Search

1 The effect of intracerebroventricular (i.c.v.) injection of histamine on the rectal temperature of Mastomys natalensis at ambient temperatures of 10, 24 and 33 degrees C has been studied. 2 Low doses (0.1-1.0 microgram) of histamine produced hypothermia while larger doses (5-20 micrograms) produced dose-dependent hyperthermia. The hypothermic effect was significantly antagonized by mepyramine while the hyperthermia was blocked by cimetidine. 3 Histamine H1-receptor agonists, 2-methyl-histamine and 2-pyridyl-ethylamine, also produced hypothermia which could be blocked by mepyramine. 4 Histamine H2-receptor agonists, impromidine and dimaprit, produced hyperthermia which was antagonized by cimetidine. 5 Pretreatment of the animals with a beta-adrenoceptor antagonist, MJ1999, did not affect the response to histamine. 6 The hyperthermic effect of histamine (10 micrograms) was most marked at 10 degrees C and was attenuated at 33 degrees C. 7 It is concluded that both H1 and H2-histamine receptors are present in the brain of Mastomys. The H1-receptors mediate hypothermia and H2-receptors hyperthermia.

1. The effect of clonidine on the direct excitability of hypothalamic, medullary and spinal vasomotor loci has been investigated in cats anaesthetized with chloralose. 2. Clonidine inhibited the excitability of these loci when it was localized to the central sites by intracerebroventricular, intravertebral arterial or intrathecal injection in very low doses (1-2 mug). 3. Topical application of clonidine (0.01 percent and 1.0 percent) to the floor of the fourth ventricle inhibited pressor responses evoked either by stimulation of medullary or hypothalamic vasomotor areas. Inhibition of the pressor responses was accompanied by hypotension and bradycardia in many experiments. 4. It appears that effects of clonidine on the vasomotor loci of the medulla oblongata and the spinal cord contribute to its hypotensive action.

1. The effects of intracerebroventricular or intrathecal administration of glycine on some somatic reflexes in chloralosed cats were investigated.2. Glycine produced marked inhibition of the flexor reflex (FR) and crossed extensor reflex (CER) at low doses (2.5-5.0 mg) but even large doses (up to 40.0 mg) had no effect on the facilitation or inhibition of the patellar reflex produced by stimulation of either the reticular formation or the sciatic nerve. The linguomandibular reflex (LMR) could be blocked by 10-20 mg glycine.3. Glycine antagonized strychnine-induced facilitation of FR, CER and LMR and was 5-6 times as active as gamma-aminobutyric acid in this respect.4. The possibility of glycine being a transmitter in spinal pathways is discussed.

1. Anti-inflammatory, analgesic, antipyretic and other pharmacological activities of a new chroman derivative, Centchroman, have been described.2. Centchroman was found to possess significant anti-inflammatory action in the carrageenin-induced oedema test in mice and rats. It inhibited granuloma formation in the cotton pellet test. The anti-arthritic activity was also evident in formaldehyde-induced arthritis and adjuvant-induced arthritis in rats.3. Centchroman had a lower ulcerogenic index than phenylbutazone.4. The mechanism of the anti-inflammatory action of Centchroman seemed to be independent of endogenous adrenocortical hormones or of its weak oestrogenic activity.5. Centchroman antagonized phenylquinone writhing and bradykinin-induced bronchospasm but was devoid of any antipyretic activity.