Circadian Organization of the Immune Response: Rat Adjuvant Arthritis as a Model - New Insights to Neuroimmune Biology - page 120

(TSH) release, and further found that this effect was partially sensitive to immunosup-
pression by cyclosporine [65] ( Tables 6.2 and 6.3 ). Further experiments indicated that
hypothalamic levels of corticotropin-releasing hormone (CRH), thyrotropin-releasing
hormone (TRH), GH-releasing hormone (GHRH), and somatostatin were altered in
the preclinical phase of arthritis [106] . In the median eminence, rats injected with
the adjuvant vehicle exhibited significant 24-hour variations for the four hypophys-
iotropic hormones examined, with maxima at noon. These 24-hour rhythms were
inhibited or suppressed 3 days after FCA injection. Administration of the immuno-
suppressant drug cyclosporine impaired the depressing effect of FCA injection on
CRH, TRH, and somatostatin content in median eminence, but not on GHRH. The
activity of cyclosporine was less evident in other hypothalamic regions examined
[106] . Generally, a decrease in amplitude or mesor of transmitter rhythms was detect-
able, mainly in anterior and medial hypothalamic regions [107] ( Table 6.2 ).

Table 6.2 Summary of Changes in Circadian Rhythms of Hypothalamic and Hypophysial
Hormones and Neurotransmitters, Pineal Melatonin, and Plasma Proteins during the
Preclinical (3rd day) Phases of Freund's Adjuvant Arthritis in Rats

24-Hour Rhythms Amplitude Acrophase Mean

Preclinical Phase
Serum
ACTH Unchanged Unchanged Augmented

Prolactin Unchanged Unchanged Augmented

GH Absence of rhythm Absence of rhythm Decreased

TSH Suppression of rhythm Suppression of rhythm Decreased

LH Suppression of rhythm Suppression of rhythm Decreased

Albumin Absence of rhythm Absence of rhythm Unchanged

-1 globulin Decreased Unchanged Unchanged

-2 globulin Decreased Unchanged Decreased

-globulin Absence of rhythm Absence of rhythm Unchanged

-globulin Absence of rhythm Absence of rhythm Unchanged

Median eminence
CRH Decreased Unchanged Decreased

TRH Suppression of rhythm Suppression of rhythm Decreased

GHRH Decreased Unchanged Decreased

Somatostatin Decreased Unchanged Decreased

NE Decreased Unchanged Unchanged

DA turnover Unchanged Changed Unchanged

5-HT turnover Suppression of rhythm Suppression of rhythm Decreased

( Continued )