RELEASE OF NEUROTRANSMITTERS AND NEUROSECRETORY SUBSTANCES DURING INVITRO MATURATION OF MOUSE HYPOTHALAMIC CULTURES

The maturation of the neurosecretory activity of a hypothalamic nerve cell population grown in vitro, prepared from 10-day-old mice and cult ured for 6 days, has been demonstrated in the present report. A low-mo lecular weight polypeptide of 30-kD was found to be released into the culture media during the 6-day period of incubation, as analyzed by SD S-polyacrylamide gel electrophoresis. Comparative electrophoresis of t he in situ hypothalamic, neurohypophysis and cerebral cortex homogenat es revealed the presence of a 30-kD protein component in both the hypo thalamus and neurohypophysis but not in the cerebral cortex. The relea se of the 30-kD polypeptide into the incubation media indicates an exp ression of the neurosecretory activity of the peptidergic neurons of t he hypothalamus during in vitro maturation. On the other hand, high pr essure liquid chromatography with electrochemical detection showed app reciable quantities of released dopamine (DA), epinephrine and seroton in (5-HT) in the incubation media in which the neurons were allowed to differentiate. There was a steady release of DA during the 6-day incu bation period, varying from 0.21 +/- 0.02 to 0.49 +/- 0.05 ng/mg prote in. The epinephrine level increased progressively from day 1 to 6 of c ulture, from 3.73 +/- 0.57 to 12.08 +/- 1.81 ng/mg protein, respective ly. The measured 5-HT level was 0.07 +/- 0.001 on day 2 and increased to 0.38 +/- 0.05 ng/mg protein on day 6 of culture. These data demonst rate the functional maturation of catecholaminergic, serotoninergic an d peptidergic neurons in these rotary histotypic cultures of the mouse hypothalamus.