Plasma Cortisol of Conscious Cats during Cerebroventricular Perfusion with Adrenergic, Cholinergic and Gabanergic Antagonists

Abstract

Adrenergic (α and β), cholinergic (m and n) and gabanergic (γ) influences on the regulation of basal hypothalamo-hypophyseal-adrenocortical (HHA) activity, as assessed by plasma cortisol levels, were investigated in non-stressed conscious cats. Alterations in neurotransmitter activities were induced by perfusing the cerebroventricles for 60 min with mock cerebrospinal fluid containing α, β, m, n and γ antagonists given alone or in various combinations. Neither γ, m nor n blockers altered basal HHA activity, whereas both α and β blockers given alone or together, or combined with m, n and γ blockers markedly elevated plasma cortisol. These responses were inhibited by the addition of dexamethasone to the perfusion fluid. These data suggest that basal HHA activity in the cat is maintained by a central inhibitory action of the adrenergic system on spontaneously discharging corticotropin-releasing factor neurons, and not via an adrenergic-cholinergic-gabanergic neural chain.

Clinical Studies of the Cholinergic Deficit in Alzheimer's Disease

“…A pronounced degeneration of the locus coeruleus occurs in some patients with AD/SDAT 18,38–40 . A change in the noradrenergic cells of origin could have neuroendocrine consequences 41–45 . The tendency toward increased plasma cortisol with decreased CSF MHPG may reflect locus coeruleus degeneration in certain patients.…”