ABSTRACT
Extracellularly recorded firing rates of neurons in slices of the preoptic area and anterior hypothalamus (PO/AH) of the rat were determined during thermal stimulation. Human recombinant interleukin-1beta (20 ng/ml) did not influence temperature-insensitive neurons, but reduced the firing rate and thermosensitivity in linear warm-sensitive neurons, and shifted the thermal thresholds of activation in threshold warm- and cold-sensitive neurons by 1.1-2.3 degrees C to hyperthermic temperatures. The data support the suggestion that endogenous pyrogens may act on different populations of thermosensitive PO/AH neurons to induce fever. The shift of the thermal thresholds of activation of threshold warm- and cold-sensitive neurons in combination with the otherwise maintained temperature sensitivity of these neurons appears to play a major part for the controlled shift of body temperature and the maintenance of the elevated body temperature during cytokine-induced fever.
Subject(s)
Body Temperature Regulation/physiology , Fever/metabolism , Hypothalamus, Anterior/metabolism , Interleukin-1/metabolism , Neurons/metabolism , Preoptic Area/metabolism , Animals , Cold Temperature , Fever/etiology , Hot Temperature , Hypothalamus, Anterior/cytology , Hypothalamus, Anterior/drug effects , In Vitro Techniques , Interleukin-1/pharmacology , Male , Membrane Potentials/drug effects , Membrane Potentials/physiology , Neurons/cytology , Neurons/drug effects , Preoptic Area/cytology , Preoptic Area/drug effects , Rats , Rats, Wistar , Sensory Thresholds/drug effects , Sensory Thresholds/physiologyABSTRACT
The role of the celiac plexus in maintaining temperature homeostasis in rats during cold stress was studied histochemically, ultrastructurally, and electrophysiologically. Inhibition on efferent impulses in preganglionic (splanchnic) nerves and facilitation in postganglionic (superior mesenteric) nerves during a short-term cold exposure leading to slight hypothermia were found. In cold-exposed animals after the celiac plexus decentralization, the neurons showed an increase in the fluorescence intensity and activity of energy metabolism enzymes, hyperplasia of fine structures responsible for protein synthesis and energy supply of cells. It is suggested that during cold stress when efferent impulse flow in preganglionic nerves markedly decreases, the celiac plexus becomes a regulatory centre for autonomic functions involved in the maintenance of temperature homeostasis.
