Seasonal variations of Substance P in the striatum of the female rat are affected by maternal and offspring pinealectomy

The effect of pinealectomy (PIN-X) and PIN-X + melatonin treatment during pregnancy (PIN-X + MEL) 100 μg/100 g body weight on Substance P (SP) in the striatum was investigated in offspring female rats. Female offspring were divided into control and PIN-X at the neonatal period, and studied at days 31 and 60. PIN-X mother/control offspring showed a positive influence on striatal SP values in winter, at both ages and in spring at day 31. However, this effect of maternal PIN-X was not observed in summer or fall. The effect of PIN-X on the offspring showed a positive effect in spring at day 31 and summer at the two ages studied. This effect was not observed in fall or winter. Two generations, PIN-X mother/PIN-X offspring, altered the effect of mother or offspring PIN-X and decreased the SP values in winter, spring and summer. Only striatal SP at day 60 in fall was increased. In two generations PIN-X, the striatal SP values were similar to those observed in control mother/control offspring. The effect of PIN-X + MEL treatment on mothers during pregnancy was inhibitory for the intact offspring and stimulatory for PIN-X offspring. In conclusion, the results indicate that maternal and offspring PIN-X seem to exert a rotative and positive seasonal influence from winter to spring to summer. Two generations PIN-X disrupted this rotative circuit and in fall a compensatory discharge of SP was observed.

Research highlights
► We investigated the influence of maternal pineal gland on SP seasonal variations.
► Maternal pinealectomy altered the offspring SP in winter and spring.
► Offspring pinealectomy altered the offspring SP in spring and summer.
► Two generations pinealectomy disrupted the SP seasonal circuit and in fall.