsible sites for both the febrile and neuroendocrine responses to intravenous injections of interleukin-lfl (Stitt, 1985;Katsuura, Arimura, Koves & Gottschall, 1990;Matsuda, Hori & Nakashima, 1992). Another possibility is that recombinant human interferon-a may act within the hypothalamus.…”

Mast cells are necessary for the hypothermic response to LPS-induced sepsis

“…If this is the case, imprecise effectors would lead to disruption of normal T c regulation. Finally, firing of warm-and cold-sensitive neurons in the brain mediating autonomic responses required for precise thermoregulation around a set point could be altered by a lack of mast cell mediators (26). In this case, altered processing in thermoregulatory control centers would compromise efferent signals to thermal effectors of T c .…”

Heat Shock and Genetic Activation of HSF-1 Enhance Immunity to Bacteria

“…6 In mammals, where the molecular mechanisms of fever initiation have been very well studied, it is known that endogenous pyrogens stimulate the production of prostaglandins which are the main mediators of increased temperature. [7][8][9][10][11][12][13] Indeed, the extensively used nonsteroidal anti inflammatory drugs reduce fever by targeting prostaglandin synthesis.…”