[The role on non-adrenergic regulation in the reaction of the rat pineal body to acute hypoxia and epithalamine administration].

The influence of co-administration of alpha-methyl-p-tyrosine (inhibitor of catecholamine synthesis) and alpha-(+) beta-adrenergic antagonists under conditions of acute hypobaric hypoxia or pretreatment with epithalamin on cyclic nucleotide content in the pineal gland of juvenile male albino rats was investigated. Acute hypoxia was accompanied by increase of pineal level of cyclic nucleotides and administration of adrenoreceptor antagonists attenuated this effect. Pretreatment of animals with adrenoreceptor antagonists did not influence the effect of acute hypobaric hypoxia on pineal cyclic nucleotide content. This suggests involvement of non-adrenergic mechanisms into augmentation of pineal cyclic nucleotide level. Administration of epithalamin caused an increase of pineal cGMP. Administration of epithalamin to rats pretreated with adrenoreceptor antagonists increased pineal cGMP and to a lesser extent cAMP content. The latter suggests that epithalamin effect was not mediated via sympathetic innervation. It is concluded that non-adrenergic innervation and humoral regulatory mechanisms are obviously involved into activation of pineal gland under conditions of acute stress.