1. Responses of anterior hypothalamic-preoptic thermosensitive neurons to thyrotropin releasing hormone and cyclo(his-pro)
- Author
-
Hisao Koga, Toshikazu Kiyohara, Mari Yamasaki, Toyoko Asami, and Tetsuro Hori
- Subjects
Male ,endocrine system ,medicine.medical_specialty ,Central nervous system ,Thyrotropin-releasing hormone ,Peptide hormone ,Biology ,Peptides, Cyclic ,Piperazines ,Norepinephrine ,Cellular and Molecular Neuroscience ,Diencephalon ,chemistry.chemical_compound ,Internal medicine ,medicine ,Animals ,Neurotransmitter ,Thyrotropin-Releasing Hormone ,Neurons ,Pharmacology ,Temperature ,Rats, Inbred Strains ,Thermoregulation ,Preoptic Area ,Rats ,Electrophysiology ,Endocrinology ,medicine.anatomical_structure ,Hypothalamus, Anterior ,nervous system ,chemistry ,Hypothalamus ,hormones, hormone substitutes, and hormone antagonists - Abstract
Effects of local application of thyrotropin releasing hormone (TRH) and its metabolite, histidyl-proline diketopiperazine [cyclo (His-Pro)], on the activity of thermosensitive and thermallyinsensitive neurons of the anterior hypothalamic-preoptic area were investigated in urethane-anesthetized rats. Microelectrophoretic application of TRH changed the activity of 126 of 206 neurons tested. Thyrotropin releasing hormone predominantly decreased the activity of warm-sensitive neurons and increased the activity of cold-sensitive neurons. Since it has been generally assumed that warm-sensitive and cold-sensitive neurons in the anterior hypothalamic-preoptic area mediate heat and cold defence responses, respectively, the present results are consistent with previous findings showing hyperthermia after injection of TRH into the hypothalamus in the rat. Cyclo (His-Pro) affected the activity of 59 of 153 neurons tested. In addition, cyclo (His-Pro) did not preferentially affect warm- or cold-sensitive neurons. These results indicate that the previously-determined hypothermie effect of cyclo (His-Pro) cannot be explained by its effects on thermosensitive neurons in the anterior hypothalamic-preoptic area.
- Published
- 1988