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Biomedical subjects

M T Lin

Publications and source records attributed to M T Lin.

At least 307 records · Page 17Linked to original sources
PubMed1981

Activation of striatal dopamine receptors induces pain inhibition in rats.

In the rat, elevating dopamine content in corpus striatum with electrical stimulation of substantia nigra or direct administration of apomorphine (50-200 micrograms) into the lateral cerebral ventricle or apomorphine (2-10 microgram) into the caudate-putamen complex decreased pain sensitivity (as shown by an increase in the latency to hind-paw lick in the hot plate test). Furthermore, the decreased pain sensitivity after the central administration of apomorphine was antagonized by pretreatment with haloperidol (a dopamine antagonist). On the other hand, lowering dopamine content in corpus striatum with electrolytic destruction of substantia nigra and 6-hydroxydopamine lesions to the substantia nigra, as well as direct injection of haloperidol into the lateral cerebral ventricle or caudate-putamen complex increased pain sensitivity. The data indicate that activation of striatal dopamine receptors in rat brain induces pain inhibition.

Animals↗
PubMed1981

Effects of adenosine 3',5'-cyclic monophosphate on thermoregulation in both rats and rabbits.

The effects of intraventricular administration of dibutyryl adenosine 3',5'-cyclic monophosphate (db cyclic AMP) on the thermoregulatory responses of unanesthetized rats and rabbits to different ambient temperatures (Ta) were assessed. Administration of db cyclic AMP (10-60 mM) produced dose-dependent hypothermia in both rats and rabbits at Ta 2-22 degrees C. The hypothermia in response to db cyclic AMP was due to decreased metabolic heat production and cutaneous vasodilatation. There was no change in respiratory evaporative heat loss. In contrast, in the heat (30-32 degrees C), db cyclic AMP administration produced dose-dependent hyperthermia in these animals. The hyperthermia was due to increased metabolism (due to muscular shivering) and decreased heat losses. The reduction in heat losses was shown by a decrease in both cutaneous circulation and respiratory evaporative heat loss. The data demonstrate that the thermoregulatory responses induced by central administration of db cyclic AMP are Ta-dependent.

Animals↗
PubMed1981

In vivo and in vitro studies on the mechanism of cardiovascular effects of Wu-Chu-Yu (Evodiae fructus).

The effects of the Chinese herb Wu-Chu-Yu (Evodiae fructus) on the cardiovascular function were assessed in anesthetized cats, conscious rats, and isolated preparations of rat aortic strip and auricle. In anesthetized cats, intravenous administration of alcohol-water crude extracts of Wu-Chu-Yu (0.03-0.24 g/kg) produced a dose-dependent hypertension and an increased contractile force of nictitating membrane which lasted for more than 5 min in higher doses. Phentolamine, but not tetraethylammonium antagonized hypertension and the increased contractile force of nictitating membrane induced by Wu-Chu-Yu. In conscious rats, hypertension was also observed by intraperitoneal administration of Wu-Chu-Yu (6 g/kg). Bilateral nephrectomy, administration of phentolamine or propranolol, all significantly decreased the hypertensive effect of Wu-Chu-Yu. Pretreatment with reserpine 24 hours in advance did not change the pressor effect of the crude extract. In aortic strip preparations, Wu-Chu-Yu caused the increase of contractile force, and the dose-response curve was parallel shift to the right in the presence of phentolamine. In auricle preparations, Wu-Chu-Yu produced positive inotropic and positive chronotropic effects, and the presence of propranolol changed the slope of Wu-Chu-Yu's dose-inotropic effect curve and reversed the chronotropic effect from positive to negative. Both in vivo and in vitro results suggested that alpha and beta adrenoceptors were directly involved in the cardiovascular effects of Wu-Chu-Yu.

Animals↗
PubMed1981

Needle stimulation of acupuncture loci Chu-Chih (LI-11) and Ho-Ku (LI-4) induces hypothermia effects and analgesia in normal adults.

The effects of acupuncture stimulation on the Chu-Chih (LI-11) and Ho-Ku (LI-4) loci on both thermoregulatory function and analgesic activity were assessed in normal adults. Stimulation of Chu-Chih and Ho-Ku each produced both hypothermia and analgesia. The hypothermia was brought about by decreased metabolic heat production and cutaneous vasodilatation (as estimated by an increase in cutaneous temperature). The analgesic effect was shown by an increase in the latency to palm lift in the hot plate test. Thus, the data indicate that stimulation of acupuncture loci Chu-Chih and Ho-Ku is an ideal treatment for both the fever and painful syndromes.

Acupuncture Therapy↗
PubMed1981

Serotoninergic mechanisms of the hypothermia induced by clerodenron fragrans (Ventenaceae) in the rat.

The effects of the Chinese herb Chou-Mou-Li, clerodenron fragrans (Ventenaceae) on metabolic, respiratory and vasomotor activities as well as body temperature were assessed in conscious rats at three different ambient temperatures (Ta) of 8, 22 and 30 degrees C. Intraperitoneal administration of Chou-Mou-li produced dose-dependent hypothermia in rats at both 8 and 22 degrees C Ta- At 8 degrees C Ta the hypothermia in response to Chou-Mou-Li was due to decreased metabolism, while at 22 degrees C Ta the hypothermia was due to both decreased metabolism and cutaneous vasodilatation. There was no change in respiratory evaporative heat loss. Furthermore, the hypothermia induced by Chou-Mou-Li was greatly antagonized by pretreatment of animals with p-chlorophenylalanine (a selective depletor of brain serotonin), but not by either atropine sulfate (a selective blocker of cholinergic receptors), regitine (a selective blocker of alpha-adrenergic receptors) or DL-propranolol (a selective blocker of beta-adrenergic receptors). However, at 30 degrees C Ta, systemic administration of Chou-Mou-Li produced no change in rectal temperature or other thermoregulatory responses. On the other hand, direct administration of serotonin into the lateral cerebral ventricle of conscious rats also produced dose-dependent hypothermia at 8 and 22 degrees C Ta. Again, the hypothermia in response to serotonin was due to decreased metabolism at 8 degrees C Ta and was due to both decreased metabolism and cutaneous vasodilatation at 22 degrees C Ta. At 30 degrees C Ta administration of serotonin also produced no change in thermoregulatory functions. The data indicate that Chou-Mou-Li produces hypothermia by increasing sensible heat loss and decreasing metabolic heat production, probably via the release of endogenous serotonin within brain.

Animals↗
PubMed1981

Effects of needle stimulation of acupuncture loci Nei-Kuan (EH-6), Tsu-San-Li (St-36), San-Yin-Chiao (Sp-6) and Chu-Chih (LI-11) on cutaneous temperature and pain threshold in normal adults.

The effects of stimulation of acupuncture loci Nei-Kuan (EH-6), Tsu-San-Li (St-36), San-Yin-Chiao (Sp-6) and Chu-Chih (LI-11) on cutaneous circulation and/or pain threshold were assessed in eight normal adults. Stimulation of acupuncture locus San-Yin-Chiao (located in the right leg) produced vasoconstriction in the right leg skin temperature (Tright leg) and in the left leg skin temperature (Tleft leg). There was no change in either right arm skin temperature (Tright arm), left arm skin temperature (Tleft arm), metabolic rate, or respiratory evaporative heat loss. Stimulation of Nei-Kuan (located in the right arm) produced vasoconstriction only in both Tright arm and Tleft arm without changes in Tright leg or Tleft leg. Stimulation of acupuncture locus Tsu-San-Li (located in the left leg) produced vasoconstriction in both Tleft leg and Tright leg without changes in either Tright arm or Tleft arm. Stimulation of acupuncture locus Chu-Chih (located in the left arm) produced vasodilatation in both Tleft arm and Tright arm without changes in either Tright leg or Tleft leg. On the other hand, stimulation of acupuncture locus San-Yin-Chiao (right side) produced analgesia only in the right foot sole, while stimulation of acupuncture locus Chu-Chih (left side) produced analgesia only in the left hand palm. Thus, the data indicate that each acupuncture locus may have its own topographical representation with special reference to both cutaneous circulation and pain threshold in normal adults.

Acupuncture Therapy↗
PubMed1981

Effects of intraventricular administration of sympathomimetic agents on metabolic, vasomotor and temperature responses in Taiwan monkeys.

Intraventricular administration of either norepinephrine, tyramine or angiotensin II produced dose-dependent hypothermia, decreased metabolism and lowered cutaneous temperatures in Taiwan monkeys at ambient temperatures of 4 and 22 degrees C. The hypothermia reflected the heat storage consequent to the net effects of decreased heat production and decreased heat loss. In heat (35 degrees C), these agents produced dose-dependent hyperthermia in monkeys. The hyperthermia was brought about mainly by a decrease in dry heat loss.

Angiotensin II↗
PubMed1980

Effects of thyrotrophic-releasing hormone (TRH) on thermoregulation in the rat.

At ambient temperatures (Ta) of both 8 and 22 degrees C, intraventricular administration of TRH (10-80 microgram) produced a dose-dependent hypothermia in rats. The hypothermia was due to both decreased metabolic heat production and cutaneous vasodilatation. In contrast, at 30 degrees C Ta, TRH increased metabolic heat production (due to behavioral excitation) and led to hyperthermia.

Animals↗
PubMed1980

Intraventricular administration of isoproterenol inhibits both heat production and heat loss mechanisms in rats.

At an ambient temperature (Ta) of 8 degrees C, intraventricular administration of isoproterenol inhibited metabolic heat production and led to hypothermia in rats. In contrast, at a Ta of 22 degrees C and of 30 degrees C, isoproterenol decreased cutaneous circulation and led to hyperthermia. The data indicate that isoproterenol inhibits both heat production and heat loss mechanisms in rats.

Animals↗
PubMed1980

Effects of angiotensin II on metabolic, respiratory and vasomotor activities as well as body temperatures in the rabbit.

The effects of intraventricular administration of angiotensin II (10 to 50 micrograms, third cerebral ventricle) on thermoregulatory responses of conscious rabbits to different ambient temperatures (Ta) of 2, 22 and 32 degrees C were assessed. Angiotensin II administration produced dose-dependent hypothermia in rabbits at both 2 and 22 degrees C Ta. The hypothermia in response to angiotensin II was due to decreased metabolic heat production and increased heat losses. The increase in heat loss was shown by an increase in both skin blood flow and respiratory evaporative heat loss. However, at 32 degrees C Ta, angiotensin II produced no change in rectal temperature or other thermoregulatory responses. The data indicate that angiotensin II decreases heat production and increases heat loss mechanisms in the rabbit brain which leads to hypothermia.

Angiotensin II↗