Toyoko Asami

Effects of interleukin-1 and arachiodonate on the preoptic and anterior hypothalamic neurons

Effects of microelectrophoretic application of ultrapure human interleukin-1 (IL-1), an endogenous pyrogen, on the activity of 80 neurons in the preoptic and anterior hypothalamus (PO/AH) were investigated in the urethane anesthetized rat. IL-1 predominantly decreased the activity of warm-sensitive neurons (15 of 19) and increased the activity of cold-sensitive neurons (10 of 12), but had no effect on 37 of 49 thermally insensitive neurons. The neuronal responses to IL-1 were blocked or attenuated by concurrent application of mepacrine (a phospholipase inhibitor) or sodium salicylate (a cyclooxygenase inhibitor). Local application of sodium arachidonate decreased the activity in 17 of 28 warm-units and excited 12 of 16 cold-units, and the effects of arachidonate were blocked by sodium salicylate. The results are compatible with the view that one or more cyclooxygenase metabolites of arachidonic acid are involved in the IL-1 induced fever.

An evaluation of neurobehavioural problems as perceived by family members and levels of family stress 1–3 years following traumatic brain injury in Japan

Objective: To ascertain the proportion of patients with traumatic brain injury (TBI) admitted to a Japanese district hospital and to evaluate the levels of stress and anxiety in families living with those TBI patients. Design: A retrospective study of patients admitted to hospital from April 1995 to March 1997 and a questionnaire study of family members of survivors. Setting and subjects: All patients referred or transferred to the Emergency Department at the Saga Medical School Hospital, Japan with a primary diagnosis of TBI were studied. Family members living with TBI patients were sent questionnaires. Main outcome measures: The Barthel Index, the Patient Competency Rating Scale, the modified Caregiver Strain Index and the Hospital Anxiety and Depression Scale. Results: There were 34 patients who required hospitalization for care relating to TBI. Of these, nine family members took part in the questionnaire study. Three carers reported fairly high levels of stress and another three carers were considered to be at risk of anxiety and depression. There was a tendency for family members who reported that patients had difficulties in performing behavioural tasks to have higher levels of stress themselves. Conclusion: These preliminary results showed that family members experienced certain levels of stress and were also at risk of anxiety and depression. The impact of TBI on families as well as patients should receive more attention.

Responses of anterior hypothalamic-preoptic thermosensitive neurons to thyrotropin releasing hormone and cyclo(his-pro)

Effects of local application of thyrotropin releasing hormone (TRH) and its metabolite, histidyl-proline diketopiperazine [cyclo (His-Pro)], on the activity of thermosensitive and thermally-insensitive 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 hypothermic effect of cyclo (His-Pro) cannot be explained by its effects on thermosensitive neurons in the anterior hypothalamic-preoptic area.

Thermally-induced activities of the mesencephalic reticulospinal and rubrospinal neurons in the rat

Unit activities of 226 midbrain reticulospinal (mRfS) and non-mRfS neurons and 238 rubrospinal (RbS) and non-RbS neurons were investigated during changes in temperatures of midbrain (Tmb), preoptic and anterior hypothalamus (Thyp) and skin (Ts) in the urethane-anesthetized rat. Responsiveness to Tmb, Thyp and Ts were found in 43.5%, 41.6% and 51.5% of neurons of midbrain reticular formation (mRf), and in 35.2%, 32.7% and 17.6% of neurons of red nucleus (Rb). Higher incidence of responsiveness to remote temperatures was found among Tmb responsive neurons than Tmb unresponsive neurons in both mRf and Rb. The mRf contains significantly greater numbers of neurons having such multiple thermal responsiveness and also of neurons which were activated by falls in temperatures (cold-responsive neurons) than the Rb. These characteristics were more conspicuously seen among mRfS neurons, showing a high degree of convergence of cold signals from different sites of body. On the other hand, RbS neurons did not differ from non-RbS neurons regarding thermal characteristics and showed no particular combinations of responsiveness to temperatures of different sites. Microinjection of procaine and glutamate into the mRf just dorsolateral to the Rb, but not into the Rb, decreased and increased cold-induced increase in EMG activity and shivering without changes in cardiovascular and respiratory parameters and pilomotor activity. The results suggest that mRfS neurons are involved in the control of thermoregulatory muscle tone and shivering.

New concept of spinal orthosis for weakened back muscles

An anterior bending posture of the trunk during walking is often seen among the elderly commonly due to weakened thoraco-lumbar and gluteal muscles. For the management of this debilitating condition, the authors have developed a modified design of thoraco-lumbosacral orthosis (TLSO). Incorporated in this device are pockets for the accommodation of lead weights, which are located posteriorly at the level of the lumbar region and an elasticated anterior abdominal band. The results and level of patient acceptance achieved with the use of this brace have both been excellent.

Responses of anterior hypothalamic-preoptic thermosensitive neurons to substance P and capsaicin

The effects of capsaicin and substance P, applied locally, on the activity of thermosensitive and thermally-insensitive neurons in the anterior hypothalamic-preoptic area were studied with the use of multibarrelled microelectrodes in the urethane-anesthetized rat. In a total of 34 thermosensitive neurons (21 warm-units and 13 cold-units) in the anterior hypothalamic-preoptic area, only 7 units responded to substance P and 27 units (79.4%) were not affected. In contrast, 23 of 57 (40.4%) thermally-insensitive neurons responded to substance P. Of 74 thermosensitive and thermally-insensitive neurons tested with both substance P and capsaicin, only 7 units (9.5%) showed the same direction of change in activity in response to the application of both drugs. The majority of the neurons responded to only one of the drugs (32 units, 43.2%) or responded to substance P and capsaicin in opposite directions (9 units, 12.2%). A substance P antagonist, (D-Pro2, D-Trp7,9)-substance P, blocked the substance P-induced excitatory responses in 5 of 6 neurons tested in the anterior hypothalamic-preoptic area, but not the capsaicin-induced excitatory or inhibitory responses (n = 5). It is unlikely that substance P in the anterior hypothalamic-preoptic area participates in the hypothermic effects of capsaicin, observed after local injection.