Center of Experimental Morphology

Departamento de Anatomia - Faculdade de Medicina da Universidade do Porto

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Timed hypocaloric food restriction alters the synthesis and expression of vasopressinnext term and vasoactive intestinal peptide in the suprachiasmatic nucleus


Research Area: Uncategorized Year: 2004
Type of Publication: Article Keywords: Suprachiasmatic nucleus, Food restriction, AVP, VIP, Stereology, Immunocytochemistry, In situ hybridization
Authors:
Journal: Brain Research Volume: 1022
Number: 1-2
Month: October
BibTex:
Abstract:
In mammals, the main circadian pacemaker is located in the suprachiasmatic nucleus (SCN) and its most potent synchronizer is the daily variation of the intensity of light. However, other nonphotic cues, such as previous termtimed food restriction,next term can induce changes in the circadian rhythms, leading also to the appearance of a previous termfoodnext term-entrained oscillator. The present study was designed to establish if the alterations of the circadian rhythms induced by previous termtimed hypocaloric food restrictionnext term are accompanied by structural changes in the SCN. Two groups of adult rats, both maintained on 12-h light/12-h dark cycles, were used; in one group, animals had permanent free access to previous termfood,next term whereas in the other they were subjected to a restricted previous termhypocaloricnext term early morning feeding during 7 months. Using stereological techniques and in situ hybridization, we have examined the structure of the SCN and the previous termsynthesis and expression of vasopressinnext term (AVP) and vasoactive intestinal peptide (VIP). The volume of the SCN and the total number of neurons did not vary between the two groups. However, the total number of AVP- and VIP-immunoreactive neurons and the AVP and VIP mRNA levels were significantly decreased in previous termtimed hypocaloric foodnext term-restricted animals. The results indicate that previous termtimed hypocaloric food restrictionnext term has led to changes of AVP and VIP content of the neurons. They furthermore suggest the existence of a coupling between the previous termfoodnext term-entrainable oscillator and the light-entrainable pacemaker.

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