Time-dependent GABA-ergic activity in olfactory bulb and hypothalamus of proestrous rats.

Exposure of proestrous rats in the afternoon (1700h) or night (0100h) to intact and castrated male pheromones induced changes in olfactory bulbs and hypothalamic glutamic acid decarboxylase activity. Compared to the values found in control rats, the enzyme activity in the main olfactory bulb measured in the afternoon did not discriminate between the odor of intact or castrated males in the first hour of exposure, whereas in the accessory olfactory bulb, the enzyme activity was increased specifically by castrated male odor. At night, main bulb-enzyme activity was reduced by the intact male pheromone 1 h later, whereas accessory bulb-enzyme activity was increased by castrated male odor.

Glutamic acid decarboxylase in rat olfactory bulb: effect of ovarian steroids or male pheromones.

The effect of ovarian steroids and pheromones on the activity of glutamic acid decarboxylase, the enzyme that synthesizes gamma-aminobutyric acid (GABA), was studied in the rat olfactory bulbs. The enzyme activity was measured in the main and accessory olfactory bulbs at 11:00 h and 17:00 h in ovariectomized rats, and in rats treated with ovarian steroids or exposed to male pheromones. The enzyme activity in both bulbs showed a diurnal fluctuation that was not affected in the accessory bulbs by the exposure to pheromones while the rhythm disappeared in the main bulbs.

Glutamic acid decarboxylase activity of the olfactory bulb in male rats is influenced by olfactory stimuli and hormonal status.

Changes is glutamate decarboxylase activity (GAD) in the main (MOB) and accessory (AOB) olfactory bulbs were determined at 11:00 hr and 17:00 hr in intact odor deprived (IOD) male rats exposed to female olfactory stimuli, and in castrated odor deprived males (COD) either injected with testosterone (T), exposed to female pheromone or injected with T and exposed to pheromone. Grouping IOD males by female olfactory stimulus and time of the day. MOB and AOB-GAD activity changed in the morning and not in the afternoon.

A cyclic AMP mechanism mediates the serotonin-induced increase in glutamic acid decarboxylase activity in the preoptic area and hypothalamus.

Previous studies have shown that the injection of 5-hydroxytryptamine (5-HT) into the third ventricle of rats on the afternoon of proestrus increases glutamic acid decarboxylase (GAD) activity in the preoptic area and the hypothalamus. In the present report we examine the adenylate cyclase-cyclic AMP (cAMP) system as mediator of that effect. The increase in GAD activity induced by intraventricular injection of 5-HT was completely blocked by injecting an antiserum against cAMP into the third ventricle 30 min earlier, whereas an injection of serum from normal rabbits was ineffective.

gamma-Aminobutyric acid activity in the olfactory bulb of the rat during the sexual cycle and response to olfactory stimuli.

Glutamic acid decarboxylase activity in the main and accessory olfactory bulbs throughout the sexual cycle of the rat was studied. The effect of male pheromonal secretion on enzyme activity during proestrus and estrus day was also tested. The enzyme activity showed circadian rhythm during the estrous cycle.