Neurotransmitter regulation of somatostatin secretion by fetal rat cerebral cortical cells in culture

Abstract

Extensive studies exploring the regulation of hypothalamic somatostatin GHRIH release have been reported, but the factors regulating GHRIH release in the cerebral cortex have not been well defined. We have studied the effects of central neurotransmitters on GHRIH secretion by cultured fetal rat cerebral cortical cells and on intracellular GHRIH levels. Cells maintained in vitro for 15-20 days were incubated with dopamine (DA), acetylcholine (ACh), gamma-aminobutyric acid (GABA), norepinephrine (NE), serotonin (SE) or histamine (His) (10(-11) M to 10(3) M) for 30 minutes. Following incubation, immunoreactive GHRIH was measured by RIA in cell extracts and incubation media. DA increased intracellular GHRIH content but have no effect on GHRIH in the media. Both media and intracellular GHRIH content were significantly reduced by GABA and SE. The effect of NE was stimulatory at low (10(-9) M) and inhibitory at high (10(-5) M to 10(-3) M) concentrations. ACh was found to increase media GHRIH and to decrease intracellular GHRIH content; 30 min exposure to His did not significantly modify either media or intracellular GHRH. Our findings with fetal rat cerebral cortical cells in culture demonstrate that endogenous neurotransmitters do have the capacity to directly influence GHRIH regulation.

Histamine H1-Receptors Modulate Somatostatin Receptors Coupled to the Inhibition of Adenylyl Cyclase in the Rat Frontoparietal Cortex

“…These results are in good agreement with a study of De los Frailes et al (20) who observed that histamine caused no significant differences in either SS release or SS intracellular content in rat fetal cerebral cortical cells in culture.…”

Dopamine enhances somatostatin receptor-mediated inhibition of adenylate cyclase in rat striatum and hippocampus

“…Other authors have found DA to increase intracellular SS content without affecting SS release (de los Frailes et al, 1993). Previous evidence indicates that DA stimu- Fig.…”

α-Fluoromethylhistidine influences somatostatin content, binding and inhibition of adenylyl cyclase activity in the rat frontoparietal cortex

“…The inhibition of histamine synthesis induced by a-FMH was accompanied by a rise in SSLI content at 6 h after a-FMH administration, although to date, the mechanism is unknown. The studies of the effect of histamine on SS release or SS intracellular content are not clear [49,50]. In some studies, histamine seems to act as a mild inhibitor of SS release in fetal cultured cerebral cortical cells from rat brain, although this effect is not significant at concentrations of up to 10 -5 M [49,50].…”

“…The studies of the effect of histamine on SS release or SS intracellular content are not clear [49,50]. In some studies, histamine seems to act as a mild inhibitor of SS release in fetal cultured cerebral cortical cells from rat brain, although this effect is not significant at concentrations of up to 10 -5 M [49,50]. In the present study, no change in SSLI content was detected at either 1 or 4 h, which suggests that a certain time is required for the effect on SSLI content to take place.…”