DIVERGENCE IN THE EXPRESSION OF MOLECULAR MARKERS OF NEURONAL ACTIVATION IN THE PARVOCELLULAR PARAVENTRICULAR NUCLEUS OF THE HYPOTHALAMUS EVOKED BY ALCOHOL ADMINISTRATION VIA DIFFERENT ROUTES
Km. Ogilvie et al., DIVERGENCE IN THE EXPRESSION OF MOLECULAR MARKERS OF NEURONAL ACTIVATION IN THE PARVOCELLULAR PARAVENTRICULAR NUCLEUS OF THE HYPOTHALAMUS EVOKED BY ALCOHOL ADMINISTRATION VIA DIFFERENT ROUTES, The Journal of neuroscience, 18(11), 1998, pp. 4344-4352
Immediate early gene (IEG) expression has been routinely used by neuro
scientists as an index of neuronal activation. In the case of the hypo
thalamic-pituitary-adrenal axis, induction of c-fos and/or NGFI-B mRNA
s in the parvocellular paraventricular nucleus (pPVN) has been documen
ted after a variety of stimuli that increase adrenocorticotropin (ACTH
) in the systemic circulation. However, the functional relationship be
tween expression of IEGs and transcription of the genes for the ACTH s
ecretagogues corticotropin-releasing factor (CRF) and arginine vasopre
ssin (AVP) is not clear. While investigating the neuroendocrine correl
ates of alcohol administration via different routes (intraperitoneal v
s intragastric), we noted a difference in the time course of NGFI-B mR
NA expression in the pPVN, despite comparable dynamics in ACTH secreti
on. By comparing the temporal cascade of transcriptional events in viv
o after alcohol injection via either route, we sought to determine fun
ctional relationships between IEGs and the induction of GRF and AVP he
teronuclear RNAs (hnRNAs). One advantage of our paradigm is the use of
the same stimulus (systemic alcohol injection) in which access to the
CNS does not differ between the groups to be compared. Intraperitonea
l administration of the drug resulted in significant increases in c-fo
s mRNA, Fos protein, CRF hnRNA, and AVP hnRNA. in contrast, intragastr
ic treatment evoked a brief, modest elevation in c-fos mRNA and Fos pr
otein, increased AVP hnRNA, and caused no detectable change in CRF hnR
NA. These data indicate that robust increases in CRF hnRNA are closely
linked to full expression of c-fos mRNA and Fos protein. In addition,
the expression of NGFI-B after both routes of administration is indic
ative of cellular activation within the pPVN in parallel with secretio
n of ACTH.