RESTRAINT-INDUCED CHANGES IN SERUM LUTEINIZING-HORMONE, PROLACTIN, GROWTH-HORMONE AND CORTICOSTERONE LEVELS IN RATS - EFFECT OF SUPERIOR CERVICAL GANGLIONECTOMY

From about 10 to 36 h after superior cervical ganglionectomy (SCGx), p eripheral sympathetic nerve terminals in the median eminence degenerat e, nerve ending content is released, and a transient period of increas ed postsynaptic activity ensues. After this time, an irreversible, par alytic phase is established in the denervated territory. The present e xperiment was undertaken to examine, at single points during the walle rian degeneration phase (24 h after SCGx) and during the paralytic pha se (10 days after denervation), the participation of peripheral sympat hetic nerves in restraint-stress-induced changes of circulating lutein izing hormone (LH), prolactin (PRL), growth hormone (GH) and corticost erone levels. During the wallerian degeneration phase, serum LH did no t augment after stress, as it did in sham-operated controls. In the pa ralytic phase, the poststress increases in LH attained similar values in sham-operated and SCGx rats. Immobilization stress augmented PRL le vels to a similar extent in sham-operated and SCGx rats either 24 h or 10 days after surgery. During the wallerian degeneration phase, a dec rease in serum GH levels was found in unrestrained rats. Immobilizatio n stress decreased GH levels to 5-12% of unrestrained values in sham-o perated and SCGx rats at both examination time points after surgery. R ats studied 24 h after SCGx exhibited significantly augmented serum co rticosterone levels and failed to Show restraint-stress-induced stimul ation of corticosterone release. In rats subjected to SCGx 10 days ear lier, both basal and poststress levels of corticosterone did not diffe r from sham-operated controls. The results suggest that the activity o f peripheral sympathetic nerve terminals may modulate the acute stress responses of LH and corticosterone, but not those of GH and PRL, in r ats.