Motor nerve conduction velocity & Hoffman's reflex latency in newborns.

A total of 72 newborns and their mothers were studied to assess the influence of various variables on the motor nerve conduction velocity (MNCV) and Hoffman's reflex latency (H-RL) of the babies with a view to differentiate fullterm and preterm low birth weight babies. MNCV were significantly lower and H-RL significantly higher in preterm appropriate for gestational (PT-AGA) age babies compared to fullterm appropriate for gestational age (FT-AGA) and fullterm intrauterine growth retarded babies (FT-IUGR). In FT-IUGR babies, only MNCV was significantly reduced as compared to FT-AGA babies.

Electrophysiological studies (MNCV, H-RL) in full-term newborn babies.

Twenty-five full-term newborns and their mothers constituted study subjects. Mothers were subjected to weight and height measurements, as well as, serum albumin and hemoglobin estimations. Offsprings were subjected to measurements of weight, crown heel length and head circumference along with motor nerve conduction velocity (MNCV) and H-reflex latency (H-RL). The MNCV was found to be significantly lower in growth retarded (FT-IUGR) babies compared to appropriately grown babies (FT-AGA) whereas H-RL was similar in both FT-IUGR and FT-AGA babies.

Morphine hyperthermia in rats: role of neurochemical substances in brain.

Central neurochemical mechanism underlying the hyperthermic effect of morphine has been investigated in rats. 200 micrograms morphine hydrochloride, when administered through cerebroventricular route at different seasonal air temperature, caused a rise in rectal temperature of rats. This hyperthermia was not affected by prior administration of antiserotonergic (pCPA, 5.6-DHT) or anticatecholaminergic (PBZ, 6-OHDA) drugs, as well as by PGE synthetase inhibitor, indomethacin. Similarity, cholinergic muscarinic or nicotinic receptor blockers, such as atropine and pentolinium/ D-tubocurarine respectively, were ineffective to modify it. Whereas, the depletion of acetylcholine in brain by pretreating the animals with hemicholinium profoundly delayed the hyperthermia, suggesting a central cholinergic involvement in morphine induced hyperthermia in rats.

Studies on rectal temperature of rats in relation to seasonal air temperature and morphine administration.

The present findings demonstrate that seasonal air temperature does not only influence the basal core temperature of rats, but also modifies the physiological/pharmacological actions of drugs. Thus, at low ambient temperature, intracerebroventricular on intraperitoneal administration of morphine produces mainly hypothermia followed by a secondary rise in rectal temperature. On the other hand, at high ambient temperature, the drug produces hyperthermia only. The hypothermic response at low ambient temperature is abolished by pretreatment of rats with 6-hydroxydopamine but not with phenoxybenzamine administration. This suggests that catecholamine pathway in the central nervous system is involved in morphine induced hypothermic response. Further, the role of cholinergic neurons in such response is also indicated.